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git://git.kernel.org/pub/scm/linux/kernel/git/crng/random
Pull random number generator updates from Jason Donenfeld:
"This adds getrandom() support to the vDSO.
First, it adds a new kind of mapping to mmap(2), MAP_DROPPABLE, which
lets the kernel zero out pages anytime under memory pressure, which
enables allocating memory that never gets swapped to disk but also
doesn't count as being mlocked.
Then, the vDSO implementation of getrandom() is introduced in a
generic manner and hooked into random.c.
Next, this is implemented on x86. (Also, though it's not ready for
this pull, somebody has begun an arm64 implementation already)
Finally, two vDSO selftests are added.
There are also two housekeeping cleanup commits"
* tag 'random-6.11-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
MAINTAINERS: add random.h headers to RNG subsection
random: note that RNDGETPOOL was removed in 2.6.9-rc2
selftests/vDSO: add tests for vgetrandom
x86: vdso: Wire up getrandom() vDSO implementation
random: introduce generic vDSO getrandom() implementation
mm: add MAP_DROPPABLE for designating always lazily freeable mappings
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- In the series "mm: Avoid possible overflows in dirty throttling" Jan
Kara addresses a couple of issues in the writeback throttling code.
These fixes are also targetted at -stable kernels.
- Ryusuke Konishi's series "nilfs2: fix potential issues related to
reserved inodes" does that. This should actually be in the
mm-nonmm-stable tree, along with the many other nilfs2 patches. My
bad.
- More folio conversions from Kefeng Wang in the series "mm: convert to
folio_alloc_mpol()"
- Kemeng Shi has sent some cleanups to the writeback code in the series
"Add helper functions to remove repeated code and improve readability
of cgroup writeback"
- Kairui Song has made the swap code a little smaller and a little
faster in the series "mm/swap: clean up and optimize swap cache
index".
- In the series "mm/memory: cleanly support zeropage in
vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David
Hildenbrand has reworked the rather sketchy handling of the use of
the zeropage in MAP_SHARED mappings. I don't see any runtime effects
here - more a cleanup/understandability/maintainablity thing.
- Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling
of higher addresses, for aarch64. The (poorly named) series is
"Restructure va_high_addr_switch".
- The core TLB handling code gets some cleanups and possible slight
optimizations in Bang Li's series "Add update_mmu_tlb_range() to
simplify code".
- Jane Chu has improved the handling of our
fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in
the series "Enhance soft hwpoison handling and injection".
- Jeff Johnson has sent a billion patches everywhere to add
MODULE_DESCRIPTION() to everything. Some landed in this pull.
- In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang
has simplified migration's use of hardware-offload memory copying.
- Yosry Ahmed performs more folio API conversions in his series "mm:
zswap: trivial folio conversions".
- In the series "large folios swap-in: handle refault cases first",
Chuanhua Han inches us forward in the handling of large pages in the
swap code. This is a cleanup and optimization, working toward the end
objective of full support of large folio swapin/out.
- In the series "mm,swap: cleanup VMA based swap readahead window
calculation", Huang Ying has contributed some cleanups and a possible
fixlet to his VMA based swap readahead code.
- In the series "add mTHP support for anonymous shmem" Baolin Wang has
taught anonymous shmem mappings to use multisize THP. By default this
is a no-op - users must opt in vis sysfs controls. Dramatic
improvements in pagefault latency are realized.
- David Hildenbrand has some cleanups to our remaining use of
page_mapcount() in the series "fs/proc: move page_mapcount() to
fs/proc/internal.h".
- David also has some highmem accounting cleanups in the series
"mm/highmem: don't track highmem pages manually".
- Build-time fixes and cleanups from John Hubbard in the series
"cleanups, fixes, and progress towards avoiding "make headers"".
- Cleanups and consolidation of the core pagemap handling from Barry
Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers
and utilize them".
- Lance Yang's series "Reclaim lazyfree THP without splitting" has
reduced the latency of the reclaim of pmd-mapped THPs under fairly
common circumstances. A 10x speedup is seen in a microbenchmark.
It does this by punting to aother CPU but I guess that's a win unless
all CPUs are pegged.
- hugetlb_cgroup cleanups from Xiu Jianfeng in the series
"mm/hugetlb_cgroup: rework on cftypes".
- Miaohe Lin's series "Some cleanups for memory-failure" does just that
thing.
- Someone other than SeongJae has developed a DAMON feature in Honggyu
Kim's series "DAMON based tiered memory management for CXL memory".
This adds DAMON features which may be used to help determine the
efficiency of our placement of CXL/PCIe attached DRAM.
- DAMON user API centralization and simplificatio work in SeongJae
Park's series "mm/damon: introduce DAMON parameters online commit
function".
- In the series "mm: page_type, zsmalloc and page_mapcount_reset()"
David Hildenbrand does some maintenance work on zsmalloc - partially
modernizing its use of pageframe fields.
- Kefeng Wang provides more folio conversions in the series "mm: remove
page_maybe_dma_pinned() and page_mkclean()".
- More cleanup from David Hildenbrand, this time in the series
"mm/memory_hotplug: use PageOffline() instead of PageReserved() for
!ZONE_DEVICE". It "enlightens memory hotplug more about PageOffline()
pages" and permits the removal of some virtio-mem hacks.
- Barry Song's series "mm: clarify folio_add_new_anon_rmap() and
__folio_add_anon_rmap()" is a cleanup to the anon folio handling in
preparation for mTHP (multisize THP) swapin.
- Kefeng Wang's series "mm: improve clear and copy user folio"
implements more folio conversions, this time in the area of large
folio userspace copying.
- The series "Docs/mm/damon/maintaier-profile: document a mailing tool
and community meetup series" tells people how to get better involved
with other DAMON developers. From SeongJae Park.
- A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does
that.
- David Hildenbrand sends along more cleanups, this time against the
migration code. The series is "mm/migrate: move NUMA hinting fault
folio isolation + checks under PTL".
- Jan Kara has found quite a lot of strangenesses and minor errors in
the readahead code. He addresses this in the series "mm: Fix various
readahead quirks".
- SeongJae Park's series "selftests/damon: test DAMOS tried regions and
{min,max}_nr_regions" adds features and addresses errors in DAMON's
self testing code.
- Gavin Shan has found a userspace-triggerable WARN in the pagecache
code. The series "mm/filemap: Limit page cache size to that supported
by xarray" addresses this. The series is marked cc:stable.
- Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations
and cleanup" cleans up and slightly optimizes KSM.
- Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of
code motion. The series (which also makes the memcg-v1 code
Kconfigurable) are "mm: memcg: separate legacy cgroup v1 code and put
under config option" and "mm: memcg: put cgroup v1-specific memcg
data under CONFIG_MEMCG_V1"
- Dan Schatzberg's series "Add swappiness argument to memory.reclaim"
adds an additional feature to this cgroup-v2 control file.
- The series "Userspace controls soft-offline pages" from Jiaqi Yan
permits userspace to stop the kernel's automatic treatment of
excessive correctable memory errors. In order to permit userspace to
monitor and handle this situation.
- Kefeng Wang's series "mm: migrate: support poison recover from
migrate folio" teaches the kernel to appropriately handle migration
from poisoned source folios rather than simply panicing.
- SeongJae Park's series "Docs/damon: minor fixups and improvements"
does those things.
- In the series "mm/zsmalloc: change back to per-size_class lock"
Chengming Zhou improves zsmalloc's scalability and memory
utilization.
- Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for
pinning memfd folios" makes the GUP code use FOLL_PIN rather than
bare refcount increments. So these paes can first be moved aside if
they reside in the movable zone or a CMA block.
- Andrii Nakryiko has added a binary ioctl()-based API to
/proc/pid/maps for much faster reading of vma information. The series
is "query VMAs from /proc/<pid>/maps".
- In the series "mm: introduce per-order mTHP split counters" Lance
Yang improves the kernel's presentation of developer information
related to multisize THP splitting.
- Michael Ellerman has developed the series "Reimplement huge pages
without hugepd on powerpc (8xx, e500, book3s/64)". This permits
userspace to use all available huge page sizes.
- In the series "revert unconditional slab and page allocator fault
injection calls" Vlastimil Babka removes a performance-affecting and
not very useful feature from slab fault injection.
* tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (411 commits)
mm/mglru: fix ineffective protection calculation
mm/zswap: fix a white space issue
mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio
mm/hugetlb: fix possible recursive locking detected warning
mm/gup: clear the LRU flag of a page before adding to LRU batch
mm/numa_balancing: teach mpol_to_str about the balancing mode
mm: memcg1: convert charge move flags to unsigned long long
alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting
lib: reuse page_ext_data() to obtain codetag_ref
lib: add missing newline character in the warning message
mm/mglru: fix overshooting shrinker memory
mm/mglru: fix div-by-zero in vmpressure_calc_level()
mm/kmemleak: replace strncpy() with strscpy()
mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB
mm: ignore data-race in __swap_writepage
hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr
mm: shmem: rename mTHP shmem counters
mm: swap_state: use folio_alloc_mpol() in __read_swap_cache_async()
mm/migrate: putback split folios when numa hint migration fails
...
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The vDSO getrandom() implementation works with a buffer allocated with a
new system call that has certain requirements:
- It shouldn't be written to core dumps.
* Easy: VM_DONTDUMP.
- It should be zeroed on fork.
* Easy: VM_WIPEONFORK.
- It shouldn't be written to swap.
* Uh-oh: mlock is rlimited.
* Uh-oh: mlock isn't inherited by forks.
- It shouldn't reserve actual memory, but it also shouldn't crash when
page faulting in memory if none is available
* Uh-oh: VM_NORESERVE means segfaults.
It turns out that the vDSO getrandom() function has three really nice
characteristics that we can exploit to solve this problem:
1) Due to being wiped during fork(), the vDSO code is already robust to
having the contents of the pages it reads zeroed out midway through
the function's execution.
2) In the absolute worst case of whatever contingency we're coding for,
we have the option to fallback to the getrandom() syscall, and
everything is fine.
3) The buffers the function uses are only ever useful for a maximum of
60 seconds -- a sort of cache, rather than a long term allocation.
These characteristics mean that we can introduce VM_DROPPABLE, which
has the following semantics:
a) It never is written out to swap.
b) Under memory pressure, mm can just drop the pages (so that they're
zero when read back again).
c) It is inherited by fork.
d) It doesn't count against the mlock budget, since nothing is locked.
e) If there's not enough memory to service a page fault, it's not fatal,
and no signal is sent.
This way, allocations used by vDSO getrandom() can use:
VM_DROPPABLE | VM_DONTDUMP | VM_WIPEONFORK | VM_NORESERVE
And there will be no problem with OOMing, crashing on overcommitment,
using memory when not in use, not wiping on fork(), coredumps, or
writing out to swap.
In order to let vDSO getrandom() use this, expose these via mmap(2) as
MAP_DROPPABLE.
Note that this involves removing the MADV_FREE special case from
sort_folio(), which according to Yu Zhao is unnecessary and will simply
result in an extra call to shrink_folio_list() in the worst case. The
chunk removed reenables the swapbacked flag, which we don't want for
VM_DROPPABLE, and we can't conditionalize it here because there isn't a
vma reference available.
Finally, the provided self test ensures that this is working as desired.
Cc: linux-mm@kvack.org
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
Pull sysctl updates from Joel Granados:
- Remove "->procname == NULL" check when iterating through sysctl table
arrays
Removing sentinels in ctl_table arrays reduces the build time size
and runtime memory consumed by ~64 bytes per array. With all
ctl_table sentinels gone, the additional check for ->procname == NULL
that worked in tandem with the ARRAY_SIZE to calculate the size of
the ctl_table arrays is no longer needed and has been removed. The
sysctl register functions now returns an error if a sentinel is used.
- Preparation patches for sysctl constification
Constifying ctl_table structs prevents the modification of
proc_handler function pointers as they would reside in .rodata. The
ctl_table arguments in sysctl utility functions are const qualified
in preparation for a future treewide proc_handler argument
constification commit.
- Misc fixes
Increase robustness of set_ownership by providing sane default
ownership values in case the callee doesn't set them. Bound check
proc_dou8vec_minmax to avoid loading buggy modules and give sysctl
testing module a name to avoid compiler complaints.
* tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
sysctl: Warn on an empty procname element
sysctl: Remove ctl_table sentinel code comments
sysctl: Remove "child" sysctl code comments
sysctl: Remove superfluous empty allocations from sysctl internals
sysctl: Replace nr_entries with ctl_table_size in new_links
sysctl: Remove check for sentinel element in ctl_table arrays
mm profiling: Remove superfluous sentinel element from ctl_table
locking: Remove superfluous sentinel element from kern_lockdep_table
sysctl: Add module description to sysctl-testing
sysctl: constify ctl_table arguments of utility function
utsname: constify ctl_table arguments of utility function
sysctl: move the extra1/2 boundary check of u8 to sysctl_check_table_array
sysctl: always initialize i_uid/i_gid
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Support passing NULL along AT_EMPTY_PATH for statx().
NULL paths with any flag value other than AT_EMPTY_PATH go the
usual route and end up with -EFAULT to retain compatibility (Rust
is abusing calls of the sort to detect availability of statx)
This avoids path lookup code, lockref management, memory allocation
and in case of NULL path userspace memory access (which can be
quite expensive with SMAP on x86_64)
- Don't block i_writecount during exec. Remove the
deny_write_access() mechanism for executables
- Relax open_by_handle_at() permissions in specific cases where we
can prove that the caller had sufficient privileges to open a file
- Switch timespec64 fields in struct inode to discrete integers
freeing up 4 bytes
Fixes:
- Fix false positive circular locking warning in hfsplus
- Initialize hfs_inode_info after hfs_alloc_inode() in hfs
- Avoid accidental overflows in vfs_fallocate()
- Don't interrupt fallocate with EINTR in tmpfs to avoid constantly
restarting shmem_fallocate()
- Add missing quote in comment in fs/readdir
Cleanups:
- Don't assign and test in an if statement in mqueue. Move the
assignment out of the if statement
- Reflow the logic in may_create_in_sticky()
- Remove the usage of the deprecated ida_simple_xx() API from procfs
- Reject FSCONFIG_CMD_CREATE_EXCL requets that depend on the new
mount api early
- Rename variables in copy_tree() to make it easier to understand
- Replace WARN(down_read_trylock, ...) abuse with proper asserts in
various places in the VFS
- Get rid of user_path_at_empty() and drop the empty argument from
getname_flags()
- Check for error while copying and no path in one branch in
getname_flags()
- Avoid redundant smp_mb() for THP handling in do_dentry_open()
- Rename parent_ino to d_parent_ino and make it use RCU
- Remove unused header include in fs/readdir
- Export in_group_capable() helper and switch f2fs and fuse over to
it instead of open-coding the logic in both places"
* tag 'vfs-6.11.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits)
ipc: mqueue: remove assignment from IS_ERR argument
vfs: rename parent_ino to d_parent_ino and make it use RCU
vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)
stat: use vfs_empty_path() helper
fs: new helper vfs_empty_path()
fs: reflow may_create_in_sticky()
vfs: remove redundant smp_mb for thp handling in do_dentry_open
fuse: Use in_group_or_capable() helper
f2fs: Use in_group_or_capable() helper
fs: Export in_group_or_capable()
vfs: reorder checks in may_create_in_sticky
hfs: fix to initialize fields of hfs_inode_info after hfs_alloc_inode()
proc: Remove usage of the deprecated ida_simple_xx() API
hfsplus: fix to avoid false alarm of circular locking
Improve readability of copy_tree
vfs: shave a branch in getname_flags
vfs: retire user_path_at_empty and drop empty arg from getname_flags
vfs: stop using user_path_at_empty in do_readlinkat
tmpfs: don't interrupt fallocate with EINTR
fs: don't block i_writecount during exec
...
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When folio is isolated, the PG_lru bit is cleared. So the PG_lru check in
stable_page_flags() will miss this kind of isolated folios. Use
folio_test_large_rmappable() instead to also include isolated folios.
Since pagecache supports large folios and the introduction of mTHP, the
semantics of KPF_THP have been expanded, now it indicates not only
PMD-sized THP. Update related documentation to clearly state that KPF_THP
indicates multiple order THPs.
[ran.xiaokai@zte.com.cn: directly use is_zero_folio(), per David]
Link: https://lkml.kernel.org/r/20240708062601.165215-1-ranxiaokai627@163.com
Link: https://lkml.kernel.org/r/20240705104343.112680-1-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrei Vagin <avagin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Svetly Todorov <svetly.todorov@memverge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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On powerpc 8xx huge_ptep_get() will need to know whether the given ptep is
a PTE entry or a PMD entry. This cannot be known with the PMD entry
itself because there is no easy way to know it from the content of the
entry.
So huge_ptep_get() will need to know either the size of the page or get
the pmd.
In order to be consistent with huge_ptep_get_and_clear(), give mm and
address to huge_ptep_get().
Link: https://lkml.kernel.org/r/cc00c70dd384298796a4e1b25d6c4eb306d3af85.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The need to get ELF build ID reliably is an important aspect when dealing
with profiling and stack trace symbolization, and /proc/<pid>/maps textual
representation doesn't help with this.
To get backing file's ELF build ID, application has to first resolve VMA,
then use it's start/end address range to follow a special
/proc/<pid>/map_files/<start>-<end> symlink to open the ELF file (this is
necessary because backing file might have been removed from the disk or
was already replaced with another binary in the same file path.
Such approach, beyond just adding complexity of having to do a bunch of
extra work, has extra security implications. Because application opens
underlying ELF file and needs read access to its entire contents (as far
as kernel is concerned), kernel puts additional capable() checks on
following /proc/<pid>/map_files/<start>-<end> symlink. And that makes
sense in general.
But in the case of build ID, profiler/symbolizer doesn't need the contents
of ELF file, per se. It's only build ID that is of interest, and ELF
build ID itself doesn't provide any sensitive information.
So this patch adds a way to request backing file's ELF build ID along the
rest of VMA information in the same API. User has control over whether
this piece of information is requested or not by either setting
build_id_size field to zero or non-zero maximum buffer size they provided
through build_id_addr field (which encodes user pointer as __u64 field).
This is a completely optional piece of information, and so has no
performance implications for user cases that don't care about build ID,
while improving performance and simplifying the setup for those
application that do need it.
Kernel already implements build ID fetching, which is used from BPF
subsystem. We are reusing this code here, but plan a follow up changes to
make it work better under more relaxed assumption (compared to what
existing code assumes) of being called from user process context, in which
page faults are allowed. BPF-specific implementation currently bails out
if necessary part of ELF file is not paged in, all due to extra
BPF-specific restrictions (like the need to fetch build ID in restrictive
contexts such as NMI handler).
[andrii@kernel.org: fix integer to pointer cast warning in do_procmap_query()]
Link: https://lkml.kernel.org/r/20240701174805.1897344-1-andrii@kernel.org
Link: https://lkml.kernel.org/r/20240627170900.1672542-4-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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/proc/<pid>/maps file is extremely useful in practice for various tasks
involving figuring out process memory layout, what files are backing any
given memory range, etc. One important class of applications that
absolutely rely on this are profilers/stack symbolizers (perf tool being
one of them). Patterns of use differ, but they generally would fall into
two categories.
In on-demand pattern, a profiler/symbolizer would normally capture stack
trace containing absolute memory addresses of some functions, and would
then use /proc/<pid>/maps file to find corresponding backing ELF files
(normally, only executable VMAs are of interest), file offsets within
them, and then continue from there to get yet more information (ELF
symbols, DWARF information) to get human-readable symbolic information.
This pattern is used by Meta's fleet-wide profiler, as one example.
In preprocessing pattern, application doesn't know the set of addresses of
interest, so it has to fetch all relevant VMAs (again, probably only
executable ones), store or cache them, then proceed with profiling and
stack trace capture. Once done, it would do symbolization based on stored
VMA information. This can happen at much later point in time. This
patterns is used by perf tool, as an example.
In either case, there are both performance and correctness requirement
involved. This address to VMA information translation has to be done as
efficiently as possible, but also not miss any VMA (especially in the case
of loading/unloading shared libraries). In practice, correctness can't be
guaranteed (due to process dying before VMA data can be captured, or
shared library being unloaded, etc), but any effort to maximize the chance
of finding the VMA is appreciated.
Unfortunately, for all the /proc/<pid>/maps file universality and
usefulness, it doesn't fit the above use cases 100%.
First, it's main purpose is to emit all VMAs sequentially, but in practice
captured addresses would fall only into a smaller subset of all process'
VMAs, mainly containing executable text. Yet, library would need to parse
most or all of the contents to find needed VMAs, as there is no way to
skip VMAs that are of no use. Efficient library can do the linear pass
and it is still relatively efficient, but it's definitely an overhead that
can be avoided, if there was a way to do more targeted querying of the
relevant VMA information.
Second, it's a text based interface, which makes its programmatic use from
applications and libraries more cumbersome and inefficient due to the need
to handle text parsing to get necessary pieces of information. The
overhead is actually payed both by kernel, formatting originally binary
VMA data into text, and then by user space application, parsing it back
into binary data for further use.
For the on-demand pattern of usage, described above, another problem when
writing generic stack trace symbolization library is an unfortunate
performance-vs-correctness tradeoff that needs to be made. Library has to
make a decision to either cache parsed contents of /proc/<pid>/maps (after
initial processing) to service future requests (if application requests to
symbolize another set of addresses (for the same process), captured at
some later time, which is typical for periodic/continuous profiling cases)
to avoid higher costs of re-parsing this file. Or it has to choose to
cache the contents in memory to speed up future requests. In the former
case, more memory is used for the cache and there is a risk of getting
stale data if application loads or unloads shared libraries, or otherwise
changed its set of VMAs somehow, e.g., through additional mmap() calls.
In the latter case, it's the performance hit that comes from re-opening
the file and re-parsing its contents all over again.
This patch aims to solve this problem by providing a new API built on top
of /proc/<pid>/maps. It's meant to address both non-selectiveness and
text nature of /proc/<pid>/maps, by giving user more control of what sort
of VMA(s) needs to be queried, and being binary-based interface eliminates
the overhead of text formatting (on kernel side) and parsing (on user
space side).
It's also designed to be extensible and forward/backward compatible by
including required struct size field, which user has to provide. We use
established copy_struct_from_user() approach to handle extensibility.
User has a choice to pick either getting VMA that covers provided address
or -ENOENT if none is found (exact, least surprising, case). Or, with an
extra query flag (PROCMAP_QUERY_COVERING_OR_NEXT_VMA), they can get either
VMA that covers the address (if there is one), or the closest next VMA
(i.e., VMA with the smallest vm_start > addr). The latter allows more
efficient use, but, given it could be a surprising behavior, requires an
explicit opt-in.
There is another query flag that is useful for some use cases.
PROCMAP_QUERY_FILE_BACKED_VMA instructs this API to only return
file-backed VMAs. Combining this with PROCMAP_QUERY_COVERING_OR_NEXT_VMA
makes it possible to efficiently iterate only file-backed VMAs of the
process, which is what profilers/symbolizers are normally interested in.
All the above querying flags can be combined with (also optional) set of
desired VMA permissions flags. This allows to, for example, iterate only
an executable subset of VMAs, which is what preprocessing pattern, used by
perf tool, would benefit from, as the assumption is that captured stack
traces would have addresses of executable code. This saves time by
skipping non-executable VMAs altogether efficienty.
All these querying flags (modifiers) are orthogonal and can be combined in
a semantically meaningful and natural way.
Basing this ioctl()-based API on top of /proc/<pid>/maps's FD makes sense
given it's querying the same set of VMA data. It's also benefitial
because permission checks for /proc/<pid>/maps is performed at open time
once, and the actual data read of text contents of /proc/<pid>/maps is
done without further permission checks. We piggyback on this pattern with
ioctl()-based API as well, as that's a desired property. Both for
performance reasons, but also for security and flexibility reasons.
Allowing application to open an FD for /proc/self/maps without any extra
capabilities, and then passing it to some sort of profiling agent through
Unix-domain socket, would allow such profiling agent to not require some
of the capabilities that are otherwise expected when opening
/proc/<pid>/maps file for *another* process. This is a desirable property
for some more restricted setups.
This new ioctl-based implementation doesn't interfere with seq_file-based
implementation of /proc/<pid>/maps textual interface, and so could be used
together or independently without paying any price for that.
Note also, that fetching VMA name (e.g., backing file path, or special
hard-coded or user-provided names) is optional just like build ID. If
user sets vma_name_size to zero, kernel code won't attempt to retrieve it,
saving resources.
Earlier versions of this patch set were adding per-VMA locking, which is
why we have a code structure that is ready for abstracting mmap_lock vs
vm_lock differences (query_vma_setup(), query_vma_teardown(), and
query_vma_find_by_addr()), but given anon_vma_name() is not yet compatible
with per-VMA locking, initial implementation sticks to using only
mmap_lock for now. It will be easy to add back per-VMA locking once all
the pieces are ready later on. Which is why we keep existing code
structure with setup/teardown/query helper functions.
[andrii@kernel.org: improve PROCMAP_QUERY's compat mode handling]
Link: https://lkml.kernel.org/r/20240701174805.1897344-2-andrii@kernel.org
Link: https://lkml.kernel.org/r/20240627170900.1672542-3-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "ioctl()-based API to query VMAs from /proc/<pid>/maps", v6.
Implement binary ioctl()-based interface to /proc/<pid>/maps file to allow
applications to query VMA information more efficiently than reading *all*
VMAs nonselectively through text-based interface of /proc/<pid>/maps file.
Patch #2 goes into a lot of details and background on some common patterns
of using /proc/<pid>/maps in the area of performance profiling and
subsequent symbolization of captured stack traces. As mentioned in that
patch, patterns of VMA querying can differ depending on specific use case,
but can generally be grouped into two main categories: the need to query a
small subset of VMAs covering a given batch of addresses, or
reading/storing/caching all (typically, executable) VMAs upfront for later
processing.
The new PROCMAP_QUERY ioctl() API added in this patch set was motivated by
the former pattern of usage. Earlier revisions had a patch adding a tool
that faithfully reproduces an efficient VMA matching pass of a symbolizer,
collecting a subset of covering VMAs for a given set of addresses as
efficiently as possible. This tool served both as a testing ground, as
well as a benchmarking tool. It implements everything both for currently
existing text-based /proc/<pid>/maps interface, as well as for newly-added
PROCMAP_QUERY ioctl(). This revision dropped the tool from the patch set
and, once the API lands upstream, this tool might be added separately on
Github as an example.
Based on discussion on earlier revisions of this patch set, it turned out
that this ioctl() API is competitive with highly-optimized text-based
pre-processing pattern that perf tool is using. Based on perf discussion,
this revision adds more flexibility in specifying a subset of VMAs that
are of interest. Now it's possible to specify desired permissions of VMAs
(e.g., request only executable ones) and/or restrict to only a subset of
VMAs that have file backing. This further improves the efficiency when
using this new API thanks to more selective (executable VMAs only)
querying.
In addition to a custom benchmarking tool, and experimental perf
integration (available at [0]), Daniel Mueller has since also implemented
an experimental integration into blazesym (see [1]), a library used for
stack trace symbolization by our server fleet-wide profiler and another
on-device profiler agent that runs on weaker ARM devices. The latter
ARM-based device profiler is especially sensitive to performance, and so
we benchmarked and compared text-based /proc/<pid>/maps solution to the
equivalent one using PROCMAP_QUERY ioctl().
Results are very encouraging, giving us 5x improvement for end-to-end
so-called "address normalization" pass, which is the part of the
symbolization process that happens locally on ARM device, before being
sent out for further heavier-weight processing on more powerful remote
server. Note that this is not an artificial microbenchmark. It's a full
end-to-end API call being measured with real-world data on real-world
device.
TEXT-BASED
==========
Benchmarking main/normalize_process_no_build_ids_uncached_maps
main/normalize_process_no_build_ids_uncached_maps
time: [49.777 µs 49.982 µs 50.250 µs]
IOCTL-BASED
===========
Benchmarking main/normalize_process_no_build_ids_uncached_maps
main/normalize_process_no_build_ids_uncached_maps
time: [10.328 µs 10.391 µs 10.457 µs]
change: [−79.453% −79.304% −79.166%] (p = 0.00 < 0.02)
Performance has improved.
You can see above that we see the drop from 50µs down to 10µs for
exactly the same amount of work, with the same data and target process.
With the aforementioned custom tool, we see about ~40x improvement (it
might vary a bit, depending on a specific captured set of addresses). And
even for perf-based benchmark it's on par or slightly ahead when using
permission-based filtering (fetching only executable VMAs).
Earlier revisions attempted to use per-VMA locking, if kernel was compiled
with CONFIG_PER_VMA_LOCK=y, but it turned out that anon_vma_name() is not
yet compatible with per-VMA locking and assumes mmap_lock to be taken,
which makes the use of per-VMA locking for this API premature. It was
agreed ([2]) to continue for now with just mmap_lock, but the code
structure is such that it should be easy to add per-VMA locking support
once all the pieces are ready.
One thing that did not change was basing this new API as an ioctl()
command on /proc/<pid>/maps file. An ioctl-based API on top of pidfd was
considered, but has its own downsides. Implementing ioctl() directly on
pidfd will cause access permission checks on every single ioctl(), which
leads to performance concerns and potential spam of capable() audit
messages. It also prevents a nice pattern, possible with
/proc/<pid>/maps, in which application opens /proc/self/maps FD (requiring
no additional capabilities) and passed this FD to profiling agent for
querying. To achieve similar pattern, a new file would have to be created
from pidf just for VMA querying, which is considered to be inferior to
just querying /proc/<pid>/maps FD as proposed in current approach. These
aspects were discussed in the hallway track at recent LSF/MM/BPF 2024 and
sticking to procfs ioctl() was the final agreement we arrived at.
[0] https://github.com/anakryiko/linux/commits/procfs-proc-maps-ioctl-v2/
[1] https://github.com/libbpf/blazesym/pull/675
[2] https://lore.kernel.org/bpf/7rm3izyq2vjp5evdjc7c6z4crdd3oerpiknumdnmmemwyiwx7t@hleldw7iozi3/
This patch (of 6):
Extract generic logic to fetch relevant pieces of data to describe VMA
name. This could be just some string (either special constant or
user-provided), or a string with some formatted wrapping text (e.g.,
"[anon_shmem:<something>]"), or, commonly, file path. seq_file-based
logic has different methods to handle all three cases, but they are
currently mixed in with extracting underlying sources of data.
This patch splits this into data fetching and data formatting, so that
data fetching can be reused later on.
There should be no functional changes.
Link: https://lkml.kernel.org/r/20240627170900.1672542-1-andrii@kernel.org
Link: https://lkml.kernel.org/r/20240627170900.1672542-2-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: remove page_maybe_dma_pinned() and page_mkclean()".
Most page_maybe_dma_pinned() and page_mkclean() callers have been
converted to the folio equivalents, after two more convertsions,
remove them and update the comment and documention.
This patch (of 4):
Convert to use vm_normal_folio() and folio_maybe_dma_pinned() API, which
helps to remove page_maybe_dma_pinned() in the subsequent change.
Link: https://lkml.kernel.org/r/20240604114822.2089819-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20240604114822.2089819-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Helge Deller <deller@gmx.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
... and rename it to folio_precise_page_mapcount(). fs/proc is the last
remaining user, and that should stay that way.
While at it, cleanup kpagecount_read() a bit: there are still some legacy
leftovers -- when the interface was introduced it returned the page
refcount, but was changed briefly afterwards to return the page mapcount.
Further, some simple folio conversion.
Once we stop using the per-page mapcounts of large folios, all
folio_precise_page_mapcount() users will have to implement an alternative
way to achieve what they are trying to achieve, possibly in a less precise
way.
[dan.carpenter@linaro.org: fix uninitialized variable in pagemap_pmd_range()]
Link: https://lkml.kernel.org/r/9d6eaba7-92f8-4a70-8765-38a519680a87@moroto.mountain
Link: https://lkml.kernel.org/r/20240607122357.115423-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
how often"
We currently rely on mapcount information for pages referenced by
non-present entries to calculate the USS (shared vs. private) and the
PSS.
However, relying on mapcounts for non-present entries doesn't make any
sense. We have to treat such entries as "maybe shared, but no idea how
often", implying that they will *not* get accounted towards the USS, and
will get fully accounted to the PSS (no idea how often shared).
There is one exception: device exclusive entries essentially behave like
present entries (e.g., mapcount incremented).
In smaps_pmd_entry(), use is_pfn_swap_entry() instead of
is_migration_entry(), which should not make a real difference but makes
the code look more similar to the PTE variant.
While at it, adjust the comments in smaps_account().
Link: https://lkml.kernel.org/r/20240607122357.115423-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
We added PM_MMAP_EXCLUSIVE in 2015 via commit 77bb499bb60f ("pagemap: add
mmap-exclusive bit for marking pages mapped only here"), when THPs could
not be partially mapped and page_mapcount() returned something that was
true for all pages of the THP.
In 2016, we added support for partially mapping THPs via commit
53f9263baba6 ("mm: rework mapcount accounting to enable 4k mapping of
THPs") but missed to determine PM_MMAP_EXCLUSIVE as well per page.
Checking page_mapcount() on the head page does not tell the whole story.
We should check each individual page. In a future without per-page
mapcounts it will be different, but we'll change that to be consistent
with PTE-mapped THPs once we deal with that.
Link: https://lkml.kernel.org/r/20240607122357.115423-4-david@redhat.com
Fixes: 53f9263baba6 ("mm: rework mapcount accounting to enable 4k mapping of THPs")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Relying on the mapcount for non-present PTEs that reference pages doesn't
make any sense: they are not accounted in the mapcount, so page_mapcount()
== 1 won't return the result we actually want to know.
While we don't check the mapcount for migration entries already, we could
end up checking it for swap, hwpoison, device exclusive, ... entries,
which we really shouldn't.
There is one exception: device private entries, which we consider
fake-present (e.g., incremented the mapcount). But we won't care about
that for now for PM_MMAP_EXCLUSIVE, because indicating PM_SWAP for them
although they are fake-present already sounds suspiciously wrong.
Let's never indicate PM_MMAP_EXCLUSIVE without PM_PRESENT.
Link: https://lkml.kernel.org/r/20240607122357.115423-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "fs/proc: move page_mapcount() to fs/proc/internal.h".
With all other page_mapcount() users in the tree gone, move
page_mapcount() to fs/proc/internal.h, rename it and extend the
documentation to prevent future (ab)use.
... of course, I find some issues while working on that code that I sort
first ;)
We'll now only end up calling page_mapcount() [now
folio_precise_page_mapcount()] on pages mapped via present page table
entries. Except for /proc/kpagecount, that still does questionable
things, but we'll leave that legacy interface as is for now.
Did a quick sanity check. Likely we would want some better selfestest for
/proc/$/pagemap + smaps. I'll see if I can find some time to write some
more.
This patch (of 6):
Looks like we never taught pagemap_pmd_range() about the existence of
PMD-mapped file THPs. Seems to date back to the times when we first added
support for non-anon THPs in the form of shmem THP.
Link: https://lkml.kernel.org/r/20240607122357.115423-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240607122357.115423-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove().
Note that the upper limit of ida_simple_get() is exclusive, but the one of
ida_alloc_max() is inclusive. So a -1 has been added when needed.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/ae10003feb87d240163d0854de95f09e1f00be7d.1717855701.git.christophe.jaillet@wanadoo.fr
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Add sl in /proc/pid/smaps to indicate vma is sealed
Link: https://lkml.kernel.org/r/20240614232014.806352-2-jeffxu@google.com
Fixes: 8be7258aad44 ("mseal: add mseal syscall")
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Röttger <sroettger@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Add a pr_err warning in case a ctl_table is registered with a sentinel
element containing a NULL procname.
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
Remove the mention of a "zero terminated entry" from the
__register_sysctl_table function doc.
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
Erase the code comments mentioning "child" that were forgotten when the
child element was removed in commit 2f2665c13af48 ("sysctl: replace
child with an enumeration").
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
Now that the sentinels have been removed from ctl_table arrays, there is
no need to artificially append empty ctl_table elements at ctl_table
registration. Remove superfluous empty allocation from new_dir and
new_links.
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
The number of ctl_table entries (nr_entries) calculation was previously
based on the ctl_table_size and the sentinel element. Since the
sentinels have been removed, we remove the calculation and just use the
ctl_table_size from the ctl_table_header.
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
Use ARRAY_SIZE exclusively by removing the check to ->procname in the
stopping criteria of the loops traversing ctl_table arrays. This commit
finalizes the removal of the sentinel elements at the end of ctl_table
arrays which reduces the build time size and run time memory bloat by
~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
Remove the entry->procname evaluation from the for loop stopping
criteria in sysctl and sysctl_net.
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.
So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.
Fix it by changing to use atomic_long_t, and the same case with the
mm->ksm_zero_pages.
Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062e01d ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f0704 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
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Move boundary checking for proc_dou8ved_minmax into module loading, thereby
reporting errors in advance. And add a kunit test case ensuring the
boundary check is done correctly.
The boundary check in proc_dou8vec_minmax done to the extra elements in
the ctl_table struct is currently performed at runtime. This allows buggy
kernel modules to be loaded normally without any errors only to fail
when used.
This is a buggy example module:
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sysctl.h>
static struct ctl_table_header *_table_header = NULL;
static unsigned char _data = 0;
struct ctl_table table[] = {
{
.procname = "foo",
.data = &_data,
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE_THOUSAND,
},
};
static int init_demo(void) {
_table_header = register_sysctl("kernel", table);
if (!_table_header)
return -ENOMEM;
return 0;
}
module_init(init_demo);
MODULE_LICENSE("GPL");
And this is the result:
# insmod test.ko
# cat /proc/sys/kernel/foo
cat: /proc/sys/kernel/foo: Invalid argument
Suggested-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Wen Yang <wen.yang@linux.dev>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Joel Granados <j.granados@samsung.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
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Always initialize i_uid/i_gid inside the sysfs core so set_ownership()
can safely skip setting them.
Commit 5ec27ec735ba ("fs/proc/proc_sysctl.c: fix the default values of
i_uid/i_gid on /proc/sys inodes.") added defaults for i_uid/i_gid when
set_ownership() was not implemented. It also missed adjusting
net_ctl_set_ownership() to use the same default values in case the
computation of a better value failed.
Fixes: 5ec27ec735ba ("fs/proc/proc_sysctl.c: fix the default values of i_uid/i_gid on /proc/sys inodes.")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Joel Granados <j.granados@samsung.com>
|
|
After switching smaps_rollup to use VMA iterator, searching for next entry
is part of the condition expression of the do-while loop. So the current
VMA needs to be addressed before the continue statement.
Otherwise, with some VMAs skipped, userspace observed memory
consumption from /proc/pid/smaps_rollup will be smaller than the sum of
the corresponding fields from /proc/pid/smaps.
Link: https://lkml.kernel.org/r/20240523183531.2535436-1-yzhong@purestorage.com
Fixes: c4c84f06285e ("fs/proc/task_mmu: stop using linked list and highest_vm_end")
Signed-off-by: Yuanyuan Zhong <yzhong@purestorage.com>
Reviewed-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Pull misc vfs updates from Al Viro:
"Assorted commits that had missed the last merge window..."
* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
remove call_{read,write}_iter() functions
do_dentry_open(): kill inode argument
kernel_file_open(): get rid of inode argument
get_file_rcu(): no need to check for NULL separately
fd_is_open(): move to fs/file.c
close_on_exec(): pass files_struct instead of fdtable
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-mm updates from Andrew Morton:
"Mainly singleton patches, documented in their respective changelogs.
Notable series include:
- Some maintenance and performance work for ocfs2 in Heming Zhao's
series "improve write IO performance when fragmentation is high".
- Some ocfs2 bugfixes from Su Yue in the series "ocfs2 bugs fixes
exposed by fstests".
- kfifo header rework from Andy Shevchenko in the series "kfifo:
Clean up kfifo.h".
- GDB script fixes from Florian Rommel in the series "scripts/gdb:
Fixes for $lx_current and $lx_per_cpu".
- After much discussion, a coding-style update from Barry Song
explaining one reason why inline functions are preferred over
macros. The series is "codingstyle: avoid unused parameters for a
function-like macro""
* tag 'mm-nonmm-stable-2024-05-19-11-56' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (62 commits)
fs/proc: fix softlockup in __read_vmcore
nilfs2: convert BUG_ON() in nilfs_finish_roll_forward() to WARN_ON()
scripts: checkpatch: check unused parameters for function-like macro
Documentation: coding-style: ask function-like macros to evaluate parameters
nilfs2: use __field_struct() for a bitwise field
selftests/kcmp: remove unused open mode
nilfs2: remove calls to folio_set_error() and folio_clear_error()
kernel/watchdog_perf.c: tidy up kerneldoc
watchdog: allow nmi watchdog to use raw perf event
watchdog: handle comma separated nmi_watchdog command line
nilfs2: make superblock data array index computation sparse friendly
squashfs: remove calls to set the folio error flag
squashfs: convert squashfs_symlink_read_folio to use folio APIs
scripts/gdb: fix detection of current CPU in KGDB
scripts/gdb: make get_thread_info accept pointers
scripts/gdb: fix parameter handling in $lx_per_cpu
scripts/gdb: fix failing KGDB detection during probe
kfifo: don't use "proxy" headers
media: stih-cec: add missing io.h
media: rc: add missing io.h
...
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull mm updates from Andrew Morton:
"The usual shower of singleton fixes and minor series all over MM,
documented (hopefully adequately) in the respective changelogs.
Notable series include:
- Lucas Stach has provided some page-mapping cleanup/consolidation/
maintainability work in the series "mm/treewide: Remove pXd_huge()
API".
- In the series "Allow migrate on protnone reference with
MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
one test.
- In their series "Memory allocation profiling" Kent Overstreet and
Suren Baghdasaryan have contributed a means of determining (via
/proc/allocinfo) whereabouts in the kernel memory is being
allocated: number of calls and amount of memory.
- Matthew Wilcox has provided the series "Various significant MM
patches" which does a number of rather unrelated things, but in
largely similar code sites.
- In his series "mm: page_alloc: freelist migratetype hygiene"
Johannes Weiner has fixed the page allocator's handling of
migratetype requests, with resulting improvements in compaction
efficiency.
- In the series "make the hugetlb migration strategy consistent"
Baolin Wang has fixed a hugetlb migration issue, which should
improve hugetlb allocation reliability.
- Liu Shixin has hit an I/O meltdown caused by readahead in a
memory-tight memcg. Addressed in the series "Fix I/O high when
memory almost met memcg limit".
- In the series "mm/filemap: optimize folio adding and splitting"
Kairui Song has optimized pagecache insertion, yielding ~10%
performance improvement in one test.
- Baoquan He has cleaned up and consolidated the early zone
initialization code in the series "mm/mm_init.c: refactor
free_area_init_core()".
- Baoquan has also redone some MM initializatio code in the series
"mm/init: minor clean up and improvement".
- MM helper cleanups from Christoph Hellwig in his series "remove
follow_pfn".
- More cleanups from Matthew Wilcox in the series "Various
page->flags cleanups".
- Vlastimil Babka has contributed maintainability improvements in the
series "memcg_kmem hooks refactoring".
- More folio conversions and cleanups in Matthew Wilcox's series:
"Convert huge_zero_page to huge_zero_folio"
"khugepaged folio conversions"
"Remove page_idle and page_young wrappers"
"Use folio APIs in procfs"
"Clean up __folio_put()"
"Some cleanups for memory-failure"
"Remove page_mapping()"
"More folio compat code removal"
- David Hildenbrand chipped in with "fs/proc/task_mmu: convert
hugetlb functions to work on folis".
- Code consolidation and cleanup work related to GUP's handling of
hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".
- Rick Edgecombe has developed some fixes to stack guard gaps in the
series "Cover a guard gap corner case".
- Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
series "mm/ksm: fix ksm exec support for prctl".
- Baolin Wang has implemented NUMA balancing for multi-size THPs.
This is a simple first-cut implementation for now. The series is
"support multi-size THP numa balancing".
- Cleanups to vma handling helper functions from Matthew Wilcox in
the series "Unify vma_address and vma_pgoff_address".
- Some selftests maintenance work from Dev Jain in the series
"selftests/mm: mremap_test: Optimizations and style fixes".
- Improvements to the swapping of multi-size THPs from Ryan Roberts
in the series "Swap-out mTHP without splitting".
- Kefeng Wang has significantly optimized the handling of arm64's
permission page faults in the series
"arch/mm/fault: accelerate pagefault when badaccess"
"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"
- GUP cleanups from David Hildenbrand in "mm/gup: consistently call
it GUP-fast".
- hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
path to use struct vm_fault".
- selftests build fixes from John Hubbard in the series "Fix
selftests/mm build without requiring "make headers"".
- Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
series "Improved Memory Tier Creation for CPUless NUMA Nodes".
Fixes the initialization code so that migration between different
memory types works as intended.
- David Hildenbrand has improved follow_pte() and fixed an errant
driver in the series "mm: follow_pte() improvements and acrn
follow_pte() fixes".
- David also did some cleanup work on large folio mapcounts in his
series "mm: mapcount for large folios + page_mapcount() cleanups".
- Folio conversions in KSM in Alex Shi's series "transfer page to
folio in KSM".
- Barry Song has added some sysfs stats for monitoring multi-size
THP's in the series "mm: add per-order mTHP alloc and swpout
counters".
- Some zswap cleanups from Yosry Ahmed in the series "zswap
same-filled and limit checking cleanups".
- Matthew Wilcox has been looking at buffer_head code and found the
documentation to be lacking. The series is "Improve buffer head
documentation".
- Multi-size THPs get more work, this time from Lance Yang. His
series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
optimizes the freeing of these things.
- Kemeng Shi has added more userspace-visible writeback
instrumentation in the series "Improve visibility of writeback".
- Kemeng Shi then sent some maintenance work on top in the series
"Fix and cleanups to page-writeback".
- Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
the series "Improve anon_vma scalability for anon VMAs". Intel's
test bot reported an improbable 3x improvement in one test.
- SeongJae Park adds some DAMON feature work in the series
"mm/damon: add a DAMOS filter type for page granularity access recheck"
"selftests/damon: add DAMOS quota goal test"
- Also some maintenance work in the series
"mm/damon/paddr: simplify page level access re-check for pageout"
"mm/damon: misc fixes and improvements"
- David Hildenbrand has disabled some known-to-fail selftests ni the
series "selftests: mm: cow: flag vmsplice() hugetlb tests as
XFAIL".
- memcg metadata storage optimizations from Shakeel Butt in "memcg:
reduce memory consumption by memcg stats".
- DAX fixes and maintenance work from Vishal Verma in the series
"dax/bus.c: Fixups for dax-bus locking""
* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
selftests: cgroup: add tests to verify the zswap writeback path
mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
mm/damon/core: fix return value from damos_wmark_metric_value
mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
selftests: cgroup: remove redundant enabling of memory controller
Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
Docs/mm/damon/design: use a list for supported filters
Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
selftests/damon: classify tests for functionalities and regressions
selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
selftests/damon: add a test for DAMOS quota goal
...
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git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl
Pull sysctl updates from Joel Granados:
- Remove sentinel elements from ctl_table structs in kernel/*
Removing sentinels in ctl_table arrays reduces the build time size
and runtime memory consumed by ~64 bytes per array. Removals for
net/, io_uring/, mm/, ipc/ and security/ are set to go into mainline
through their respective subsystems making the next release the most
likely place where the final series that removes the check for
proc_name == NULL will land.
This adds to removals already in arch/, drivers/ and fs/.
- Adjust ctl_table definitions and references to allow constification
- Remove unused ctl_table function arguments
- Move non-const elements from ctl_table to ctl_table_header
- Make ctl_table pointers const in ctl_table_root structure
Making the static ctl_table structs const will increase safety by
keeping the pointers to proc_handler functions in .rodata. Though no
ctl_tables where made const in this PR, the ground work for making
that possible has started with these changes sent by Thomas
Weißschuh.
* tag 'sysctl-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
sysctl: drop now unnecessary out-of-bounds check
sysctl: move sysctl type to ctl_table_header
sysctl: drop sysctl_is_perm_empty_ctl_table
sysctl: treewide: constify argument ctl_table_root::permissions(table)
sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)
bpf: Remove the now superfluous sentinel elements from ctl_table array
delayacct: Remove the now superfluous sentinel elements from ctl_table array
kprobes: Remove the now superfluous sentinel elements from ctl_table array
printk: Remove the now superfluous sentinel elements from ctl_table array
scheduler: Remove the now superfluous sentinel elements from ctl_table array
seccomp: Remove the now superfluous sentinel elements from ctl_table array
timekeeping: Remove the now superfluous sentinel elements from ctl_table array
ftrace: Remove the now superfluous sentinel elements from ctl_table array
umh: Remove the now superfluous sentinel elements from ctl_table array
kernel misc: Remove the now superfluous sentinel elements from ctl_table array
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual fses.
Features:
- Free up FMODE_* bits. I've freed up bits 6, 7, 8, and 24. That
means we now have six free FMODE_* bits in total (but bit #6
already got used for FMODE_WRITE_RESTRICTED)
- Add FOP_HUGE_PAGES flag (follow-up to FMODE_* cleanup)
- Add fd_raw cleanup class so we can make use of automatic cleanup
provided by CLASS(fd_raw, f)(fd) for O_PATH fds as well
- Optimize seq_puts()
- Simplify __seq_puts()
- Add new anon_inode_getfile_fmode() api to allow specifying f_mode
instead of open-coding it in multiple places
- Annotate struct file_handle with __counted_by() and use
struct_size()
- Warn in get_file() whether f_count resurrection from zero is
attempted (epoll/drm discussion)
- Folio-sophize aio
- Export the subvolume id in statx() for both btrfs and bcachefs
- Relax linkat(AT_EMPTY_PATH) requirements
- Add F_DUPFD_QUERY fcntl() allowing to compare two file descriptors
for dup*() equality replacing kcmp()
Cleanups:
- Compile out swapfile inode checks when swap isn't enabled
- Use (1 << n) notation for FMODE_* bitshifts for clarity
- Remove redundant variable assignment in fs/direct-io
- Cleanup uses of strncpy in orangefs
- Speed up and cleanup writeback
- Move fsparam_string_empty() helper into header since it's currently
open-coded in multiple places
- Add kernel-doc comments to proc_create_net_data_write()
- Don't needlessly read dentry->d_flags twice
Fixes:
- Fix out-of-range warning in nilfs2
- Fix ecryptfs overflow due to wrong encryption packet size
calculation
- Fix overly long line in xfs file_operations (follow-up to FMODE_*
cleanup)
- Don't raise FOP_BUFFER_{R,W}ASYNC for directories in xfs (follow-up
to FMODE_* cleanup)
- Don't call xfs_file_open from xfs_dir_open (follow-up to FMODE_*
cleanup)
- Fix stable offset api to prevent endless loops
- Fix afs file server rotations
- Prevent xattr node from overflowing the eraseblock in jffs2
- Move fdinfo PTRACE_MODE_READ procfs check into the .permission()
operation instead of .open() operation since this caused userspace
regressions"
* tag 'vfs-6.10.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (39 commits)
afs: Fix fileserver rotation getting stuck
selftests: add F_DUPDFD_QUERY selftests
fcntl: add F_DUPFD_QUERY fcntl()
file: add fd_raw cleanup class
fs: WARN when f_count resurrection is attempted
seq_file: Simplify __seq_puts()
seq_file: Optimize seq_puts()
proc: Move fdinfo PTRACE_MODE_READ check into the inode .permission operation
fs: Create anon_inode_getfile_fmode()
xfs: don't call xfs_file_open from xfs_dir_open
xfs: drop fop_flags for directories
xfs: fix overly long line in the file_operations
shmem: Fix shmem_rename2()
libfs: Add simple_offset_rename() API
libfs: Fix simple_offset_rename_exchange()
jffs2: prevent xattr node from overflowing the eraseblock
vfs, swap: compile out IS_SWAPFILE() on swapless configs
vfs: relax linkat() AT_EMPTY_PATH - aka flink() - requirements
fs/direct-io: remove redundant assignment to variable retval
fs/dcache: Re-use value stored to dentry->d_flags instead of re-reading
...
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While taking a kernel core dump with makedumpfile on a larger system,
softlockup messages often appear.
While softlockup warnings can be harmless, they can also interfere with
things like RCU freeing memory, which can be problematic when the kdump
kexec image is configured with as little memory as possible.
Avoid the softlockup, and give things like work items and RCU a chance to
do their thing during __read_vmcore by adding a cond_resched.
Link: https://lkml.kernel.org/r/20240507091858.36ff767f@imladris.surriel.com
Signed-off-by: Rik van Riel <riel@surriel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Combine the three boolean arguments into one flags argument for
readability.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Let's get rid of another page_mapcount() check and simply use
folio_likely_mapped_shared(), which is precise for hugetlb folios.
While at it, use huge_ptep_get() + pte_page() instead of ptep_get() +
vm_normal_page(), just like we do in pagemap_hugetlb_range().
No functional change intended.
Link: https://lkml.kernel.org/r/20240417092313.753919-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "fs/proc/task_mmu: convert hugetlb functions to work on folis".
Let's convert two more functions, getting rid of two more page_mapcount()
calls.
This patch (of 2):
Let's get rid of another page_mapcount() check and simply use
folio_likely_mapped_shared(), which is precise for hugetlb folios.
While at it, also check for PMD table sharing, like we do in
smaps_hugetlb_range().
No functional change intended, except that we would now detect hugetlb
folios shared via PMD table sharing correctly.
Link: https://lkml.kernel.org/r/20240417092313.753919-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240417092313.753919-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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pagemap_scan_pmd_entry() checks if uffd-wp is set on each pte to avoid
unnecessary if set. However it was previously checking with
`pte_uffd_wp(ptep_get(pte))` without first confirming that the pte was
present. It is only valid to call pte_uffd_wp() for present ptes. For
swap ptes, pte_swp_uffd_wp() must be called because the uffd-wp bit may be
kept in a different position, depending on the arch.
This was leading to test failures in the pagemap_ioctl mm selftest, when
bringing up uffd-wp support on arm64 due to incorrectly interpretting the
uffd-wp status of migration entries.
Let's fix this by using the correct check based on pte_present(). While
we are at it, let's pass the pte to make_uffd_wp_pte() to avoid the
pointless extra ptep_get() which can't be optimized out due to READ_ONCE()
on many arches.
Link: https://lkml.kernel.org/r/20240429114104.182890-1-ryan.roberts@arm.com
Fixes: 12f6b01a0bcb ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS_WRITTEN flag")
Closes: https://lore.kernel.org/linux-arm-kernel/ZiuyGXt0XWwRgFh9@x1n/
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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make_uffd_wp_pte() was previously doing:
pte = ptep_get(ptep);
ptep_modify_prot_start(ptep);
pte = pte_mkuffd_wp(pte);
ptep_modify_prot_commit(ptep, pte);
But if another thread accessed or dirtied the pte between the first 2
calls, this could lead to loss of that information. Since
ptep_modify_prot_start() gets and clears atomically, the following is the
correct pattern and prevents any possible race. Any access after the
first call would see an invalid pte and cause a fault:
pte = ptep_modify_prot_start(ptep);
pte = pte_mkuffd_wp(pte);
ptep_modify_prot_commit(ptep, pte);
Link: https://lkml.kernel.org/r/20240429114017.182570-1-ryan.roberts@arm.com
Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The following commits loosened the permissions of /proc/<PID>/fdinfo/
directory, as well as the files within it, from 0500 to 0555 while also
introducing a PTRACE_MODE_READ check between the current task and
<PID>'s task:
- commit 7bc3fa0172a4 ("procfs: allow reading fdinfo with PTRACE_MODE_READ")
- commit 1927e498aee1 ("procfs: prevent unprivileged processes accessing fdinfo dir")
Before those changes, inode based system calls like inotify_add_watch(2)
would fail when the current task didn't have sufficient read permissions:
[...]
lstat("/proc/1/task/1/fdinfo", {st_mode=S_IFDIR|0500, st_size=0, ...}) = 0
inotify_add_watch(64, "/proc/1/task/1/fdinfo",
IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|
IN_ONLYDIR|IN_DONT_FOLLOW|IN_EXCL_UNLINK) = -1 EACCES (Permission denied)
[...]
This matches the documented behavior in the inotify_add_watch(2) man
page:
ERRORS
EACCES Read access to the given file is not permitted.
After those changes, inotify_add_watch(2) started succeeding despite the
current task not having PTRACE_MODE_READ privileges on the target task:
[...]
lstat("/proc/1/task/1/fdinfo", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
inotify_add_watch(64, "/proc/1/task/1/fdinfo",
IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|
IN_ONLYDIR|IN_DONT_FOLLOW|IN_EXCL_UNLINK) = 1757
openat(AT_FDCWD, "/proc/1/task/1/fdinfo",
O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = -1 EACCES (Permission denied)
[...]
This change in behavior broke .NET prior to v7. See the github link
below for the v7 commit that inadvertently/quietly (?) fixed .NET after
the kernel changes mentioned above.
Return to the old behavior by moving the PTRACE_MODE_READ check out of
the file .open operation and into the inode .permission operation:
[...]
lstat("/proc/1/task/1/fdinfo", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0
inotify_add_watch(64, "/proc/1/task/1/fdinfo",
IN_MODIFY|IN_ATTRIB|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|
IN_ONLYDIR|IN_DONT_FOLLOW|IN_EXCL_UNLINK) = -1 EACCES (Permission denied)
[...]
Reported-by: Kevin Parsons (Microsoft) <parsonskev@gmail.com>
Link: https://github.com/dotnet/runtime/commit/89e5469ac591b82d38510fe7de98346cce74ad4f
Link: https://stackoverflow.com/questions/75379065/start-self-contained-net6-build-exe-as-service-on-raspbian-system-unauthorizeda
Fixes: 7bc3fa0172a4 ("procfs: allow reading fdinfo with PTRACE_MODE_READ")
Cc: stable@vger.kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Hardik Garg <hargar@linux.microsoft.com>
Cc: Allen Pais <apais@linux.microsoft.com>
Signed-off-by: Tyler Hicks (Microsoft) <code@tyhicks.com>
Link: https://lore.kernel.org/r/20240501005646.745089-1-code@tyhicks.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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strncpy() is in the process of being replaced as it is deprecated [1].
We should move towards safer and less ambiguous string interfaces.
Looking at vmcoredd_header's definition:
| struct vmcoredd_header {
| __u32 n_namesz; /* Name size */
| __u32 n_descsz; /* Content size */
| __u32 n_type; /* NT_VMCOREDD */
| __u8 name[8]; /* LINUX\0\0\0 */
| __u8 dump_name[VMCOREDD_MAX_NAME_BYTES]; /* Device dump's name */
| };
.. we see that @name wants to be NUL-padded.
We're copying data->dump_name which is defined as:
| char dump_name[VMCOREDD_MAX_NAME_BYTES]; /* Unique name of the dump */
.. which shares the same size as vdd_hdr->dump_name. Let's make sure we
NUL-pad this as well.
Use strscpy_pad() which NUL-terminates and NUL-pads its destination
buffers. Specifically, use the new 2-argument version of strscpy_pad
introduced in Commit e6584c3964f2f ("string: Allow 2-argument
strscpy()").
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Link: https://lkml.kernel.org/r/20240401-strncpy-fs-proc-vmcore-c-v2-1-dd0a73f42635@google.com
Signed-off-by: Justin Stitt <justinstitt@google.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Replace two calls to compound_head() with one.
Link: https://lkml.kernel.org/r/20240403171456.1445117-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Both callers already have a folio; pass it in instead of doing the
conversion each time.
Link: https://lkml.kernel.org/r/20240403171456.1445117-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Replaces three calls to compound_head() with one. Shrinks the function
from 2614 bytes to 1112 bytes in an allmodconfig build.
Link: https://lkml.kernel.org/r/20240403171456.1445117-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Use folio APIs in procfs".
We're down to very few users of the PageFoo macros, with proc being a
major user.
After this patchset and another patchset I have for khugepaged, we can get
rid of PageActive, PageReadahead and PageSwapBacked. This patchset has
the usual advantages in its own right of removing hidden calls to
compound_head(). We have the page table lock, so the mapcount & refcount
are stable and there can't be any races with folios suddenly becoming tail
pages.
This patch (of 4):
Replaces six calls to compound_head() with one. Shrinks the function from
5054 bytes to 1756 bytes in an allmodconfig build.
Link: https://lkml.kernel.org/r/20240403171456.1445117-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20240403171456.1445117-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Replace seven calls to compound_head() with one.
Link: https://lkml.kernel.org/r/20240402201252.917342-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Remove page_idle and page_young wrappers".
There are only a couple of places left using the page wrappers for idle &
young tracking. Convert the two users in proc and then we can remove the
wrappers. That enables the further simplification of autogenerating the
definitions when CONFIG_PAGE_IDLE_FLAG is disabled.
This patch (of 4):
Replaces four calls to compound_head() with two.
Link: https://lkml.kernel.org/r/20240402201252.917342-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20240402201252.917342-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The mm_struct contains a function pointer *get_unmapped_area(), which is
set to either arch_get_unmapped_area() or arch_get_unmapped_area_topdown()
during the initialization of the mm.
Since the function pointer only ever points to two functions that are
named the same across all arch's, a function pointer is not really
required. In addition future changes will want to add versions of the
functions that take additional arguments. So to save a pointers worth of
bytes in mm_struct, and prevent adding additional function pointers to
mm_struct in future changes, remove it and keep the information about
which get_unmapped_area() to use in a flag.
Add the new flag to MMF_INIT_MASK so it doesn't get clobbered on fork by
mmf_init_flags(). Most MM flags get clobbered on fork. In the
pre-existing behavior mm->get_unmapped_area() would get copied to the new
mm in dup_mm(), so not clobbering the flag preserves the existing behavior
around inheriting the topdown-ness.
Introduce a helper, mm_get_unmapped_area(), to easily convert code that
refers to the old function pointer to instead select and call either
arch_get_unmapped_area() or arch_get_unmapped_area_topdown() based on the
flag. Then drop the mm->get_unmapped_area() function pointer. Leave the
get_unmapped_area() pointer in struct file_operations alone. The main
purpose of this change is to reorganize in preparation for future changes,
but it also converts the calls of mm->get_unmapped_area() from indirect
branches into a direct ones.
The stress-ng bigheap benchmark calls realloc a lot, which calls through
get_unmapped_area() in the kernel. On x86, the change yielded a ~1%
improvement there on a retpoline config.
In testing a few x86 configs, removing the pointer unfortunately didn't
result in any actual size reductions in the compiled layout of mm_struct.
But depending on compiler or arch alignment requirements, the change could
shrink the size of mm_struct.
Link: https://lkml.kernel.org/r/20240326021656.202649-3-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: H. Peter Anvin (Intel) <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Cover a guard gap corner case", v4.
In working on x86’s shadow stack feature, I came across some limitations
around the kernel’s handling of guard gaps. AFAICT these limitations
are not too important for the traditional stack usage of guard gaps, but
have bigger impact on shadow stack’s usage. And now in addition to x86,
we have two other architectures implementing shadow stack like features
that plan to use guard gaps. I wanted to see about addressing them, but I
have not worked on mmap() placement related code before, so would greatly
appreciate if people could take a look and point me in the right
direction.
The nature of the limitations of concern is as follows. In order to ensure
guard gaps between mappings, mmap() would need to consider two things:
1. That the new mapping isn’t placed in an any existing mapping’s guard
gap.
2. That the new mapping isn’t placed such that any existing mappings are
not in *its* guard gaps
Currently mmap never considers (2), and (1) is not considered in some
situations.
When not passing an address hint, or passing one without
MAP_FIXED_NOREPLACE, (1) is enforced. With MAP_FIXED_NOREPLACE, (1) is
not enforced. With MAP_FIXED, (1) is not considered, but this seems to be
expected since MAP_FIXED can already clobber existing mappings. For
MAP_FIXED_NOREPLACE I would have guessed it should respect the guard gaps
of existing mappings, but it is probably a little ambiguous.
In this series I just tried to add enforcement of (2) for the normal (no
address hint) case and only for the newer shadow stack memory (not
stacks). The reason is that with the no-address-hint situation, landing
next to a guard gap could come up naturally and so be more influencable by
attackers such that two shadow stacks could be adjacent without a guard
gap. Where as the address-hint scenarios would require more control -
being able to call mmap() with specific arguments. As for why not just
fix the other corner cases anyway, I thought it might have some greater
possibility of affecting existing apps.
This patch (of 14):
Future changes will perform a treewide change to remove the indirect
branch that is involved in calling mm->get_unmapped_area(). After doing
this, the function will no longer be able to be handled as a function
pointer. To make the treewide change diff cleaner and easier to review,
refactor pde_get_unmapped_area() such that mm->get_unmapped_area() is
called without being stored in a local function pointer. With this in
refactoring, follow on changes will be able to simply replace the call
site with a future function that calls it directly.
Link: https://lkml.kernel.org/r/20240326021656.202649-1-rick.p.edgecombe@intel.com
Link: https://lkml.kernel.org/r/20240326021656.202649-2-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: H. Peter Anvin (Intel) <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This is the folio equivalent of is_huge_zero_page(). It doesn't add any
efficiency, but it does prevent the caller from passing a tail page and
getting confused when the predicate returns false.
Link: https://lkml.kernel.org/r/20240326202833.523759-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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