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Loosely based on a patch from Kees Cook <[email protected]>:
- id and error can be merged
- if operations before ipc_addid() fail, then use call_rcu() directly.
The difference is that call_rcu is used for failures after
security_shm_alloc(), to continue to guaranteed an rcu delay for
security_sem_free().
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Loosely based on a patch from Kees Cook <[email protected]>:
- id and retval can be merged
- if ipc_addid() fails, then use call_rcu() directly.
The difference is that call_rcu is used for failed ipc_addid() calls, to
continue to guaranteed an rcu delay for security_sem_free().
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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No callers remain for ipc_rcu_alloc(). Drop the function.
[[email protected]: Rediff because the memset was temporarily inside ipc_rcu_free()]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Kees Cook <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Instead of using ipc_rcu_alloc() which only performs the refcount bump,
open code it. This also allows for msg_queue structure layout to be
randomized in the future.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Instead of using ipc_rcu_alloc() which only performs the refcount bump,
open code it. This also allows for shmid_kernel structure layout to be
randomized in the future.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Instead of using ipc_rcu_alloc() which only performs the refcount bump,
open code it to perform better sem-specific checks. This also allows
for sem_array structure layout to be randomized in the future.
[[email protected]: Rediff, because the memset was temporarily inside ipc_rcu_alloc()]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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There are no more callers of ipc_rcu_free(), so remove it.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Avoid using ipc_rcu_free, since it just re-finds the original structure
pointer. For the pre-list-init failure path, there is no RCU needed,
since it was just allocated. It can be directly freed.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Avoid using ipc_rcu_free, since it just re-finds the original structure
pointer. For the pre-list-init failure path, there is no RCU needed,
since it was just allocated. It can be directly freed.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Avoid using ipc_rcu_free, since it just re-finds the original structure
pointer. For the pre-list-init failure path, there is no RCU needed,
since it was just allocated. It can be directly freed.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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The only users of ipc_alloc() were ipc_rcu_alloc() and the on-heap
sem_io fall-back memory. Better to just open-code these to make things
easier to read.
[[email protected]: Rediff due to inclusion of memset() into ipc_rcu_alloc()]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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ipc has two management structures that exist for every id:
- struct kern_ipc_perm, it contains e.g. the permissions.
- struct ipc_rcu, it contains the rcu head for rcu handling and the
refcount.
The patch merges both structures.
As a bonus, we may save one cacheline, because both structures are
cacheline aligned. In addition, it reduces the number of casts, instead
most codepaths can use container_of.
To simplify code, the ipc_rcu_alloc initializes the allocation to 0.
[[email protected]: really include the memset() into ipc_alloc_rcu()]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Kees Cook <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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sma->sem_base is initialized with
sma->sem_base = (struct sem *) &sma[1];
The current code has four problems:
- There is an unnecessary pointer dereference - sem_base is not needed.
- Alignment for struct sem only works by chance.
- The current code causes false positive for static code analysis.
- This is a cast between different non-void types, which the future
randstruct GCC plugin warns on.
And, as bonus, the code size gets smaller:
Before:
0 .text 00003770
After:
0 .text 0000374e
[[email protected]: s/[0]/[]/, per hch]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Acked-by: Kees Cook <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Fabian Frederick <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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The retry logic for netlink_attachskb() inside sys_mq_notify()
is nasty and vulnerable:
1) The sock refcnt is already released when retry is needed
2) The fd is controllable by user-space because we already
release the file refcnt
so we when retry but the fd has been just closed by user-space
during this small window, we end up calling netlink_detachskb()
on the error path which releases the sock again, later when
the user-space closes this socket a use-after-free could be
triggered.
Setting 'sock' to NULL here should be sufficient to fix it.
Reported-by: GeneBlue <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Manfred Spraul <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull Writeback error handling fixes from Jeff Layton:
"The main rationale for all of these changes is to tighten up writeback
error reporting to userland. There are many ways now that writeback
errors can be lost, such that fsync/fdatasync/msync return 0 when
writeback actually failed.
This pile contains a small set of cleanups and writeback error
handling fixes that I was able to break off from the main pile (#2).
Two of the patches in this pile are trivial. The exceptions are the
patch to fix up error handling in write_one_page, and the patch to
make JFS pay attention to write_one_page errors"
* tag 'for-linus-v4.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
fs: remove call_fsync helper function
mm: clean up error handling in write_one_page
JFS: do not ignore return code from write_one_page()
mm: drop "wait" parameter from write_one_page()
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Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Carlos Maiolino <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
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... and stop messing with compat_alloc_user_space() and friends
[braino fix from Colin King folded in]
Signed-off-by: Al Viro <[email protected]>
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Patch series "kvmalloc", v5.
There are many open coded kmalloc with vmalloc fallback instances in the
tree. Most of them are not careful enough or simply do not care about
the underlying semantic of the kmalloc/page allocator which means that
a) some vmalloc fallbacks are basically unreachable because the kmalloc
part will keep retrying until it succeeds b) the page allocator can
invoke a really disruptive steps like the OOM killer to move forward
which doesn't sound appropriate when we consider that the vmalloc
fallback is available.
As it can be seen implementing kvmalloc requires quite an intimate
knowledge if the page allocator and the memory reclaim internals which
strongly suggests that a helper should be implemented in the memory
subsystem proper.
Most callers, I could find, have been converted to use the helper
instead. This is patch 6. There are some more relying on __GFP_REPEAT
in the networking stack which I have converted as well and Eric Dumazet
was not opposed [2] to convert them as well.
[1] http://lkml.kernel.org/r/[email protected]
[2] http://lkml.kernel.org/r/1485273626.16328.301.camel@edumazet-glaptop3.roam.corp.google.com
This patch (of 9):
Using kmalloc with the vmalloc fallback for larger allocations is a
common pattern in the kernel code. Yet we do not have any common helper
for that and so users have invented their own helpers. Some of them are
really creative when doing so. Let's just add kv[mz]alloc and make sure
it is implemented properly. This implementation makes sure to not make
a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also
to not warn about allocation failures. This also rules out the OOM
killer as the vmalloc is a more approapriate fallback than a disruptive
user visible action.
This patch also changes some existing users and removes helpers which
are specific for them. In some cases this is not possible (e.g.
ext4_kvmalloc, libcfs_kvzalloc) because those seems to be broken and
require GFP_NO{FS,IO} context which is not vmalloc compatible in general
(note that the page table allocation is GFP_KERNEL). Those need to be
fixed separately.
While we are at it, document that __vmalloc{_node} about unsupported gfp
mask because there seems to be a lot of confusion out there.
kvmalloc_node will warn about GFP_KERNEL incompatible (which are not
superset) flags to catch new abusers. Existing ones would have to die
slowly.
[[email protected]: f2fs fixup]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]> [ext4 part]
Acked-by: Vlastimil Babka <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: David Miller <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Clean up early flag and address some minutia.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull namespace updates from Eric Biederman:
"This is a set of small fixes that were mostly stumbled over during
more significant development. This proc fix and the fix to
posix-timers are the most significant of the lot.
There is a lot of good development going on but unfortunately it
didn't quite make the merge window"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: Fix unbalanced hard link numbers
signal: Make kill_proc_info static
rlimit: Properly call security_task_setrlimit
signal: Remove unused definition of sig_user_definied
ia64: Remove unused IA64_TASK_SIGHAND_OFFSET and IA64_SIGHAND_SIGLOCK_OFFSET
ipc: Remove unused declaration of recompute_msgmni
posix-timers: Correct sanity check in posix_cpu_nsleep
sysctl: Remove dead register_sysctl_root
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The function recompute_msgmni was removed a while ago
but it is still declared in a header file remove it.
Signed-off-by: "Eric W. Biederman" <[email protected]>
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./lib/string.c:134: WARNING: Inline emphasis start-string without end-string.
./mm/filemap.c:522: WARNING: Inline interpreted text or phrase reference start-string without end-string.
./mm/filemap.c:1283: ERROR: Unexpected indentation.
./mm/filemap.c:3003: WARNING: Inline interpreted text or phrase reference start-string without end-string.
./mm/vmalloc.c:1544: WARNING: Inline emphasis start-string without end-string.
./mm/page_alloc.c:4245: ERROR: Unexpected indentation.
./ipc/util.c:676: ERROR: Unexpected indentation.
./drivers/pci/irq.c:35: WARNING: Block quote ends without a blank line; unexpected unindent.
./security/security.c:109: ERROR: Unexpected indentation.
./security/security.c:110: WARNING: Definition list ends without a blank line; unexpected unindent.
./block/genhd.c:275: WARNING: Inline strong start-string without end-string.
./block/genhd.c:283: WARNING: Inline strong start-string without end-string.
./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
./include/linux/clk.h:134: WARNING: Inline emphasis start-string without end-string.
./ipc/util.c:477: ERROR: Unknown target name: "s".
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Acked-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull sched.h split-up from Ingo Molnar:
"The point of these changes is to significantly reduce the
<linux/sched.h> header footprint, to speed up the kernel build and to
have a cleaner header structure.
After these changes the new <linux/sched.h>'s typical preprocessed
size goes down from a previous ~0.68 MB (~22K lines) to ~0.45 MB (~15K
lines), which is around 40% faster to build on typical configs.
Not much changed from the last version (-v2) posted three weeks ago: I
eliminated quirks, backmerged fixes plus I rebased it to an upstream
SHA1 from yesterday that includes most changes queued up in -next plus
all sched.h changes that were pending from Andrew.
I've re-tested the series both on x86 and on cross-arch defconfigs,
and did a bisectability test at a number of random points.
I tried to test as many build configurations as possible, but some
build breakage is probably still left - but it should be mostly
limited to architectures that have no cross-compiler binaries
available on kernel.org, and non-default configurations"
* 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (146 commits)
sched/headers: Clean up <linux/sched.h>
sched/headers: Remove #ifdefs from <linux/sched.h>
sched/headers: Remove the <linux/topology.h> include from <linux/sched.h>
sched/headers, hrtimer: Remove the <linux/wait.h> include from <linux/hrtimer.h>
sched/headers, x86/apic: Remove the <linux/pm.h> header inclusion from <asm/apic.h>
sched/headers, timers: Remove the <linux/sysctl.h> include from <linux/timer.h>
sched/headers: Remove <linux/magic.h> from <linux/sched/task_stack.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/init.h>
sched/core: Remove unused prefetch_stack()
sched/headers: Remove <linux/rculist.h> from <linux/sched.h>
sched/headers: Remove the 'init_pid_ns' prototype from <linux/sched.h>
sched/headers: Remove <linux/signal.h> from <linux/sched.h>
sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>
sched/headers: Remove the runqueue_is_locked() prototype
sched/headers: Remove <linux/sched.h> from <linux/sched/hotplug.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/debug.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/nohz.h>
sched/headers: Remove <linux/sched.h> from <linux/sched/stat.h>
sched/headers: Remove the <linux/gfp.h> include from <linux/sched.h>
sched/headers: Remove <linux/rtmutex.h> from <linux/sched.h>
...
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs pile two from Al Viro:
- orangefs fix
- series of fs/namei.c cleanups from me
- VFS stuff coming from overlayfs tree
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
orangefs: Use RCU for destroy_inode
vfs: use helper for calling f_op->fsync()
mm: use helper for calling f_op->mmap()
vfs: use helpers for calling f_op->{read,write}_iter()
vfs: pass type instead of fn to do_{loop,iter}_readv_writev()
vfs: extract common parts of {compat_,}do_readv_writev()
vfs: wrap write f_ops with file_{start,end}_write()
vfs: deny copy_file_range() for non regular files
vfs: deny fallocate() on directory
vfs: create vfs helper vfs_tmpfile()
namei.c: split unlazy_walk()
namei.c: fold the check for DCACHE_OP_REVALIDATE into d_revalidate()
lookup_fast(): clean up the logics around the fallback to non-rcu mode
namei: fold unlazy_link() into its sole caller
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Overlayfs-related series from Miklos and Amir
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<linux/sched/wake_q.h>
Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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<linux/sched/task.h>
But first update the code that uses these facilities with the
new header.
Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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<linux/sched/user.h>
We are going to split <linux/sched/user.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/user.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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<linux/sched/signal.h>
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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<linux/sched/wake_q.h>
We are going to split <linux/sched/wake_q.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/wake_q.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
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The issue is described here, with a nice testcase:
https://bugzilla.kernel.org/show_bug.cgi?id=192931
The problem is that shmat() calls do_mmap_pgoff() with MAP_FIXED, and
the address rounded down to 0. For the regular mmap case, the
protection mentioned above is that the kernel gets to generate the
address -- arch_get_unmapped_area() will always check for MAP_FIXED and
return that address. So by the time we do security_mmap_addr(0) things
get funky for shmat().
The testcase itself shows that while a regular user crashes, root will
not have a problem attaching a nil-page. There are two possible fixes
to this. The first, and which this patch does, is to simply allow root
to crash as well -- this is also regular mmap behavior, ie when hacking
up the testcase and adding mmap(... |MAP_FIXED). While this approach
is the safer option, the second alternative is to ignore SHM_RND if the
rounded address is 0, thus only having MAP_SHARED flags. This makes the
behavior of shmat() identical to the mmap() case. The downside of this
is obviously user visible, but does make sense in that it maintains
semantics after the round-down wrt 0 address and mmap.
Passes shm related ltp tests.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Reported-by: Gareth Evans <[email protected]>
Cc: Manfred Spraul <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Luc Van Oostenryck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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sysv sem has two lock modes: One with per-semaphore locks, one lock mode
with a single global lock for the whole array. When switching from the
per-semaphore locks to the global lock, all per-semaphore locks must be
scanned for ongoing operations.
The patch adds a hysteresis for switching from the global lock to the
per semaphore locks. This reduces how often the per-semaphore locks
must be scanned.
Compared to the initial patch, this is a simplified solution: Setting
USE_GLOBAL_LOCK_HYSTERESIS to 1 restores the current behavior.
In theory, a workload with exactly 10 simple sops and then one complex
op now scales a bit worse, but this is pure theory: If there is
concurrency, the it won't be exactly 10:1:10:1:10:1:... If there is no
concurrency, then there is no need for scalability.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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a) The ACQUIRE in spin_lock() applies to the read, not to the store, at
least for powerpc. This forces to add a smp_mb() into the fast path.
b) The memory barrier provided by spin_unlock_wait() is right now arch
dependent.
Therefore: Use spin_lock()/spin_unlock() instead of spin_unlock_wait().
Advantage: faster single op semop calls(), observed +8.9% on x86. (the
other solution would be arch dependencies in ipc/sem).
Disadvantage: slower complex op semop calls, if (and only if) there are
no sleeping operations.
The next patch adds hysteresis, this further reduces the probability
that the slow path is used.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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When a non-cooperative userfaultfd monitor copies pages in the
background, it may encounter regions that were already unmapped.
Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely
changes in the virtual memory layout.
Since there might be different uffd contexts for the affected VMAs, we
first should create a temporary representation for the unmap event for
each uffd context and then notify them one by one to the appropriate
userfault file descriptors.
The event notification occurs after the mmap_sem has been released.
[[email protected]: fix nommu build]
Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: fix nommu build]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Michal Hocko <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Hillf Danton <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: "Dr. David Alan Gilbert" <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.
Remove the vma parameter to simplify things.
[[email protected]: fix ARM build]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Ross Zwisler <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Dan Williams <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Signed-off-by: Miklos Szeredi <[email protected]>
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Signed-off-by: Miklos Szeredi <[email protected]>
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Based on the syzcaller test case from dvyukov:
https://gist.githubusercontent.com/dvyukov/d0e5efefe4d7d6daed829f5c3ca26a40/raw/08d0a261fe3c987bed04fbf267e08ba04bd533ea/gistfile1.txt
The slow (i.e.: failure to acquire) syscall exit from semtimedop()
incorrectly assumed that the the same lock is acquired as it was at the
initial syscall entry.
This is wrong:
- thread A: single semop semop(), sleeps
- thread B: multi semop semop(), sleeps
- thread A: woken up by signal/timeout
With this sequence, the initial sem_lock() call locks the per-semaphore
spinlock, and it is unlocked with sem_unlock(). The call at the syscall
return locks the global spinlock. Because locknum is not updated, the
following sem_unlock() call unlocks the per-semaphore spinlock, which is
actually not locked.
The fix is trivial: Use the return value from sem_lock.
Fixes: 370b262c896e ("ipc/sem: avoid idr tree lookup for interrupted semop")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Reported-by: Dmitry Vyukov <[email protected]>
Reported-by: Johanna Abrahamsson <[email protected]>
Tested-by: Johanna Abrahamsson <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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We can avoid the idr tree lookup (albeit possibly avoiding
idr_find_fast()) when being awoken in EINTR, as the semid will not
change in this context while blocked. Use the sma pointer directly and
take the sem_lock, then re-check for RMID races. We continue to
re-check the queue.status with the lock held such that we can detect
situations where we where are dealing with a spurious wakeup but another
task that holds the sem_lock updated the queue.status while we were
spinning for it. Once we take the lock it obviously won't change again.
Being the only caller, get rid of sem_obtain_lock() altogether.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Instead of using the reverse goto, we can simplify the flow and make it
more language natural by just doing do-while instead. One would hope
this is the standard way (or obviously just with a while bucle) that we
do wait/wakeup handling in the kernel. The exact same logic is kept,
just more indented.
[[email protected]: coding-style fixes]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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... saves some LoC and looks cleaner than re-implementing the calls.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Acked-by: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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The compiler already does this, but make it explicit. This helper is
really small and also used in update_queue's main loop, which is O(N^2)
scanning. Inline and avoid the function overhead.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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This is the main workhorse that deals with semop user calls such that
the waitforzero or semval update operations, on the set, can complete on
not as the sma currently stands. Currently, the set is iterated twice
(setting semval, then backwards for the sempid value). Slowpaths, and
particularly SEM_UNDO calls, must undo any altered sem when it is
detected that the caller must block or has errored-out.
With larger sets, there can occur situations where this involves a lot
of cycles and can obviously be a suboptimal use of cached resources in
shared memory. Ie, discarding CPU caches that are also calling semop
and have the sembuf cached (and can complete), while the current lock
holder doing the semop will block, error, or does a waitforzero
operation.
This patch proposes still iterating the set twice, but the first scan is
read-only, and we perform the actual updates afterward, once we know
that the call will succeed. In order to not suffer from the overhead of
dealing with sops that act on the same sem_num, such (rare) cases use
perform_atomic_semop_slow(), which is exactly what we have now.
Duplicates are detected before grabbing sem_lock, and uses simple a
32/64-bit hash array variable to based on the sem_num we are working on.
In addition add some comments to when we expect to the caller to block.
[[email protected]: coding-style fixes]
[[email protected]: ensure we left shift a ULL rather than a 32 bit integer]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Colin Ian King <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Our sysv sems have been using the notion of lockless wakeups for a
while, ever since commit 0a2b9d4c7967 ("ipc/sem.c: move wake_up_process
out of the spinlock section"), in order to reduce the sem_lock hold
times. This in-house pending queue can be replaced by wake_q (just like
all the rest of ipc now), in that it provides the following advantages:
o Simplifies and gets rid of unnecessary code.
o We get rid of the IN_WAKEUP complexities. Given that wake_q_add()
grabs reference to the task, if awoken due to an unrelated event,
between the wake_q_add() and wake_up_q() window, we cannot race with
sys_exit and the imminent call to wake_up_process().
o By not spinning IN_WAKEUP, we no longer need to disable preemption.
In consequence, the wakeup paths (after schedule(), that is) must
acknowledge an external signal/event, as well spurious wakeup occurring
during the pending wakeup window. Obviously no changes in semantics
that could be visible to the user. The fastpath is _only_ for when we
know for sure that we were awoken due to a the waker's successful semop
call (queue.status is not -EINTR).
On a 48-core Haswell, running the ipcscale 'waitforzero' test, the
following is seen with increasing thread counts:
v4.8-rc5 v4.8-rc5
semopv2
Hmean sembench-sem-2 574733.00 ( 0.00%) 578322.00 ( 0.62%)
Hmean sembench-sem-8 811708.00 ( 0.00%) 824689.00 ( 1.59%)
Hmean sembench-sem-12 842448.00 ( 0.00%) 845409.00 ( 0.35%)
Hmean sembench-sem-21 933003.00 ( 0.00%) 977748.00 ( 4.80%)
Hmean sembench-sem-48 935910.00 ( 0.00%) 1004759.00 ( 7.36%)
Hmean sembench-sem-79 937186.00 ( 0.00%) 983976.00 ( 4.99%)
Hmean sembench-sem-234 974256.00 ( 0.00%) 1060294.00 ( 8.83%)
Hmean sembench-sem-265 975468.00 ( 0.00%) 1016243.00 ( 4.18%)
Hmean sembench-sem-296 991280.00 ( 0.00%) 1042659.00 ( 5.18%)
Hmean sembench-sem-327 975415.00 ( 0.00%) 1029977.00 ( 5.59%)
Hmean sembench-sem-358 1014286.00 ( 0.00%) 1049624.00 ( 3.48%)
Hmean sembench-sem-389 972939.00 ( 0.00%) 1043127.00 ( 7.21%)
Hmean sembench-sem-420 981909.00 ( 0.00%) 1056747.00 ( 7.62%)
Hmean sembench-sem-451 990139.00 ( 0.00%) 1051609.00 ( 6.21%)
Hmean sembench-sem-482 965735.00 ( 0.00%) 1040313.00 ( 7.72%)
[[email protected]: coding-style fixes]
[[email protected]: merge fix for WAKE_Q to DEFINE_WAKE_Q rename]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Acked-by: Manfred Spraul <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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obviously be paired with its _prepare()
counterpart. At least whenever possible, as there is no harm in calling
it bogusly as we do now in a few places. Immediate error semop(2) paths
that are far from ever having the task block can be simplified and avoid
a few unnecessary loads on their way out of the call as it is not deeply
nested.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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This patch fixes below warnings:
WARNING: Missing a blank line after declarations
WARNING: Block comments use a trailing */ on a separate line
ERROR: spaces required around that '=' (ctx:WxV)
Above warnings were reported by checkpatch.pl
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Shailesh Pandey <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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When LONG_MIN is passed to msgrcv, one would expect to recieve any
message. But convert_mode does *msgtyp = -*msgtyp and -LONG_MIN is
undefined. In particular, with my gcc -LONG_MIN produces -LONG_MIN
again.
So handle this case properly by assigning LONG_MAX to *msgtyp if
LONG_MIN was specified as msgtyp to msgrcv.
This code:
long msg[] = { 100, 200 };
int m = msgget(IPC_PRIVATE, IPC_CREAT | 0644);
msgsnd(m, &msg, sizeof(msg), 0);
msgrcv(m, &msg, sizeof(msg), LONG_MIN, 0);
produces currently nothing:
msgget(IPC_PRIVATE, IPC_CREAT|0644) = 65538
msgsnd(65538, {100, "\310\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16, 0) = 0
msgrcv(65538, ...
Except a UBSAN warning:
UBSAN: Undefined behaviour in ipc/msg.c:745:13
negation of -9223372036854775808 cannot be represented in type 'long int':
With the patch, I see what I expect:
msgget(IPC_PRIVATE, IPC_CREAT|0644) = 0
msgsnd(0, {100, "\310\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16, 0) = 0
msgrcv(0, {100, "\310\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"}, 16, -9223372036854775808, 0) = 16
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Jiri Slaby <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Currently the wake_q data structure is defined by the WAKE_Q() macro.
This macro, however, looks like a function doing something as "wake" is
a verb. Even checkpatch.pl was confused as it reported warnings like
WARNING: Missing a blank line after declarations
#548: FILE: kernel/futex.c:3665:
+ int ret;
+ WAKE_Q(wake_q);
This patch renames the WAKE_Q() macro to DEFINE_WAKE_Q() which clarifies
what the macro is doing and eliminates the checkpatch.pl warnings.
Signed-off-by: Waiman Long <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ Resolved conflict and added missing rename. ]
Signed-off-by: Ingo Molnar <[email protected]>
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