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This patch allows shmem-backed VMAs to be registered for minor faults.
Minor faults are appropriately relayed to userspace in the fault path, for
VMAs with the relevant flag.
This commit doesn't hook up the UFFDIO_CONTINUE ioctl for shmem-backed
minor faults, though, so userspace doesn't yet have a way to resolve such
faults.
Because of this, we also don't yet advertise this as a supported feature.
That will be done in a separate commit when the feature is fully
implemented.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Acked-by: Peter Xu <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Patch series "userfaultfd: add minor fault handling for shmem", v6.
Overview
========
See the series which added minor faults for hugetlbfs [3] for a detailed
overview of minor fault handling in general. This series adds the same
support for shmem-backed areas.
This series is structured as follows:
- Commits 1 and 2 are cleanups.
- Commits 3 and 4 implement the new feature (minor fault handling for shmem).
- Commit 5 advertises that the feature is now available since at this point it's
fully implemented.
- Commit 6 is a final cleanup, modifying an existing code path to re-use a new
helper we've introduced.
- Commits 7, 8, 9, 10 update the userfaultfd selftest to exercise the feature.
Use Case
========
In some cases it is useful to have VM memory backed by tmpfs instead of
hugetlbfs. So, this feature will be used to support the same VM live
migration use case described in my original series.
Additionally, Android folks (Lokesh Gidra <[email protected]>) hope
to optimize the Android Runtime garbage collector using this feature:
"The plan is to use userfaultfd for concurrently compacting the heap.
With this feature, the heap can be shared-mapped at another location where
the GC-thread(s) could continue the compaction operation without the need
to invoke userfault ioctl(UFFDIO_COPY) each time. OTOH, if and when Java
threads get faults on the heap, UFFDIO_CONTINUE can be used to resume
execution. Furthermore, this feature enables updating references in the
'non-moving' portion of the heap efficiently. Without this feature,
uneccessary page copying (ioctl(UFFDIO_COPY)) would be required."
[1] https://lore.kernel.org/patchwork/cover/1388144/
[2] https://lore.kernel.org/patchwork/patch/1408161/
[3] https://lore.kernel.org/linux-fsdevel/[email protected]/T/#t
This patch (of 9):
Previously, we did a dance where we had one calling path in userfaultfd.c
(mfill_atomic_pte), but then we split it into two in shmem_fs.h
(shmem_{mcopy_atomic,mfill_zeropage}_pte), and then rejoined into a single
shared function in shmem.c (shmem_mfill_atomic_pte).
This is all a bit overly complex. Just call the single combined shmem
function directly, allowing us to clean up various branches, boilerplate,
etc.
While we're touching this function, two other small cleanup changes:
- offset is equivalent to pgoff, so we can get rid of offset entirely.
- Split two VM_BUG_ON cases into two statements. This means the line
number reported when the BUG is hit specifies exactly which condition
was true.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Axel Rasmussen <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Add one anonymous specific test to start using pagemap. With pagemap
support, we can directly read the uffd-wp bit from pgtable without
triggering any fault, so it's easier to do sanity checks in unit tests.
Meanwhile this test also leverages the newly introduced MADV_PAGEOUT
madvise function to test swap ptes with uffd-wp bit set, and across
fork()s.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Export the PTE/PMD status of uffd-wp to pagemap too.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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We should fail uffd-wp registration immediately if the arch does not even
have CONFIG_HAVE_ARCH_USERFAULTFD_WP defined. That'll block also relevant
ioctls on e.g. UFFDIO_WRITEPROTECT because that'll check against
VM_UFFD_WP, which can only be applied with a success registration.
Remove the WP feature bit too for those archs when handling UFFDIO_API
ioctl.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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We tried to do something similar in b569a1760782 ("userfaultfd: wp: drop
_PAGE_UFFD_WP properly when fork") previously, but it's not doing it all
right.. A few fixes around the code path:
1. We were referencing VM_UFFD_WP vm_flags on the _old_ vma rather
than the new vma. That's overlooked in b569a1760782, so it won't work
as expected. Thanks to the recent rework on fork code
(7a4830c380f3a8b3), we can easily get the new vma now, so switch the
checks to that.
2. Dropping the uffd-wp bit in copy_huge_pmd() could be wrong if the
huge pmd is a migration huge pmd. When it happens, instead of using
pmd_uffd_wp(), we should use pmd_swp_uffd_wp(). The fix is simply to
handle them separately.
3. Forget to carry over uffd-wp bit for a write migration huge pmd
entry. This also happens in copy_huge_pmd(), where we converted a
write huge migration entry into a read one.
4. In copy_nonpresent_pte(), drop uffd-wp if necessary for swap ptes.
5. In copy_present_page() when COW is enforced when fork(), we also
need to pass over the uffd-wp bit if VM_UFFD_WP is armed on the new
vma, and when the pte to be copied has uffd-wp bit set.
Remove the comment in copy_present_pte() about this. It won't help a huge
lot to only comment there, but comment everywhere would be an overkill.
Let's assume the commit messages would help.
[[email protected]: fix a few thp pmd missing uffd-wp bit]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: b569a1760782f ("userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork")
Signed-off-by: Peter Xu <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Patch series "mm/uffd: Misc fix for uffd-wp and one more test".
This series tries to fix some corner case bugs for uffd-wp on either thp
or fork(). Then it introduced a new test with pagemap/pageout.
Patch layout:
Patch 1: cleanup for THP, it'll slightly simplify the follow up patches
Patch 2-4: misc fixes for uffd-wp here and there; please refer to each patch
Patch 5: add pagemap support for uffd-wp
Patch 6: add pagemap/pageout test for uffd-wp
The last test introduced can also verify some of the fixes in previous
patches, as the test will fail without the fixes. However it's not easy
to verify all the changes in patch 2-4, but hopefully they can still be
properly reviewed.
Note that if considering the ongoing uffd-wp shmem & hugetlbfs work, patch
5 will be incomplete as it's missing e.g. hugetlbfs part or the special
swap pte detection. However that's not needed in this series, and since
that series is still during review, this series does not depend on that
one (the last test only runs with anonymous memory, not file-backed). So
this series can be merged even before that series.
This patch (of 6):
Huge zero page is handled in a special path in copy_huge_pmd(), however it
should share most codes with a normal thp page. Trying to share more code
with it by removing the special path. The only leftover so far is the
huge zero page refcounting (mm_get_huge_zero_page()), because that's
separately done with a global counter.
This prepares for a future patch to modify the huge pmd to be installed,
so that we don't need to duplicate it explicitly into huge zero page case
too.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Mike Kravetz <[email protected]>, [email protected]
Cc: Mike Rapoport <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Introduce err()/_err() and replace all the different ways to fail the
program, mostly "fprintf" and "perror" with tons of exit() calls. Always
stop the test program at any failure.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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WP and MINOR modes are conditionally enabled on specific memory types.
This patch avoids dumping tons of zeros for those cases when the modes are
not supported at all.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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It tries to check against all zeros and looped for quite a few times.
However after that we'll verify the same page with count_verify, while
count_verify can never be zero. So it means if it's a zero page we'll
detect it anyways with below code.
There's yet another place we conditionally check the fault flag - just do
it unconditionally.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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There seems to have no guarantee that time() will return the same for the
two calls even if there's no delay, e.g. when a fault is accidentally
crossing the changing of a second. Meanwhile, this message is also not
helping that much since delay could happen with a lot of reasons, e.g.,
schedule latency of resolving thread. It may not mean an issue with uffd.
Neither do I saw this error triggered either in the past runs. Even if it
triggers, it'll be drown in all the rest of test logs. Remove it.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Patch series "userfaultfd/selftests: A few cleanups", v2.
I wanted to cleanup userfaultfd.c fault handling for a long time. If it's
not cleaned, when the new code grows the file it'll also grow the size
that needs to be cleaned... This is my attempt to cleanup the userfaultfd
selftest on fault handling, to use an err() macro instead of either
fprintf() or perror() then another exit() call.
The huge cleanup is done in the last patch. The first 4 patches are some
other standalone cleanups for the same file, so I put them together.
This patch (of 5):
Userfaultfd selftest does not need to handle kernel initiated fault. Set
user mode so it can be run even if unprivileged_userfaultfd=0 (which is
the default).
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: Axel Rasmussen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lokesh Gidra <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Upton <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Wang Qing <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Recent changes by patch "mm/page_alloc: allow high-order pages to be
stored on the per-cpu lists" makes kernels determine whether to use pcp by
pcp_allowed_order(), which breaks soft-offline for hugetlb pages.
Soft-offline dissolves a migration source page, then removes it from buddy
free list, so it's assumed that any subpage of the soft-offlined hugepage
are recognized as a buddy page just after returning from
dissolve_free_huge_page(). pcp_allowed_order() returns true for hugetlb,
so this assumption is no longer true.
So disable pcp during dissolve_free_huge_page() and take_page_off_buddy()
to prevent soft-offlined hugepages from linking to pcp lists.
Soft-offline should not be common events so the impact on performance
should be minimal. And I think that the optimization of Mel's patch could
benefit to hugetlb so zone_pcp_disable() is called only in hwpoison
context.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Naoya Horiguchi <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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In [1], Jann Horn points out a possible race between
prep_compound_gigantic_page and __page_cache_add_speculative. The root
cause of the possible race is prep_compound_gigantic_page uncondittionally
setting the ref count of pages to zero. It does this because
prep_compound_gigantic_page is handed a 'group' of pages from an allocator
and needs to convert that group of pages to a compound page. The ref
count of each page in this 'group' is one as set by the allocator.
However, the ref count of compound page tail pages must be zero.
The potential race comes about when ref counted pages are returned from
the allocator. When this happens, other mm code could also take a
reference on the page. __page_cache_add_speculative is one such example.
Therefore, prep_compound_gigantic_page can not just set the ref count of
pages to zero as it does today. Doing so would lose the reference taken
by any other code. This would lead to BUGs in code checking ref counts
and could possibly even lead to memory corruption.
There are two possible ways to address this issue.
1) Make all allocators of gigantic groups of pages be able to return a
properly constructed compound page.
2) Make prep_compound_gigantic_page be more careful when constructing a
compound page.
This patch takes approach 2.
In prep_compound_gigantic_page, use cmpxchg to only set ref count to zero
if it is one. If the cmpxchg fails, call synchronize_rcu() in the hope
that the extra ref count will be driopped during a rcu grace period. This
is not a performance critical code path and the wait should be
accceptable. If the ref count is still inflated after the grace period,
then undo any modifications made and return an error.
Currently prep_compound_gigantic_page is type void and does not return
errors. Modify the two callers to check for and handle error returns. On
error, the caller must free the 'group' of pages as they can not be used
to form a gigantic page. After freeing pages, the runtime caller
(alloc_fresh_huge_page) will retry the allocation once. Boot time
allocations can not be retried.
The routine prep_compound_page also unconditionally sets the ref count of
compound page tail pages to zero. However, in this case the buddy
allocator is constructing a compound page from freshly allocated pages.
The ref count on those freshly allocated pages is already zero, so the
set_page_count(p, 0) is unnecessary and could lead to confusion. Just
remove it.
[1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 58a84aa92723 ("thp: set compound tail page _count to zero")
Signed-off-by: Mike Kravetz <[email protected]>
Reported-by: Jann Horn <[email protected]>
Cc: Youquan Song <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: "Kirill A . Shutemov" <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Muchun Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Patch series "Fix prep_compound_gigantic_page ref count adjustment".
These patches address the possible race between
prep_compound_gigantic_page and __page_cache_add_speculative as described
by Jann Horn in [1].
The first patch simply removes the unnecessary/obsolete helper routine
prep_compound_huge_page to make the actual fix a little simpler.
The second patch is the actual fix and has a detailed explanation in the
commit message.
This potential issue has existed for almost 10 years and I am unaware of
anyone actually hitting the race. I did not cc stable, but would be happy
to squash the patches and send to stable if anyone thinks that is a good
idea.
[1] https://lore.kernel.org/linux-mm/CAG48ez23q0Jy9cuVnwAe7t_fdhMk2S7N5Hdi-GLcCeq5bsfLxw@mail.gmail.com/
This patch (of 2):
I could not think of a reliable way to recreate the issue for testing.
Rather, I 'simulated errors' to exercise all the error paths.
The routine prep_compound_huge_page is a simple wrapper to call either
prep_compound_gigantic_page or prep_compound_page. However, it is only
called from gather_bootmem_prealloc which only processes gigantic pages.
Eliminate the routine and call prep_compound_gigantic_page directly.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Kravetz <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: "Kirill A . Shutemov" <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Youquan Song <[email protected]>
Cc: Muchun Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
When using HUGETLB_PAGE_FREE_VMEMMAP, the freeing unused vmemmap pages
associated with each HugeTLB page is default off. Now the vmemmap is PMD
mapped. So there is no side effect when this feature is enabled with no
HugeTLB pages in the system. Someone may want to enable this feature in
the compiler time instead of using boot command line. So add a config to
make it default on when someone do not want to enable it via command line.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
The preparation of splitting huge PMD mapping of vmemmap pages is ready,
so switch the mapping from PTE to PMD.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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Patch series "Split huge PMD mapping of vmemmap pages", v4.
In order to reduce the difficulty of code review in series[1]. We disable
huge PMD mapping of vmemmap pages when that feature is enabled. In this
series, we do not disable huge PMD mapping of vmemmap pages anymore. We
will split huge PMD mapping when needed. When HugeTLB pages are freed
from the pool we do not attempt coalasce and move back to a PMD mapping
because it is much more complex.
[1] https://lore.kernel.org/linux-doc/[email protected]/
This patch (of 3):
In [1], PMD mappings of vmemmap pages were disabled if the the feature
hugetlb_free_vmemmap was enabled. This was done to simplify the initial
implementation of vmmemap freeing for hugetlb pages. Now, remove this
simplification by allowing PMD mapping and switching to PTE mappings as
needed for allocated hugetlb pages.
When a hugetlb page is allocated, the vmemmap page tables are walked to
free vmemmap pages. During this walk, split huge PMD mappings to PTE
mappings as required. In the unlikely case PTE pages can not be
allocated, return error(ENOMEM) and do not optimize vmemmap of the hugetlb
page.
When HugeTLB pages are freed from the pool, we do not attempt to
coalesce and move back to a PMD mapping because it is much more complex.
[1] https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
On UFFDIO_COPY, if we fail to copy the page contents while holding the
hugetlb_fault_mutex, we will drop the mutex and return to the caller after
allocating a page that consumed a reservation. In this case there may be
a fault that double consumes the reservation. To handle this, we free the
allocated page, fix the reservations, and allocate a temporary hugetlb
page and return that to the caller. When the caller does the copy outside
of the lock, we again check the cache, and allocate a page consuming the
reservation, and copy over the contents.
Test:
Hacked the code locally such that resv_huge_pages underflows produce
a warning and the copy_huge_page_from_user() always fails, then:
./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10
2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success
./tools/testing/selftests/vm/userfaultfd hugetlb 10
2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success
Both tests succeed and produce no warnings. After the
test runs number of free/resv hugepages is correct.
[[email protected]: remove set but not used variable 'vm_alloc_shared']
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix allocation error check and copy func name]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mina Almasry <[email protected]>
Signed-off-by: YueHaibing <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
The debug_cow attribute had been removed since commit 4958e4d86ecb01 ("mm:
thp: remove debug_cow switch"), so remove it in selftest code too,
otherwise the khugepaged test will fail.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 4958e4d86ecb01 ("mm: thp: remove debug_cow switch")
Signed-off-by: Nanyong Sun <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Kefeng Wang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
powerpc 8xx has 4 page sizes:
- 4k
- 16k
- 512k
- 8M
At the time being, vmalloc and vmap only support huge pages which are leaf
at PMD level.
Here the PMD level is 4M, it doesn't correspond to any supported page
size.
For now, implement use of 16k and 512k pages which is done at PTE level.
Support of 8M pages will be implemented later, it requires vmalloc to
support hugepd tables.
Link: https://lkml.kernel.org/r/8b972f1c03fb6bd59953035f0a3e4d26659de4f8.1620795204.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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On some architectures like powerpc, there are huge pages that are mapped
at pte level.
Enable it in vmalloc.
For that, architectures can provide arch_vmap_pte_supported_shift() that
returns the shift for pages to map at pte level.
Link: https://lkml.kernel.org/r/2c717e3b1fba1894d890feb7669f83025bfa314d.1620795204.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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On some architectures like powerpc, there are huge pages that are mapped
at pte level.
Enable it in vmap.
For that, architectures can provide arch_vmap_pte_range_map_size() that
returns the size of pages to map at pte level.
Link: https://lkml.kernel.org/r/fb3ccc73377832ac6708181ec419128a2f98ce36.1620795204.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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For architectures with no PMD and/or no PUD, add stubs similar to what we
have for architectures without P4D.
[[email protected]: arm64: define only {pud/pmd}_{set/clear}_huge when useful]
Link: https://lkml.kernel.org/r/73ec95f40cafbbb69bdfb43a7f53876fd845b0ce.1620990479.git.christophe.leroy@csgroup.eu
[[email protected]: x86: define only {pud/pmd}_{set/clear}_huge when useful]
Link: https://lkml.kernel.org/r/7fbf1b6bc3e15c07c24fa45278d57064f14c896b.1620930415.git.christophe.leroy@csgroup.eu
Link: https://lkml.kernel.org/r/5ac5976419350e8e048d463a64cae449eb3ba4b0.1620795204.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Cc: Naresh Kamboju <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2.
This series implements huge VMAP and VMALLOC on powerpc 8xx.
Powerpc 8xx has 4 page sizes:
- 4k
- 16k
- 512k
- 8M
At the time being, vmalloc and vmap only support huge pages which are
leaf at PMD level.
Here the PMD level is 4M, it doesn't correspond to any supported
page size.
For now, implement use of 16k and 512k pages which is done
at PTE level.
Support of 8M pages will be implemented later, it requires use of
hugepd tables.
To allow this, the architecture provides two functions:
- arch_vmap_pte_range_map_size() which tells vmap_pte_range() what
page size to use. A stub returning PAGE_SIZE is provided when the
architecture doesn't provide this function.
- arch_vmap_pte_supported_shift() which tells __vmalloc_node_range()
what page shift to use for a given area size. A stub returning
PAGE_SHIFT is provided when the architecture doesn't provide this
function.
This patch (of 5):
At the time being, arch_make_huge_pte() has the following prototype:
pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
struct page *page, int writable);
vma is used to get the pages shift or size.
vma is also used on Sparc to get vm_flags.
page is not used.
writable is not used.
In order to use this function without a vma, replace vma by shift and
flags. Also remove the used parameters.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <[email protected]>
Acked-by: Mike Kravetz <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Uladzislau Rezki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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If other processes are mapping any other subpages of the hugepage, i.e.
in pte-mapped thp case, page_mapcount() will return 1 incorrectly. Then
we would discard the page while other processes are still mapping it. Fix
it by using total_mapcount() which can tell whether other processes are
still mapping it.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called")
Reviewed-by: Yang Shi <[email protected]>
Signed-off-by: Miaohe Lin <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Song Liu <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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Commit aa88b68c3b1d ("thp: keep huge zero page pinned until tlb flush")
introduced tlb_remove_page() for huge zero page to keep it pinned until
flush is complete and prevents the page from being split under us. But
huge zero page is kept pinned until all relevant mm_users reach zero since
the commit 6fcb52a56ff6 ("thp: reduce usage of huge zero page's atomic
counter"). So tlb_remove_page_size() for huge zero pmd is unnecessary
now.
Link: https://lkml.kernel.org/r/[email protected]
Reviewed-by: Yang Shi <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Signed-off-by: Miaohe Lin <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Song Liu <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
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transparent_hugepage_enabled()
Since commit 99cb0dbd47a1 ("mm,thp: add read-only THP support for
(non-shmem) FS"), read-only THP file mapping is supported. But it forgot
to add checking for it in transparent_hugepage_enabled(). To fix it, we
add checking for read-only THP file mapping and also introduce helper
transhuge_vma_enabled() to check whether thp is enabled for specified vma
to reduce duplicated code. We rename transparent_hugepage_enabled to
transparent_hugepage_active to make the code easier to follow as suggested
by David Hildenbrand.
[[email protected]: define transhuge_vma_enabled next to transhuge_vma_suitable]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Song Liu <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Now that we can represent the location of ->deferred_list instead of
->mapping + ->index, make use of it to improve readability.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Song Liu <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Patch series "Cleanup and fixup for huge_memory:, v3.
This series contains cleanups to remove dedicated macro and remove
unnecessary tlb_remove_page_size() for huge zero pmd. Also this adds
missing read-only THP checking for transparent_hugepage_enabled() and
avoids discarding hugepage if other processes are mapping it. More
details can be found in the respective changelogs.
Thi patch (of 5):
Rewrite the pgoff checking logic to remove macro HPAGE_CACHE_INDEX_MASK
which is only used here to simplify the code.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
mistake
Remove redundant pfn_{pmd/pte}() in {pmd/pte}_advanced_tests() and adjust
pfn_pud() in pud_advanced_tests() to make it similar with other two
functions.
In addition, the branch condition should be CONFIG_TRANSPARENT_HUGEPAGE
instead of CONFIG_ARCH_HAS_PTE_DEVMAP.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Shixin Liu <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
CONFIG_TRANSPARENT_HUGEPAGE
The functions {pmd/pud}_set_huge and {pmd/pud}_clear_huge are not
dependent on THP. Hence move {pmd/pud}_huge_tests out of
CONFIG_TRANSPARENT_HUGEPAGE.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Shixin Liu <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
All the infrastructure is ready, so we introduce nr_free_vmemmap_pages
field in the hstate to indicate how many vmemmap pages associated with a
HugeTLB page that can be freed to buddy allocator. And initialize it in
the hugetlb_vmemmap_init(). This patch is actual enablement of the
feature.
There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct page
structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, so add a
BUILD_BUG_ON to catch invalid usage of the tail struct page.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Acked-by: Mike Kravetz <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Tested-by: Chen Huang <[email protected]>
Tested-by: Bodeddula Balasubramaniam <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
The parameter of memory_hotplug.memmap_on_memory is not compatible with
hugetlb_free_vmemmap. So disable it when hugetlb_free_vmemmap is enabled.
[[email protected]: remove unneeded include, per Oscar]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Acked-by: Mike Kravetz <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Bodeddula Balasubramaniam <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Add a kernel parameter hugetlb_free_vmemmap to enable the feature of
freeing unused vmemmap pages associated with each hugetlb page on boot.
We disable PMD mapping of vmemmap pages for x86-64 arch when this feature
is enabled. Because vmemmap_remap_free() depends on vmemmap being base
page mapped.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: Barry Song <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Tested-by: Chen Huang <[email protected]>
Tested-by: Bodeddula Balasubramaniam <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
When we free a HugeTLB page to the buddy allocator, we need to allocate
the vmemmap pages associated with it. However, we may not be able to
allocate the vmemmap pages when the system is under memory pressure. In
this case, we just refuse to free the HugeTLB page. This changes behavior
in some corner cases as listed below:
1) Failing to free a huge page triggered by the user (decrease nr_pages).
User needs to try again later.
2) Failing to free a surplus huge page when freed by the application.
Try again later when freeing a huge page next time.
3) Failing to dissolve a free huge page on ZONE_MOVABLE via
offline_pages().
This can happen when we have plenty of ZONE_MOVABLE memory, but
not enough kernel memory to allocate vmemmmap pages. We may even
be able to migrate huge page contents, but will not be able to
dissolve the source huge page. This will prevent an offline
operation and is unfortunate as memory offlining is expected to
succeed on movable zones. Users that depend on memory hotplug
to succeed for movable zones should carefully consider whether the
memory savings gained from this feature are worth the risk of
possibly not being able to offline memory in certain situations.
4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via
alloc_contig_range() - once we have that handling in place. Mainly
affects CMA and virtio-mem.
Similar to 3). virito-mem will handle migration errors gracefully.
CMA might be able to fallback on other free areas within the CMA
region.
Vmemmap pages are allocated from the page freeing context. In order for
those allocations to be not disruptive (e.g. trigger oom killer)
__GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because
a non sleeping allocation would be too fragile and it could fail too
easily under memory pressure. GFP_ATOMIC or other modes to access memory
reserves is not used because we want to prevent consuming reserves under
heavy hugetlb freeing.
[[email protected]: fix dissolve_free_huge_page use of tail/head page]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix alloc_vmemmap_page_list documentation warning]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Signed-off-by: Mike Kravetz <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Bodeddula Balasubramaniam <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
In the subsequent patch, we should allocate the vmemmap pages when freeing
a HugeTLB page. But update_and_free_page() can be called under any
context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However,
we can defer the actual freeing in a kworker to prevent from using
GFP_ATOMIC to allocate the vmemmap pages.
The __update_and_free_page() is where the call to allocate vmemmmap pages
will be inserted.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Bodeddula Balasubramaniam <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Every HugeTLB has more than one struct page structure. We __know__ that
we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to
store metadata associated with each HugeTLB.
There are a lot of struct page structures associated with each HugeTLB
page. For tail pages, the value of compound_head is the same. So we can
reuse first page of tail page structures. We map the virtual addresses of
the remaining pages of tail page structures to the first tail page struct,
and then free these page frames. Therefore, we need to reserve two pages
as vmemmap areas.
When we allocate a HugeTLB page from the buddy, we can free some vmemmap
pages associated with each HugeTLB page. It is more appropriate to do it
in the prep_new_huge_page().
The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages
associated with a HugeTLB page can be freed, returns zero for now, which
means the feature is disabled. We will enable it once all the
infrastructure is there.
[[email protected]: fix documentation warning]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Tested-by: Chen Huang <[email protected]>
Tested-by: Bodeddula Balasubramaniam <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
For HugeTLB page, there are more metadata to save in the struct page. But
the head struct page cannot meet our needs, so we have to abuse other tail
struct page to store the metadata. In order to avoid conflicts caused by
subsequent use of more tail struct pages, we can gather these discrete
indexes of tail struct page. In this case, it will be easier to add a new
tail page index later.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Tested-by: Chen Huang <[email protected]>
Tested-by: Bodeddula Balasubramaniam <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
The option HUGETLB_PAGE_FREE_VMEMMAP allows for the freeing of some
vmemmap pages associated with pre-allocated HugeTLB pages. For example,
on X86_64 6 vmemmap pages of size 4KB each can be saved for each 2MB
HugeTLB page. 4094 vmemmap pages of size 4KB each can be saved for each
1GB HugeTLB page.
When a HugeTLB page is allocated or freed, the vmemmap array representing
the range associated with the page will need to be remapped. When a page
is allocated, vmemmap pages are freed after remapping. When a page is
freed, previously discarded vmemmap pages must be allocated before
remapping.
The config option is introduced early so that supporting code can be
written to depend on the option. The initial version of the code only
provides support for x86-64.
If config HAVE_BOOTMEM_INFO_NODE is enabled, the freeing vmemmap page code
denpend on it to free vmemmap pages. Otherwise, just use
free_reserved_page() to free vmemmmap pages. The routine
register_page_bootmem_info() is used to register bootmem info. Therefore,
make sure register_page_bootmem_info is enabled if
HUGETLB_PAGE_FREE_VMEMMAP is defined.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Acked-by: Mike Kravetz <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Tested-by: Chen Huang <[email protected]>
Tested-by: Bodeddula Balasubramaniam <[email protected]>
Reviewed-by: Balbir Singh <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Patch series "Free some vmemmap pages of HugeTLB page", v23.
This patch series will free some vmemmap pages(struct page structures)
associated with each HugeTLB page when preallocated to save memory.
In order to reduce the difficulty of the first version of code review. In
this version, we disable PMD/huge page mapping of vmemmap if this feature
was enabled. This acutely eliminates a bunch of the complex code doing
page table manipulation. When this patch series is solid, we cam add the
code of vmemmap page table manipulation in the future.
The struct page structures (page structs) are used to describe a physical
page frame. By default, there is an one-to-one mapping from a page frame
to it's corresponding page struct.
The HugeTLB pages consist of multiple base page size pages and is
supported by many architectures. See hugetlbpage.rst in the Documentation
directory for more details. On the x86 architecture, HugeTLB pages of
size 2MB and 1GB are currently supported. Since the base page size on x86
is 4KB, a 2MB HugeTLB page consists of 512 base pages and a 1GB HugeTLB
page consists of 4096 base pages. For each base page, there is a
corresponding page struct.
Within the HugeTLB subsystem, only the first 4 page structs are used to
contain unique information about a HugeTLB page. HUGETLB_CGROUP_MIN_ORDER
provides this upper limit. The only 'useful' information in the remaining
page structs is the compound_head field, and this field is the same for
all tail pages.
By removing redundant page structs for HugeTLB pages, memory can returned
to the buddy allocator for other uses.
When the system boot up, every 2M HugeTLB has 512 struct page structs which
size is 8 pages(sizeof(struct page) * 512 / PAGE_SIZE).
HugeTLB struct pages(8 pages) page frame(8 pages)
+-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+
| | | 0 | -------------> | 0 |
| | +-----------+ +-----------+
| | | 1 | -------------> | 1 |
| | +-----------+ +-----------+
| | | 2 | -------------> | 2 |
| | +-----------+ +-----------+
| | | 3 | -------------> | 3 |
| | +-----------+ +-----------+
| | | 4 | -------------> | 4 |
| 2MB | +-----------+ +-----------+
| | | 5 | -------------> | 5 |
| | +-----------+ +-----------+
| | | 6 | -------------> | 6 |
| | +-----------+ +-----------+
| | | 7 | -------------> | 7 |
| | +-----------+ +-----------+
| |
| |
| |
+-----------+
The value of page->compound_head is the same for all tail pages. The
first page of page structs (page 0) associated with the HugeTLB page
contains the 4 page structs necessary to describe the HugeTLB. The only
use of the remaining pages of page structs (page 1 to page 7) is to point
to page->compound_head. Therefore, we can remap pages 2 to 7 to page 1.
Only 2 pages of page structs will be used for each HugeTLB page. This
will allow us to free the remaining 6 pages to the buddy allocator.
Here is how things look after remapping.
HugeTLB struct pages(8 pages) page frame(8 pages)
+-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+
| | | 0 | -------------> | 0 |
| | +-----------+ +-----------+
| | | 1 | -------------> | 1 |
| | +-----------+ +-----------+
| | | 2 | ----------------^ ^ ^ ^ ^ ^
| | +-----------+ | | | | |
| | | 3 | ------------------+ | | | |
| | +-----------+ | | | |
| | | 4 | --------------------+ | | |
| 2MB | +-----------+ | | |
| | | 5 | ----------------------+ | |
| | +-----------+ | |
| | | 6 | ------------------------+ |
| | +-----------+ |
| | | 7 | --------------------------+
| | +-----------+
| |
| |
| |
+-----------+
When a HugeTLB is freed to the buddy system, we should allocate 6 pages
for vmemmap pages and restore the previous mapping relationship.
Apart from 2MB HugeTLB page, we also have 1GB HugeTLB page. It is similar
to the 2MB HugeTLB page. We also can use this approach to free the
vmemmap pages.
In this case, for the 1GB HugeTLB page, we can save 4094 pages. This is a
very substantial gain. On our server, run some SPDK/QEMU applications
which will use 1024GB HugeTLB page. With this feature enabled, we can
save ~16GB (1G hugepage)/~12GB (2MB hugepage) memory.
Because there are vmemmap page tables reconstruction on the
freeing/allocating path, it increases some overhead. Here are some
overhead analysis.
1) Allocating 10240 2MB HugeTLB pages.
a) With this patch series applied:
# time echo 10240 > /proc/sys/vm/nr_hugepages
real 0m0.166s
user 0m0.000s
sys 0m0.166s
# bpftrace -e 'kprobe:alloc_fresh_huge_page { @start[tid] = nsecs; }
kretprobe:alloc_fresh_huge_page /@start[tid]/ { @latency = hist(nsecs -
@start[tid]); delete(@start[tid]); }'
Attaching 2 probes...
@latency:
[8K, 16K) 5476 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[16K, 32K) 4760 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ |
[32K, 64K) 4 | |
b) Without this patch series:
# time echo 10240 > /proc/sys/vm/nr_hugepages
real 0m0.067s
user 0m0.000s
sys 0m0.067s
# bpftrace -e 'kprobe:alloc_fresh_huge_page { @start[tid] = nsecs; }
kretprobe:alloc_fresh_huge_page /@start[tid]/ { @latency = hist(nsecs -
@start[tid]); delete(@start[tid]); }'
Attaching 2 probes...
@latency:
[4K, 8K) 10147 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[8K, 16K) 93 | |
Summarize: this feature is about ~2x slower than before.
2) Freeing 10240 2MB HugeTLB pages.
a) With this patch series applied:
# time echo 0 > /proc/sys/vm/nr_hugepages
real 0m0.213s
user 0m0.000s
sys 0m0.213s
# bpftrace -e 'kprobe:free_pool_huge_page { @start[tid] = nsecs; }
kretprobe:free_pool_huge_page /@start[tid]/ { @latency = hist(nsecs -
@start[tid]); delete(@start[tid]); }'
Attaching 2 probes...
@latency:
[8K, 16K) 6 | |
[16K, 32K) 10227 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[32K, 64K) 7 | |
b) Without this patch series:
# time echo 0 > /proc/sys/vm/nr_hugepages
real 0m0.081s
user 0m0.000s
sys 0m0.081s
# bpftrace -e 'kprobe:free_pool_huge_page { @start[tid] = nsecs; }
kretprobe:free_pool_huge_page /@start[tid]/ { @latency = hist(nsecs -
@start[tid]); delete(@start[tid]); }'
Attaching 2 probes...
@latency:
[4K, 8K) 6805 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[8K, 16K) 3427 |@@@@@@@@@@@@@@@@@@@@@@@@@@ |
[16K, 32K) 8 | |
Summary: The overhead of __free_hugepage is about ~2-3x slower than before.
Although the overhead has increased, the overhead is not significant.
Like Mike said, "However, remember that the majority of use cases create
HugeTLB pages at or shortly after boot time and add them to the pool. So,
additional overhead is at pool creation time. There is no change to
'normal run time' operations of getting a page from or returning a page to
the pool (think page fault/unmap)".
Despite the overhead and in addition to the memory gains from this series.
The following data is obtained by Joao Martins. Very thanks to his
effort.
There's an additional benefit which is page (un)pinners will see an improvement
and Joao presumes because there are fewer memmap pages and thus the tail/head
pages are staying in cache more often.
Out of the box Joao saw (when comparing linux-next against linux-next +
this series) with gup_test and pinning a 16G HugeTLB file (with 1G pages):
get_user_pages(): ~32k -> ~9k
unpin_user_pages(): ~75k -> ~70k
Usually any tight loop fetching compound_head(), or reading tail pages
data (e.g. compound_head) benefit a lot. There's some unpinning
inefficiencies Joao was fixing[2], but with that in added it shows even
more:
unpin_user_pages(): ~27k -> ~3.8k
[1] https://lore.kernel.org/linux-mm/[email protected]/
[2] https://lore.kernel.org/linux-mm/[email protected]/
This patch (of 9):
Move bootmem info registration common API to individual bootmem_info.c.
And we will use {get,put}_page_bootmem() to initialize the page for the
vmemmap pages or free the vmemmap pages to buddy in the later patch. So
move them out of CONFIG_MEMORY_HOTPLUG_SPARSE. This is just code movement
without any functional change.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Acked-by: Mike Kravetz <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Tested-by: Chen Huang <[email protected]>
Tested-by: Bodeddula Balasubramaniam <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Barry Song <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Cc: Balbir Singh <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"In addition to bug fixes and cleanups, there are two new features for
ext4 in 5.14:
- Allow applications to poll on changes to
/sys/fs/ext4/*/errors_count
- Add the ioctl EXT4_IOC_CHECKPOINT which allows the journal to be
checkpointed, truncated and discarded or zero'ed"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (32 commits)
jbd2: export jbd2_journal_[un]register_shrinker()
ext4: notify sysfs on errors_count value change
fs: remove bdev_try_to_free_page callback
ext4: remove bdev_try_to_free_page() callback
jbd2: simplify journal_clean_one_cp_list()
jbd2,ext4: add a shrinker to release checkpointed buffers
jbd2: remove redundant buffer io error checks
jbd2: don't abort the journal when freeing buffers
jbd2: ensure abort the journal if detect IO error when writing original buffer back
jbd2: remove the out label in __jbd2_journal_remove_checkpoint()
ext4: no need to verify new add extent block
jbd2: clean up misleading comments for jbd2_fc_release_bufs
ext4: add check to prevent attempting to resize an fs with sparse_super2
ext4: consolidate checks for resize of bigalloc into ext4_resize_begin
ext4: remove duplicate definition of ext4_xattr_ibody_inline_set()
ext4: fsmap: fix the block/inode bitmap comment
ext4: fix comment for s_hash_unsigned
ext4: use local variable ei instead of EXT4_I() macro
ext4: fix avefreec in find_group_orlov
ext4: correct the cache_nr in tracepoint ext4_es_shrink_exit
...
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- Various DM persistent-data library improvements and fixes that
benefit both the DM thinp and cache targets.
- A few small DM kcopyd efficiency improvements.
- Significant zoned related block core, DM core and DM zoned target
changes that culminate with adding zoned append emulation (which is
required to properly fix DM crypt's zoned support).
- Various DM writecache target changes that improve efficiency. Adds an
optional "metadata_only" feature that only promotes bios flagged with
REQ_META. But the most significant improvement is writecache's
ability to pause writeback, for a confiurable time, if/when the
working set is larger than the cache (and the cache is full) -- this
ensures performance is no worse than the slower origin device.
* tag 'for-5.14/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (35 commits)
dm writecache: make writeback pause configurable
dm writecache: pause writeback if cache full and origin being written directly
dm io tracker: factor out IO tracker
dm btree remove: assign new_root only when removal succeeds
dm zone: fix dm_revalidate_zones() memory allocation
dm ps io affinity: remove redundant continue statement
dm writecache: add optional "metadata_only" parameter
dm writecache: add "cleaner" and "max_age" to Documentation
dm writecache: write at least 4k when committing
dm writecache: flush origin device when writing and cache is full
dm writecache: have ssd writeback wait if the kcopyd workqueue is busy
dm writecache: use list_move instead of list_del/list_add in writecache_writeback()
dm writecache: commit just one block, not a full page
dm writecache: remove unused gfp_t argument from wc_add_block()
dm crypt: Fix zoned block device support
dm: introduce zone append emulation
dm: rearrange core declarations for extended use from dm-zone.c
block: introduce BIO_ZONE_WRITE_LOCKED bio flag
block: introduce bio zone helpers
block: improve handling of all zones reset operation
...
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git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core:
- BPF:
- add syscall program type and libbpf support for generating
instructions and bindings for in-kernel BPF loaders (BPF loaders
for BPF), this is a stepping stone for signed BPF programs
- infrastructure to migrate TCP child sockets from one listener to
another in the same reuseport group/map to improve flexibility
of service hand-off/restart
- add broadcast support to XDP redirect
- allow bypass of the lockless qdisc to improving performance (for
pktgen: +23% with one thread, +44% with 2 threads)
- add a simpler version of "DO_ONCE()" which does not require jump
labels, intended for slow-path usage
- virtio/vsock: introduce SOCK_SEQPACKET support
- add getsocketopt to retrieve netns cookie
- ip: treat lowest address of a IPv4 subnet as ordinary unicast
address allowing reclaiming of precious IPv4 addresses
- ipv6: use prandom_u32() for ID generation
- ip: add support for more flexible field selection for hashing
across multi-path routes (w/ offload to mlxsw)
- icmp: add support for extended RFC 8335 PROBE (ping)
- seg6: add support for SRv6 End.DT46 behavior
- mptcp:
- DSS checksum support (RFC 8684) to detect middlebox meddling
- support Connection-time 'C' flag
- time stamping support
- sctp: packetization Layer Path MTU Discovery (RFC 8899)
- xfrm: speed up state addition with seq set
- WiFi:
- hidden AP discovery on 6 GHz and other HE 6 GHz improvements
- aggregation handling improvements for some drivers
- minstrel improvements for no-ack frames
- deferred rate control for TXQs to improve reaction times
- switch from round robin to virtual time-based airtime scheduler
- add trace points:
- tcp checksum errors
- openvswitch - action execution, upcalls
- socket errors via sk_error_report
Device APIs:
- devlink: add rate API for hierarchical control of max egress rate
of virtual devices (VFs, SFs etc.)
- don't require RCU read lock to be held around BPF hooks in NAPI
context
- page_pool: generic buffer recycling
New hardware/drivers:
- mobile:
- iosm: PCIe Driver for Intel M.2 Modem
- support for Qualcomm MSM8998 (ipa)
- WiFi: Qualcomm QCN9074 and WCN6855 PCI devices
- sparx5: Microchip SparX-5 family of Enterprise Ethernet switches
- Mellanox BlueField Gigabit Ethernet (control NIC of the DPU)
- NXP SJA1110 Automotive Ethernet 10-port switch
- Qualcomm QCA8327 switch support (qca8k)
- Mikrotik 10/25G NIC (atl1c)
Driver changes:
- ACPI support for some MDIO, MAC and PHY devices from Marvell and
NXP (our first foray into MAC/PHY description via ACPI)
- HW timestamping (PTP) support: bnxt_en, ice, sja1105, hns3, tja11xx
- Mellanox/Nvidia NIC (mlx5)
- NIC VF offload of L2 bridging
- support IRQ distribution to Sub-functions
- Marvell (prestera):
- add flower and match all
- devlink trap
- link aggregation
- Netronome (nfp): connection tracking offload
- Intel 1GE (igc): add AF_XDP support
- Marvell DPU (octeontx2): ingress ratelimit offload
- Google vNIC (gve): new ring/descriptor format support
- Qualcomm mobile (rmnet & ipa): inline checksum offload support
- MediaTek WiFi (mt76)
- mt7915 MSI support
- mt7915 Tx status reporting
- mt7915 thermal sensors support
- mt7921 decapsulation offload
- mt7921 enable runtime pm and deep sleep
- Realtek WiFi (rtw88)
- beacon filter support
- Tx antenna path diversity support
- firmware crash information via devcoredump
- Qualcomm WiFi (wcn36xx)
- Wake-on-WLAN support with magic packets and GTK rekeying
- Micrel PHY (ksz886x/ksz8081): add cable test support"
* tag 'net-next-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2168 commits)
tcp: change ICSK_CA_PRIV_SIZE definition
tcp_yeah: check struct yeah size at compile time
gve: DQO: Fix off by one in gve_rx_dqo()
stmmac: intel: set PCI_D3hot in suspend
stmmac: intel: Enable PHY WOL option in EHL
net: stmmac: option to enable PHY WOL with PMT enabled
net: say "local" instead of "static" addresses in ndo_dflt_fdb_{add,del}
net: use netdev_info in ndo_dflt_fdb_{add,del}
ptp: Set lookup cookie when creating a PTP PPS source.
net: sock: add trace for socket errors
net: sock: introduce sk_error_report
net: dsa: replay the local bridge FDB entries pointing to the bridge dev too
net: dsa: ensure during dsa_fdb_offload_notify that dev_hold and dev_put are on the same dev
net: dsa: include fdb entries pointing to bridge in the host fdb list
net: dsa: include bridge addresses which are local in the host fdb list
net: dsa: sync static FDB entries on foreign interfaces to hardware
net: dsa: install the host MDB and FDB entries in the master's RX filter
net: dsa: reference count the FDB addresses at the cross-chip notifier level
net: dsa: introduce a separate cross-chip notifier type for host FDBs
net: dsa: reference count the MDB entries at the cross-chip notifier level
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
- Fix a small inconsistency (bug) in load tracking, caught by a new
warning that several people reported.
- Flip CONFIG_SCHED_CORE to default-disabled, and update the Kconfig
help text.
* tag 'sched-urgent-2021-06-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Disable CONFIG_SCHED_CORE by default
sched/fair: Ensure _sum and _avg values stay consistent
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Pull microblaze updates from Michal Simek:
- Remove unused PAGE_UP/DOWN macros
- Fix trivial spelling mistake
* tag 'microblaze-v5.14' of git://git.monstr.eu/linux-2.6-microblaze:
arch: microblaze: Fix spelling mistake "vesion" -> "version"
microblaze: Cleanup unused functions
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Pull SafeSetID update from Micah Morton:
"One very minor code cleanup change that marks a variable as
__initdata"
* tag 'safesetid-5.14' of git://github.com/micah-morton/linux:
LSM: SafeSetID: Mark safesetid_initialized as __initdata
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Pull smack updates from Casey Schaufler:
"There is nothing more significant than an improvement to a byte count
check in smackfs.
All changes have been in next for weeks"
* tag 'Smack-for-5.14' of git://github.com/cschaufler/smack-next:
Smack: fix doc warning
Revert "Smack: Handle io_uring kernel thread privileges"
smackfs: restrict bytes count in smk_set_cipso()
security/smack/: fix misspellings using codespell tool
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
Pull audit updates from Paul Moore:
"Another merge window, another small audit pull request.
Four patches in total: one is cosmetic, one removes an unnecessary
initialization, one renames some enum values to prevent name
collisions, and one converts list_del()/list_add() to list_move().
None of these are earth shattering and all pass the audit-testsuite
tests while merging cleanly on top of your tree from earlier today"
* tag 'audit-pr-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
audit: remove unnecessary 'ret' initialization
audit: remove trailing spaces and tabs
audit: Use list_move instead of list_del/list_add
audit: Rename enum audit_state constants to avoid AUDIT_DISABLED redefinition
audit: add blank line after variable declarations
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull SELinux updates from Paul Moore:
- The slow_avc_audit() function is now non-blocking so we can remove
the AVC_NONBLOCKING tricks; this also includes the 'flags' variant of
avc_has_perm().
- Use kmemdup() instead of kcalloc()+copy when copying parts of the
SELinux policydb.
- The InfiniBand device name is now passed by reference when possible
in the SELinux code, removing a strncpy().
- Minor cleanups including: constification of avtab function args,
removal of useless LSM/XFRM function args, SELinux kdoc fixes, and
removal of redundant assignments.
* tag 'selinux-pr-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: kill 'flags' argument in avc_has_perm_flags() and avc_audit()
selinux: slow_avc_audit has become non-blocking
selinux: Fix kernel-doc
selinux: use __GFP_NOWARN with GFP_NOWAIT in the AVC
lsm_audit,selinux: pass IB device name by reference
selinux: Remove redundant assignment to rc
selinux: Corrected comment to match kernel-doc comment
selinux: delete selinux_xfrm_policy_lookup() useless argument
selinux: constify some avtab function arguments
selinux: simplify duplicate_policydb_cond_list() by using kmemdup()
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