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Android reported a performance regression in the userfaultfd unmap path.
A closer inspection on the userfaultfd_unmap_prep() change showed that a
second tree walk would be necessary in the reworked code.
Fix the regression by passing each VMA that will be unmapped through to
the userfaultfd_unmap_prep() function as they are added to the unmap list,
instead of re-walking the tree for the VMA.
Link: https://lkml.kernel.org/r/20230601015402.2819343-1-Liam.Howlett@oracle.com
Fixes: 69dbe6daf104 ("userfaultfd: use maple tree iterator to iterate VMAs")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Convert all instances of direct pte_t* dereferencing to instead use
ptep_get() helper. This means that by default, the accesses change from a
C dereference to a READ_ONCE(). This is technically the correct thing to
do since where pgtables are modified by HW (for access/dirty) they are
volatile and therefore we should always ensure READ_ONCE() semantics.
But more importantly, by always using the helper, it can be overridden by
the architecture to fully encapsulate the contents of the pte. Arch code
is deliberately not converted, as the arch code knows best. It is
intended that arch code (arm64) will override the default with its own
implementation that can (e.g.) hide certain bits from the core code, or
determine young/dirty status by mixing in state from another source.
Conversion was done using Coccinelle:
----
// $ make coccicheck \
// COCCI=ptepget.cocci \
// SPFLAGS="--include-headers" \
// MODE=patch
virtual patch
@ depends on patch @
pte_t *v;
@@
- *v
+ ptep_get(v)
----
Then reviewed and hand-edited to avoid multiple unnecessary calls to
ptep_get(), instead opting to store the result of a single call in a
variable, where it is correct to do so. This aims to negate any cost of
READ_ONCE() and will benefit arch-overrides that may be more complex.
Included is a fix for an issue in an earlier version of this patch that
was pointed out by kernel test robot. The issue arose because config
MMU=n elides definition of the ptep helper functions, including
ptep_get(). HUGETLB_PAGE=n configs still define a simple
huge_ptep_clear_flush() for linking purposes, which dereferences the ptep.
So when both configs are disabled, this caused a build error because
ptep_get() is not defined. Fix by continuing to do a direct dereference
when MMU=n. This is safe because for this config the arch code cannot be
trying to virtualize the ptes because none of the ptep helpers are
defined.
Link: https://lkml.kernel.org/r/20230612151545.3317766-4-ryan.roberts@arm.com
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Instead of worrying whether the pmd is stable, userfaultfd_must_wait()
call pte_offset_map() as before, but go back to try again if that fails.
Risk of endless loop? It already broke out if pmd_none(), !pmd_present()
or pmd_trans_huge(), and pte_offset_map() would have cleared pmd_bad():
which leaves pmd_devmap(). Presumably pmd_devmap() is inappropriate in a
vma subject to userfaultfd (it would have been mistreated before), but add
a check just to avoid all possibility of endless loop there.
Link: https://lkml.kernel.org/r/54423f-3dff-fd8d-614a-632727cc4cfb@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm: allow pte_offset_map[_lock]() to fail", v2.
What is it all about? Some mmap_lock avoidance i.e. latency reduction.
Initially just for the case of collapsing shmem or file pages to THPs; but
likely to be relied upon later in other contexts e.g. freeing of empty
page tables (but that's not work I'm doing). mmap_write_lock avoidance
when collapsing to anon THPs? Perhaps, but again that's not work I've
done: a quick attempt was not as easy as the shmem/file case.
I would much prefer not to have to make these small but wide-ranging
changes for such a niche case; but failed to find another way, and have
heard that shmem MADV_COLLAPSE's usefulness is being limited by that
mmap_write_lock it currently requires.
These changes (though of course not these exact patches) have been in
Google's data centre kernel for three years now: we do rely upon them.
What is this preparatory series about?
The current mmap locking will not be enough to guard against that tricky
transition between pmd entry pointing to page table, and empty pmd entry,
and pmd entry pointing to huge page: pte_offset_map() will have to
validate the pmd entry for itself, returning NULL if no page table is
there. What to do about that varies: sometimes nearby error handling
indicates just to skip it; but in many cases an ACTION_AGAIN or "goto
again" is appropriate (and if that risks an infinite loop, then there must
have been an oops, or pfn 0 mistaken for page table, before).
Given the likely extension to freeing empty page tables, I have not
limited this set of changes to a THP config; and it has been easier, and
sets a better example, if each site is given appropriate handling: even
where deeper study might prove that failure could only happen if the pmd
table were corrupted.
Several of the patches are, or include, cleanup on the way; and by the
end, pmd_trans_unstable() and suchlike are deleted: pte_offset_map() and
pte_offset_map_lock() then handle those original races and more. Most
uses of pte_lockptr() are deprecated, with pte_offset_map_nolock() taking
its place.
This patch (of 32):
Use pmdp_get_lockless() in preference to READ_ONCE(*pmdp), to get a more
reliable result with PAE (or READ_ONCE as before without PAE); and remove
the unnecessary extra barrier()s which got left behind in its callers.
HOWEVER: Note the small print in linux/pgtable.h, where it was designed
specifically for fast GUP, and depends on interrupts being disabled for
its full guarantee: most callers which have been added (here and before)
do NOT have interrupts disabled, so there is still some need for caution.
Link: https://lkml.kernel.org/r/f35279a9-9ac0-de22-d245-591afbfb4dc@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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We used to not pass in the pgoff correctly when register/unregister uffd
regions, it caused incorrect behavior on vma merging and can cause
mergeable vmas being separate after ioctls return.
For example, when we have:
vma1(range 0-9, with uffd), vma2(range 10-19, no uffd)
Then someone unregisters uffd on range (5-9), it should logically become:
vma1(range 0-4, with uffd), vma2(range 5-19, no uffd)
But with current code we'll have:
vma1(range 0-4, with uffd), vma3(range 5-9, no uffd), vma2(range 10-19, no uffd)
This patch allows such merge to happen correctly before ioctl returns.
This behavior seems to have existed since the 1st day of uffd. Since
pgoff for vma_merge() is only used to identify the possibility of vma
merging, meanwhile here what we did was always passing in a pgoff smaller
than what we should, so there should have no other side effect besides not
merging it. Let's still tentatively copy stable for this, even though I
don't see anything will go wrong besides vma being split (which is mostly
not user visible).
Link: https://lkml.kernel.org/r/20230517190916.3429499-3-peterx@redhat.com
Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/uffd: Fix vma merge/split", v2.
This series contains two patches that fix vma merge/split for userfaultfd
on two separate issues.
Patch 1 fixes a regression since 6.1+ due to something we overlooked when
converting to maple tree apis. The plan is we use patch 1 to replace the
commit "2f628010799e (mm: userfaultfd: avoid passing an invalid range to
vma_merge())" in mm-hostfixes-unstable tree if possible, so as to bring
uffd vma operations back aligned with the rest code again.
Patch 2 fixes a long standing issue that vma can be left unmerged even if
we can for either uffd register or unregister.
Many thanks to Lorenzo on either noticing this issue from the assert
movement patch, looking at this problem, and also provided a reproducer on
the unmerged vma issue [1].
[1] https://gist.github.com/lorenzo-stoakes/a11a10f5f479e7a977fc456331266e0e
This patch (of 2):
It seems vma merging with uffd paths is broken with either
register/unregister, where right now we can feed wrong parameters to
vma_merge() and it's found by recent patch which moved asserts upwards in
vma_merge() by Lorenzo Stoakes:
https://lore.kernel.org/all/ZFunF7DmMdK05MoF@FVFF77S0Q05N.cambridge.arm.com/
It's possible that "start" is contained within vma but not clamped to its
start. We need to convert this into either "cannot merge" case or "can
merge" case 4 which permits subdivision of prev by assigning vma to prev.
As we loop, each subsequent VMA will be clamped to the start.
This patch will eliminate the report and make sure vma_merge() calls will
become legal again.
One thing to mention is that the "Fixes: 29417d292bd0" below is there only
to help explain where the warning can start to trigger, the real commit to
fix should be 69dbe6daf104. Commit 29417d292bd0 helps us to identify the
issue, but unfortunately we may want to keep it in Fixes too just to ease
kernel backporters for easier tracking.
Link: https://lkml.kernel.org/r/20230517190916.3429499-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20230517190916.3429499-2-peterx@redhat.com
Fixes: 69dbe6daf104 ("userfaultfd: use maple tree iterator to iterate VMAs")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Closes: https://lore.kernel.org/all/ZFunF7DmMdK05MoF@FVFF77S0Q05N.cambridge.arm.com/
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page()
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
rather than exclusive, and has fixed a bunch of errors which were
caused by its unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics
flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim
accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
shmem: restrict noswap option to initial user namespace
mm/khugepaged: fix conflicting mods to collapse_file()
sparse: remove unnecessary 0 values from rc
mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
maple_tree: fix allocation in mas_sparse_area()
mm: do not increment pgfault stats when page fault handler retries
zsmalloc: allow only one active pool compaction context
selftests/mm: add new selftests for KSM
mm: add new KSM process and sysfs knobs
mm: add new api to enable ksm per process
mm: shrinkers: fix debugfs file permissions
mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
migrate_pages_batch: fix statistics for longterm pin retry
userfaultfd: use helper function range_in_vma()
lib/show_mem.c: use for_each_populated_zone() simplify code
mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
fs/buffer: convert create_page_buffers to folio_create_buffers
fs/buffer: add folio_create_empty_buffers helper
...
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git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull sysctl updates from Luis Chamberlain:
"This only does a few sysctl moves from the kernel/sysctl.c file, the
rest of the work has been put towards deprecating two API calls which
incur recursion and prevent us from simplifying the registration
process / saving memory per move. Most of the changes have been
soaking on linux-next since v6.3-rc3.
I've slowed down the kernel/sysctl.c moves due to Matthew Wilcox's
feedback that we should see if we could *save* memory with these moves
instead of incurring more memory. We currently incur more memory since
when we move a syctl from kernel/sysclt.c out to its own file we end
up having to add a new empty sysctl used to register it. To achieve
saving memory we want to allow syctls to be passed without requiring
the end element being empty, and just have our registration process
rely on ARRAY_SIZE(). Without this, supporting both styles of sysctls
would make the sysctl registration pretty brittle, hard to read and
maintain as can be seen from Meng Tang's efforts to do just this [0].
Fortunately, in order to use ARRAY_SIZE() for all sysctl registrations
also implies doing the work to deprecate two API calls which use
recursion in order to support sysctl declarations with subdirectories.
And so during this development cycle quite a bit of effort went into
this deprecation effort. I've annotated the following two APIs are
deprecated and in few kernel releases we should be good to remove
them:
- register_sysctl_table()
- register_sysctl_paths()
During this merge window we should be able to deprecate and unexport
register_sysctl_paths(), we can probably do that towards the end of
this merge window.
Deprecating register_sysctl_table() will take a bit more time but this
pull request goes with a few example of how to do this.
As it turns out each of the conversions to move away from either of
these two API calls *also* saves memory. And so long term, all these
changes *will* prove to have saved a bit of memory on boot.
The way I see it then is if remove a user of one deprecated call, it
gives us enough savings to move one kernel/sysctl.c out from the
generic arrays as we end up with about the same amount of bytes.
Since deprecating register_sysctl_table() and register_sysctl_paths()
does not require maintainer coordination except the final unexport
you'll see quite a bit of these changes from other pull requests, I've
just kept the stragglers after rc3"
Link: https://lkml.kernel.org/r/ZAD+cpbrqlc5vmry@bombadil.infradead.org [0]
* tag 'sysctl-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (29 commits)
fs: fix sysctls.c built
mm: compaction: remove incorrect #ifdef checks
mm: compaction: move compaction sysctl to its own file
mm: memory-failure: Move memory failure sysctls to its own file
arm: simplify two-level sysctl registration for ctl_isa_vars
ia64: simplify one-level sysctl registration for kdump_ctl_table
utsname: simplify one-level sysctl registration for uts_kern_table
ntfs: simplfy one-level sysctl registration for ntfs_sysctls
coda: simplify one-level sysctl registration for coda_table
fs/cachefiles: simplify one-level sysctl registration for cachefiles_sysctls
xfs: simplify two-level sysctl registration for xfs_table
nfs: simplify two-level sysctl registration for nfs_cb_sysctls
nfs: simplify two-level sysctl registration for nfs4_cb_sysctls
lockd: simplify two-level sysctl registration for nlm_sysctls
proc_sysctl: enhance documentation
xen: simplify sysctl registration for balloon
md: simplify sysctl registration
hv: simplify sysctl registration
scsi: simplify sysctl registration with register_sysctl()
csky: simplify alignment sysctl registration
...
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This is a proposal to revert commit 914eedcb9ba0ff53c33808.
I found this when writing a simple UFFDIO_API test to be the first unit
test in this set. Two things breaks with the commit:
- UFFDIO_API check was lost and missing. According to man page, the
kernel should reject ioctl(UFFDIO_API) if uffdio_api.api != 0xaa. This
check is needed if the api version will be extended in the future, or
user app won't be able to identify which is a new kernel.
- Feature flags checks were removed, which means UFFDIO_API with a
feature that does not exist will also succeed. According to the man
page, we should (and it makes sense) to reject ioctl(UFFDIO_API) if
unknown features passed in.
Link: https://lore.kernel.org/r/20220722201513.1624158-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20230412163922.327282-2-peterx@redhat.com
Fixes: 914eedcb9ba0 ("userfaultfd: don't fail on unrecognized features")
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
UFFDIO_COPY already has UFFDIO_COPY_MODE_WP, so when installing a new PTE
to resolve a missing fault, one can install a write-protected one. This
is useful when using UFFDIO_REGISTER_MODE_{MISSING,WP} in combination.
This was motivated by testing HugeTLB HGM [1], and in particular its
interaction with userfaultfd features. Existing userfaultfd code supports
using WP and MINOR modes together (i.e. you can register an area with
both enabled), but without this CONTINUE flag the combination is in
practice unusable.
So, add an analogous UFFDIO_CONTINUE_MODE_WP, which does the same thing as
UFFDIO_COPY_MODE_WP, but for *minor* faults.
Update the selftest to do some very basic exercising of the new flag.
Update Documentation/ to describe how these flags are used (neither the
COPY nor the new CONTINUE versions of this mode flag were described there
before).
[1]: https://patchwork.kernel.org/project/linux-mm/cover/20230218002819.1486479-1-jthoughton@google.com/
Link: https://lkml.kernel.org/r/20230314221250.682452-5-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Many userfaultfd ioctl functions take both a 'mode' and a 'wp_copy'
argument. In future commits we plan to plumb the flags through to more
places, so we'd be proliferating the very long argument list even further.
Let's take the time to simplify the argument list. Combine the two
arguments into one - and generalize, so when we add more flags in the
future, it doesn't imply more function arguments.
Since the modes (copy, zeropage, continue) are mutually exclusive, store
them as an integer value (0, 1, 2) in the low bits. Place combine-able
flag bits in the high bits.
This is quite similar to an earlier patch proposed by Nadav Amit
("userfaultfd: introduce uffd_flags" [1]). The main difference is that
patch only handled flags, whereas this patch *also* combines the "mode"
argument into the same type to shorten the argument list.
[1]: https://lore.kernel.org/all/20220619233449.181323-2-namit@vmware.com/
Link: https://lkml.kernel.org/r/20230314221250.682452-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: James Houghton <jthoughton@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Quite a few userfaultfd functions took both mm and vma pointers as
arguments. Since the mm is trivially accessible via vma->vm_mm, there's
no reason to pass both; it just needlessly extends the already long
argument list.
Get rid of the mm pointer, where possible, to shorten the argument list.
Link: https://lkml.kernel.org/r/20230314221250.682452-3-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: userfaultfd: refactor and add UFFDIO_CONTINUE_MODE_WP",
v5.
- Commits 1-3 refactor userfaultfd ioctl code without behavior changes, with the
main goal of improving consistency and reducing the number of function args.
- Commit 4 adds UFFDIO_CONTINUE_MODE_WP.
This patch (of 4):
The basic problem is, over time we've added new userfaultfd ioctls, and
we've refactored the code so functions which used to handle only one case
are now re-used to deal with several cases. While this happened, we
didn't bother to rename the functions.
Similarly, as we added new functions, we cargo-culted pieces of the
now-inconsistent naming scheme, so those functions too ended up with names
that don't make a lot of sense.
A key point here is, "copy" in most userfaultfd code refers specifically
to UFFDIO_COPY, where we allocate a new page and copy its contents from
userspace. There are many functions with "copy" in the name that don't
actually do this (at least in some cases).
So, rename things into a consistent scheme. The high level idea is that
the call stack for userfaultfd ioctls becomes:
userfaultfd_ioctl
-> userfaultfd_(particular ioctl)
-> mfill_atomic_(particular kind of fill operation)
-> mfill_atomic /* loops over pages in range */
-> mfill_atomic_pte /* deals with single pages */
-> mfill_atomic_pte_(particular kind of fill operation)
-> mfill_atomic_install_pte
There are of course some special cases (shmem, hugetlb), but this is the
general structure which all function names now adhere to.
Link: https://lkml.kernel.org/r/20230314221250.682452-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20230314221250.682452-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/uffd: Add feature bit UFFD_FEATURE_WP_UNPOPULATED", v4.
The new feature bit makes anonymous memory acts the same as file memory on
userfaultfd-wp in that it'll also wr-protect none ptes.
It can be useful in two cases:
(1) Uffd-wp app that needs to wr-protect none ptes like QEMU snapshot,
so pre-fault can be replaced by enabling this flag and speed up
protections
(2) It helps to implement async uffd-wp mode that Muhammad is working on [1]
It's debatable whether this is the most ideal solution because with the
new feature bit set, wr-protect none pte needs to pre-populate the
pgtables to the last level (PAGE_SIZE). But it seems fine so far to
service either purpose above, so we can leave optimizations for later.
The series brings pte markers to anonymous memory too. There's some
change in the common mm code path in the 1st patch, great to have some eye
looking at it, but hopefully they're still relatively straightforward.
This patch (of 2):
This is a new feature that controls how uffd-wp handles none ptes. When
it's set, the kernel will handle anonymous memory the same way as file
memory, by allowing the user to wr-protect unpopulated ptes.
File memories handles none ptes consistently by allowing wr-protecting of
none ptes because of the unawareness of page cache being exist or not.
For anonymous it was not as persistent because we used to assume that we
don't need protections on none ptes or known zero pages.
One use case of such a feature bit was VM live snapshot, where if without
wr-protecting empty ptes the snapshot can contain random rubbish in the
holes of the anonymous memory, which can cause misbehave of the guest when
the guest OS assumes the pages should be all zeros.
QEMU worked it around by pre-populate the section with reads to fill in
zero page entries before starting the whole snapshot process [1].
Recently there's another need raised on using userfaultfd wr-protect for
detecting dirty pages (to replace soft-dirty in some cases) [2]. In that
case if without being able to wr-protect none ptes by default, the dirty
info can get lost, since we cannot treat every none pte to be dirty (the
current design is identify a page dirty based on uffd-wp bit being
cleared).
In general, we want to be able to wr-protect empty ptes too even for
anonymous.
This patch implements UFFD_FEATURE_WP_UNPOPULATED so that it'll make
uffd-wp handling on none ptes being consistent no matter what the memory
type is underneath. It doesn't have any impact on file memories so far
because we already have pte markers taking care of that. So it only
affects anonymous.
The feature bit is by default off, so the old behavior will be maintained.
Sometimes it may be wanted because the wr-protect of none ptes will
contain overheads not only during UFFDIO_WRITEPROTECT (by applying pte
markers to anonymous), but also on creating the pgtables to store the pte
markers. So there's potentially less chance of using thp on the first
fault for a none pmd or larger than a pmd.
The major implementation part is teaching the whole kernel to understand
pte markers even for anonymously mapped ranges, meanwhile allowing the
UFFDIO_WRITEPROTECT ioctl to apply pte markers for anonymous too when the
new feature bit is set.
Note that even if the patch subject starts with mm/uffd, there're a few
small refactors to major mm path of handling anonymous page faults. But
they should be straightforward.
With WP_UNPOPUATED, application like QEMU can avoid pre-read faults all
the memory before wr-protect during taking a live snapshot. Quotting from
Muhammad's test result here [3] based on a simple program [4]:
(1) With huge page disabled
echo madvise > /sys/kernel/mm/transparent_hugepage/enabled
./uffd_wp_perf
Test DEFAULT: 4
Test PRE-READ: 1111453 (pre-fault 1101011)
Test MADVISE: 278276 (pre-fault 266378)
Test WP-UNPOPULATE: 11712
(2) With Huge page enabled
echo always > /sys/kernel/mm/transparent_hugepage/enabled
./uffd_wp_perf
Test DEFAULT: 4
Test PRE-READ: 22521 (pre-fault 22348)
Test MADVISE: 4909 (pre-fault 4743)
Test WP-UNPOPULATE: 14448
There'll be a great perf boost for no-thp case, while for thp enabled with
extreme case of all-thp-zero WP_UNPOPULATED can be slower than MADVISE,
but that's low possibility in reality, also the overhead was not reduced
but postponed until a follow up write on any huge zero thp, so potentially
it is faster by making the follow up writes slower.
[1] https://lore.kernel.org/all/20210401092226.102804-4-andrey.gruzdev@virtuozzo.com/
[2] https://lore.kernel.org/all/Y+v2HJ8+3i%2FKzDBu@x1n/
[3] https://lore.kernel.org/all/d0eb0a13-16dc-1ac1-653a-78b7273781e3@collabora.com/
[4] https://github.com/xzpeter/clibs/blob/master/uffd-test/uffd-wp-perf.c
[peterx@redhat.com: comment changes, oneliner fix to khugepaged]
Link: https://lkml.kernel.org/r/ZB2/8jPhD3fpx5U8@x1n
Link: https://lkml.kernel.org/r/20230309223711.823547-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20230309223711.823547-2-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Paul Gofman <pgofman@codeweavers.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The sysctl_unprivileged_userfaultfd is part of userfaultfd, move it to
its own file.
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
|
|
Replace direct modifications to vma->vm_flags with calls to modifier
functions to be able to track flag changes and to keep vma locking
correctness.
[akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo]
Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Oskolkov <posk@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Drop the vmi_* functions and transition all users to use the vma iterator
directly.
Link: https://lkml.kernel.org/r/20230120162650.984577-30-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Use the vma iterator so that the iterator can be invalidated or updated to
avoid each caller doing so.
Link: https://lkml.kernel.org/r/20230120162650.984577-17-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
huge_pte_offset() is the main walker function for hugetlb pgtables. The
name is not really representing what it does, though.
Instead of renaming it, introduce a wrapper function called hugetlb_walk()
which will use huge_pte_offset() inside. Assert on the locks when walking
the pgtable.
Note, the vma lock assertion will be a no-op for private mappings.
Document the last special case in the page_vma_mapped_walk() path where we
don't need any more lock to call hugetlb_walk().
Taking vma lock there is not needed because either: (1) potential callers
of hugetlb pvmw holds i_mmap_rwsem already (from one rmap_walk()), or (2)
the caller will not walk a hugetlb vma at all so the hugetlb code path not
reachable (e.g. in ksm or uprobe paths).
It's slightly implicit for future page_vma_mapped_walk() callers on that
lock requirement. But anyway, when one day this rule breaks, one will get
a straightforward warning in hugetlb_walk() with lockdep, then there'll be
a way out.
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20221216155229.2043750-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
We can take the hugetlb walker lock, here taking vma lock directly.
Link: https://lkml.kernel.org/r/20221216155217.2043700-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently, we don't enable writenotify when enabling userfaultfd-wp on a
shared writable mapping (for now only shmem and hugetlb). The consequence
is that vma->vm_page_prot will still include write permissions, to be set
as default for all PTEs that get remapped (e.g., mprotect(), NUMA hinting,
page migration, ...).
So far, vma->vm_page_prot is assumed to be a safe default, meaning that we
only add permissions (e.g., mkwrite) but not remove permissions (e.g.,
wrprotect). For example, when enabling softdirty tracking, we enable
writenotify. With uffd-wp on shared mappings, that changed. More details
on vma->vm_page_prot semantics were summarized in [1].
This is problematic for uffd-wp: we'd have to manually check for a uffd-wp
PTEs/PMDs and manually write-protect PTEs/PMDs, which is error prone.
Prone to such issues is any code that uses vma->vm_page_prot to set PTE
permissions: primarily pte_modify() and mk_pte().
Instead, let's enable writenotify such that PTEs/PMDs/... will be mapped
write-protected as default and we will only allow selected PTEs that are
definitely safe to be mapped without write-protection (see
can_change_pte_writable()) to be writable. In the future, we might want
to enable write-bit recovery -- e.g., can_change_pte_writable() -- at more
locations, for example, also when removing uffd-wp protection.
This fixes two known cases:
(a) remove_migration_pte() mapping uffd-wp'ed PTEs writable, resulting
in uffd-wp not triggering on write access.
(b) do_numa_page() / do_huge_pmd_numa_page() mapping uffd-wp'ed PTEs/PMDs
writable, resulting in uffd-wp not triggering on write access.
Note that do_numa_page() / do_huge_pmd_numa_page() can be reached even
without NUMA hinting (which currently doesn't seem to be applicable to
shmem), for example, by using uffd-wp with a PROT_WRITE shmem VMA. On
such a VMA, userfaultfd-wp is currently non-functional.
Note that when enabling userfaultfd-wp, there is no need to walk page
tables to enforce the new default protection for the PTEs: we know that
they cannot be uffd-wp'ed yet, because that can only happen after enabling
uffd-wp for the VMA in general.
Also note that this makes mprotect() on ranges with uffd-wp'ed PTEs not
accidentally set the write bit -- which would result in uffd-wp not
triggering on later write access. This commit makes uffd-wp on shmem
behave just like uffd-wp on anonymous memory in that regard, even though,
mixing mprotect with uffd-wp is controversial.
[1] https://lkml.kernel.org/r/92173bad-caa3-6b43-9d1e-9a471fdbc184@redhat.com
Link: https://lkml.kernel.org/r/20221209080912.7968-1-david@redhat.com
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Ives van Hoorne <ives@codesandbox.io>
Debugged-by: Peter Xu <peterx@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When iterating the VMAs, the maple state needs to be invalidated if the
tree is modified by a split or merge to ensure the maple tree node
contained in the maple state is still valid. These invalidations were
missed, so add them to the paths which alter the tree.
Reported-by: syzbot+0d2014e4da2ccced5b41@syzkaller.appspotmail.com
Fixes: 69dbe6daf104 (userfaultfd: use maple tree iterator to iterate VMAs)
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Anee |
