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Since general RCU GUP fast was introduced in commit 2667f50e8b81 ("mm:
introduce a general RCU get_user_pages_fast()"), a TLB flush is no longer
sufficient to handle concurrent GUP-fast in all cases, it only handles
traditional IPI-based GUP-fast correctly. On architectures that send an
IPI broadcast on TLB flush, it works as expected. But on the
architectures that do not use IPI to broadcast TLB flush, it may have the
below race:
CPU A CPU B
THP collapse fast GUP
gup_pmd_range() <-- see valid pmd
gup_pte_range() <-- work on pte
pmdp_collapse_flush() <-- clear pmd and flush
__collapse_huge_page_isolate()
check page pinned <-- before GUP bump refcount
pin the page
check PTE <-- no change
__collapse_huge_page_copy()
copy data to huge page
ptep_clear()
install huge pmd for the huge page
return the stale page
discard the stale page
The race can be fixed by checking whether PMD is changed or not after
taking the page pin in fast GUP, just like what it does for PTE. If the
PMD is changed it means there may be parallel THP collapse, so GUP should
back off.
Also update the stale comment about serializing against fast GUP in
khugepaged.
Link: https://lkml.kernel.org/r/20220907180144.555485-1-shy828301@gmail.com
Fixes: 2667f50e8b81 ("mm: introduce a general RCU get_user_pages_fast()")
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
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/vbabka/slab
Pull slab fixes from Vlastimil Babka:
- Fix a possible use-after-free in SLUB's kmem_cache removal,
introduced in this cycle, by Feng Tang.
- WQ_MEM_RECLAIM dependency fix for the workqueue-based cpu slab
flushing introduced in 5.15, by Maurizio Lombardi.
- Add missing KASAN hooks in two kmalloc entry paths, by Peter
Collingbourne.
- A BUG_ON() removal in SLUB's kmem_cache creation when allocation
fails (too small to possibly happen in practice, syzbot used fault
injection), by Chao Yu.
* tag 'slab-for-6.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm: slub: fix flush_cpu_slab()/__free_slab() invocations in task context.
mm/slab_common: fix possible double free of kmem_cache
kasan: call kasan_malloc() from __kmalloc_*track_caller()
mm/slub: fix to return errno if kmalloc() fails
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Commit 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations
__free_slab() invocations out of IRQ context") moved all flush_cpu_slab()
invocations to the global workqueue to avoid a problem related
with deactivate_slab()/__free_slab() being called from an IRQ context
on PREEMPT_RT kernels.
When the flush_all_cpu_locked() function is called from a task context
it may happen that a workqueue with WQ_MEM_RECLAIM bit set ends up
flushing the global workqueue, this will cause a dependency issue.
workqueue: WQ_MEM_RECLAIM nvme-delete-wq:nvme_delete_ctrl_work [nvme_core]
is flushing !WQ_MEM_RECLAIM events:flush_cpu_slab
WARNING: CPU: 37 PID: 410 at kernel/workqueue.c:2637
check_flush_dependency+0x10a/0x120
Workqueue: nvme-delete-wq nvme_delete_ctrl_work [nvme_core]
RIP: 0010:check_flush_dependency+0x10a/0x120[ 453.262125] Call Trace:
__flush_work.isra.0+0xbf/0x220
? __queue_work+0x1dc/0x420
flush_all_cpus_locked+0xfb/0x120
__kmem_cache_shutdown+0x2b/0x320
kmem_cache_destroy+0x49/0x100
bioset_exit+0x143/0x190
blk_release_queue+0xb9/0x100
kobject_cleanup+0x37/0x130
nvme_fc_ctrl_free+0xc6/0x150 [nvme_fc]
nvme_free_ctrl+0x1ac/0x2b0 [nvme_core]
Fix this bug by creating a workqueue for the flush operation with
the WQ_MEM_RECLAIM bit set.
Fixes: 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context")
Cc: <stable@vger.kernel.org>
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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When doing slub_debug test, kfence's 'test_memcache_typesafe_by_rcu'
kunit test case cause a use-after-free error:
BUG: KASAN: use-after-free in kobject_del+0x14/0x30
Read of size 8 at addr ffff888007679090 by task kunit_try_catch/261
CPU: 1 PID: 261 Comm: kunit_try_catch Tainted: G B N 6.0.0-rc5-next-20220916 #17
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x48
print_address_description.constprop.0+0x87/0x2a5
print_report+0x103/0x1ed
kasan_report+0xb7/0x140
kobject_del+0x14/0x30
kmem_cache_destroy+0x130/0x170
test_exit+0x1a/0x30
kunit_try_run_case+0xad/0xc0
kunit_generic_run_threadfn_adapter+0x26/0x50
kthread+0x17b/0x1b0
</TASK>
The cause is inside kmem_cache_destroy():
kmem_cache_destroy
acquire lock/mutex
shutdown_cache
schedule_work(kmem_cache_release) (if RCU flag set)
release lock/mutex
kmem_cache_release (if RCU flag not set)
In some certain timing, the scheduled work could be run before
the next RCU flag checking, which can then get a wrong value
and lead to double kmem_cache_release().
Fix it by caching the RCU flag inside protected area, just like 'refcnt'
Fixes: 0495e337b703 ("mm/slab_common: Deleting kobject in kmem_cache_destroy() without holding slab_mutex/cpu_hotplug_lock")
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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We were failing to call kasan_malloc() from __kmalloc_*track_caller()
which was causing us to sometimes fail to produce KASAN error reports
for allocations made using e.g. devm_kcalloc(), as the KASAN poison was
not being initialized. Fix it.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Cc: <stable@vger.kernel.org> # 5.15
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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Smatch checker complains that 'secretmem_mnt' dereferencing possible
ERR_PTR(). Let the function return if 'secretmem_mnt' is ERR_PTR, to
avoid deferencing it.
Link: https://lkml.kernel.org/r/20220904074647.GA64291@cloud-MacBookPro
Fixes: 1507f51255c9f ("mm: introduce memfd_secret system call to create "secret" memory areas")
Signed-off-by: Binyi Han <dantengknight@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foudation.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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These two predicates are the same for file pages, but are not the same for
anonymous pages.
Link: https://lkml.kernel.org/r/20220902192639.1737108-3-willy@infradead.org
Fixes: 07f67a8dedc0 ("mm/vmscan: convert shrink_active_list() to use a folio")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Folio fixes for 6.0".
This patch (of 2):
The recent folio conversion changed the VM_BUG_ON() to dump the folio
we're storing instead of the entry we retrieved. This was a mistake;
the entry we retrieved is the more interesting page to dump.
Link: https://lkml.kernel.org/r/20220902192639.1737108-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20220902192639.1737108-2-willy@infradead.org
Fixes: ceff9d3354e9 ("mm/swap: convert __delete_from_swap_cache() to a folio")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. Fix this up by properly calling
dput().
Link: https://lkml.kernel.org/r/20220902191149.112434-1-sj@kernel.org
Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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migrate_vma_setup() has a fast path in migrate_vma_collect_pmd() that
installs migration entries directly if it can lock the migrating page.
When removing a dirty pte the dirty bit is supposed to be carried over to
the underlying page to prevent it being lost.
Currently migrate_vma_*() can only be used for private anonymous mappings.
That means loss of the dirty bit usually doesn't result in data loss
because these pages are typically not file-backed. However pages may be
backed by swap storage which can result in data loss if an attempt is made
to migrate a dirty page that doesn't yet have the PageDirty flag set.
In this case migration will fail due to unexpected references but the
dirty pte bit will be lost. If the page is subsequently reclaimed data
won't be written back to swap storage as it is considered uptodate,
resulting in data loss if the page is subsequently accessed.
Prevent this by copying the dirty bit to the page when removing the pte to
match what try_to_migrate_one() does.
Link: https://lkml.kernel.org/r/dd48e4882ce859c295c1a77612f66d198b0403f9.1662078528.git-series.apopple@nvidia.com
Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reported-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently we only call flush_cache_page() for the anon_exclusive case,
however in both cases we clear the pte so should flush the cache.
Link: https://lkml.kernel.org/r/5676f30436ab71d1a587ac73f835ed8bd2113ff5.1662078528.git-series.apopple@nvidia.com
Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When clearing a PTE the TLB should be flushed whilst still holding the PTL
to avoid a potential race with madvise/munmap/etc. For example consider
the following sequence:
CPU0 CPU1
---- ----
migrate_vma_collect_pmd()
pte_unmap_unlock()
madvise(MADV_DONTNEED)
-> zap_pte_range()
pte_offset_map_lock()
[ PTE not present, TLB not flushed ]
pte_unmap_unlock()
[ page is still accessible via stale TLB ]
flush_tlb_range()
In this case the page may still be accessed via the stale TLB entry after
madvise returns. Fix this by flushing the TLB while holding the PTL.
Fixes: 8c3328f1f36a ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Link: https://lkml.kernel.org/r/9f801e9d8d830408f2ca27821f606e09aa856899.1662078528.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reported-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In the case where a filesystem is polled to take over the memory failure
and receives -EOPNOTSUPP it indicates that page->index and page->mapping
are valid for reverse mapping the failure address. Introduce
FSDAX_INVALID_PGOFF to distinguish when add_to_kill() is being called from
mf_dax_kill_procs() by a filesytem vs the typical memory_failure() path.
Otherwise, vma_pgoff_address() is called with an invalid fsdax_pgoff which
then trips this failing signature:
kernel BUG at mm/memory-failure.c:319!
invalid opcode: 0000 [#1] PREEMPT SMP PTI
CPU: 13 PID: 1262 Comm: dax-pmd Tainted: G OE N 6.0.0-rc2+ #62
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:add_to_kill.cold+0x19d/0x209
[..]
Call Trace:
<TASK>
collect_procs.part.0+0x2c4/0x460
memory_failure+0x71b/0xba0
? _printk+0x58/0x73
do_madvise.part.0.cold+0xaf/0xc5
Link: https://lkml.kernel.org/r/166153429427.2758201.14605968329933175594.stgit@dwillia2-xfh.jf.intel.com
Fixes: c36e20249571 ("mm: introduce mf_dax_kill_procs() for fsdax case")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Some pagemap types, like MEMORY_DEVICE_GENERIC (device-dax) do not even
have pagemap ops which results in crash signatures like this:
BUG: kernel NULL pointer dereference, address: 0000000000000010
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 8000000205073067 P4D 8000000205073067 PUD 2062b3067 PMD 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 22 PID: 4535 Comm: device-dax Tainted: G OE N 6.0.0-rc2+ #59
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:memory_failure+0x667/0xba0
[..]
Call Trace:
<TASK>
? _printk+0x58/0x73
do_madvise.part.0.cold+0xaf/0xc5
Check for ops before checking if the ops have a memory_failure()
handler.
Link: https://lkml.kernel.org/r/166153428781.2758201.1990616683438224741.stgit@dwillia2-xfh.jf.intel.com
Fixes: 33a8f7f2b3a3 ("pagemap,pmem: introduce ->memory_failure()")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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allocation
Patrick Daly reported the following problem;
NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK] - before offline operation
[0] - ZONE_MOVABLE
[1] - ZONE_NORMAL
[2] - NULL
For a GFP_KERNEL allocation, alloc_pages_slowpath() will save the
offset of ZONE_NORMAL in ac->preferred_zoneref. If a concurrent
memory_offline operation removes the last page from ZONE_MOVABLE,
build_all_zonelists() & build_zonerefs_node() will update
node_zonelists as shown below. Only populated zones are added.
NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK] - after offline operation
[0] - ZONE_NORMAL
[1] - NULL
[2] - NULL
The race is simple -- page allocation could be in progress when a memory
hot-remove operation triggers a zonelist rebuild that removes zones. The
allocation request will still have a valid ac->preferred_zoneref that is
now pointing to NULL and triggers an OOM kill.
This problem probably always existed but may be slightly easier to trigger
due to 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones
with pages managed by the buddy allocator") which distinguishes between
zones that are completely unpopulated versus zones that have valid pages
not managed by the buddy allocator (e.g. reserved, memblock, ballooning
etc). Memory hotplug had multiple stages with timing considerations
around managed/present page updates, the zonelist rebuild and the zone
span updates. As David Hildenbrand puts it
memory offlining adjusts managed+present pages of the zone
essentially in one go. If after the adjustments, the zone is no
longer populated (present==0), we rebuild the zone lists.
Once that's done, we try shrinking the zone (start+spanned
pages) -- which results in zone_start_pfn == 0 if there are no
more pages. That happens *after* rebuilding the zonelists via
remove_pfn_range_from_zone().
The only requirement to fix the race is that a page allocation request
identifies when a zonelist rebuild has happened since the allocation
request started and no page has yet been allocated. Use a seqlock_t to
track zonelist updates with a lockless read-side of the zonelist and
protecting the rebuild and update of the counter with a spinlock.
[akpm@linux-foundation.org: make zonelist_update_seq static]
Link: https://lkml.kernel.org/r/20220824110900.vh674ltxmzb3proq@techsingularity.net
Fixes: 6aa303defb74 ("mm, vmscan: only allocate and reclaim from zones with pages managed by the buddy allocator")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Patrick Daly <quic_pdaly@quicinc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org> [4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In create_unique_id(), kmalloc(, GFP_KERNEL) can fail due to
out-of-memory, if it fails, return errno correctly rather than
triggering panic via BUG_ON();
kernel BUG at mm/slub.c:5893!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Call trace:
sysfs_slab_add+0x258/0x260 mm/slub.c:5973
__kmem_cache_create+0x60/0x118 mm/slub.c:4899
create_cache mm/slab_common.c:229 [inline]
kmem_cache_create_usercopy+0x19c/0x31c mm/slab_common.c:335
kmem_cache_create+0x1c/0x28 mm/slab_common.c:390
f2fs_kmem_cache_create fs/f2fs/f2fs.h:2766 [inline]
f2fs_init_xattr_caches+0x78/0xb4 fs/f2fs/xattr.c:808
f2fs_fill_super+0x1050/0x1e0c fs/f2fs/super.c:4149
mount_bdev+0x1b8/0x210 fs/super.c:1400
f2fs_mount+0x44/0x58 fs/f2fs/super.c:4512
legacy_get_tree+0x30/0x74 fs/fs_context.c:610
vfs_get_tree+0x40/0x140 fs/super.c:1530
do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
path_mount+0x358/0x914 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x2f8/0x408 fs/namespace.c:3568
Cc: <stable@kernel.org>
Fixes: 81819f0fc8285 ("SLUB core")
Reported-by: syzbot+81684812ea68216e08c5@syzkaller.appspotmail.com
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Chao Yu <chao.yu@oppo.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
|
|
The mmap lock protects the page walker from changes to the page tables
during the walk. However a read lock is insufficient to protect those
areas which don't have a VMA as munmap() detaches the VMAs before
downgrading to a read lock and actually tearing down PTEs/page tables.
For users of walk_page_range() the solution is to simply call pte_hole()
immediately without checking the actual page tables when a VMA is not
present. We now never call __walk_page_range() without a valid vma.
For walk_page_range_novma() the locking requirements are tightened to
require the mmap write lock to be taken, and then walking the pgd
directly with 'no_vma' set.
This in turn means that all page walkers either have a valid vma, or
it's that special 'novma' case for page table debugging. As a result,
all the odd '(!walk->vma && !walk->no_vma)' tests can be removed.
Fixes: dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab fix from Vlastimil Babka:
- A fix from Waiman Long to avoid a theoretical deadlock reported by
lockdep.
* tag 'slab-for-6.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm/slab_common: Deleting kobject in kmem_cache_destroy() without holding slab_mutex/cpu_hotplug_lock
|
|
slab_mutex/cpu_hotplug_lock
A circular locking problem is reported by lockdep due to the following
circular locking dependency.
+--> cpu_hotplug_lock --> slab_mutex --> kn->active --+
| |
+-----------------------------------------------------+
The forward cpu_hotplug_lock ==> slab_mutex ==> kn->active dependency
happens in
kmem_cache_destroy(): cpus_read_lock(); mutex_lock(&slab_mutex);
==> sysfs_slab_unlink()
==> kobject_del()
==> kernfs_remove()
==> __kernfs_remove()
==> kernfs_drain(): rwsem_acquire(&kn->dep_map, ...);
The backward kn->active ==> cpu_hotplug_lock dependency happens in
kernfs_fop_write_iter(): kernfs_get_active();
==> slab_attr_store()
==> cpu_partial_store()
==> flush_all(): cpus_read_lock()
One way to break this circular locking chain is to avoid holding
cpu_hotplug_lock and slab_mutex while deleting the kobject in
sysfs_slab_unlink() which should be equivalent to doing a write_lock
and write_unlock pair of the kn->active virtual lock.
Since the kobject structures are not protected by slab_mutex or the
cpu_hotplug_lock, we can certainly release those locks before doing
the delete operation.
Move sysfs_slab_unlink() and sysfs_slab_release() to the newly
created kmem_cache_release() and call it outside the slab_mutex &
cpu_hotplug_lock critical sections. There will be a slight delay
in the deletion of sysfs files if kmem_cache_release() is called
indirectly from a work function.
Fixes: 5a836bf6b09f ("mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: David Rientjes <rientjes@google.com>
Link: https://lore.kernel.org/all/YwOImVd+nRUsSAga@hyeyoo/
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
|
|
anon_vma->degree tracks the combined number of child anon_vmas and VMAs
that use the anon_vma as their ->anon_vma.
anon_vma_clone() then assumes that for any anon_vma attached to
src->anon_vma_chain other than src->anon_vma, it is impossible for it to
be a leaf node of the VMA tree, meaning that for such VMAs ->degree is
elevated by 1 because of a child anon_vma, meaning that if ->degree
equals 1 there are no VMAs that use the anon_vma as their ->anon_vma.
This assumption is wrong because the ->degree optimization leads to leaf
nodes being abandoned on anon_vma_clone() - an existing anon_vma is
reused and no new parent-child relationship is created. So it is
possible to reuse an anon_vma for one VMA while it is still tied to
another VMA.
This is an issue because is_mergeable_anon_vma() and its callers assume
that if two VMAs have the same ->anon_vma, the list of anon_vmas
attached to the VMAs is guaranteed to be the same. When this assumption
is violated, vma_merge() can merge pages into a VMA that is not attached
to the corresponding anon_vma, leading to dangling page->mapping
pointers that will be dereferenced during rmap walks.
Fix it by separately tracking the number of child anon_vmas and the
number of VMAs using the anon_vma as their ->anon_vma.
Fixes: 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy")
Cc: stable@kernel.org
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Yu Zhao reported a bug after the commit "mm/swap: Add swp_offset_pfn() to
fetch PFN from swap entry" added a check in swp_offset_pfn() for swap type [1]:
kernel BUG at include/linux/swapops.h:117!
CPU: 46 PID: 5245 Comm: EventManager_De Tainted: G S O L 6.0.0-dbg-DEV #2
RIP: 0010:pfn_swap_entry_to_page+0x72/0xf0
Code: c6 48 8b 36 48 83 fe ff 74 53 48 01 d1 48 83 c1 08 48 8b 09 f6
c1 01 75 7b 66 90 48 89 c1 48 8b 09 f6 c1 01 74 74 5d c3 eb 9e <0f> 0b
48 ba ff ff ff ff 03 00 00 00 eb ae a9 ff 0f 00 00 75 13 48
RSP: 0018:ffffa59e73fabb80 EFLAGS: 00010282
RAX: 00000000ffffffe8 RBX: 0c00000000000000 RCX: ffffcd5440000000
RDX: 1ffffffffff7a80a RSI: 0000000000000000 RDI: 0c0000000000042b
RBP: ffffa59e73fabb80 R08: ffff9965ca6e8bb8 R09: 0000000000000000
R10: ffffffffa5a2f62d R11: 0000030b372e9fff R12: ffff997b79db5738
R13: 000000000000042b R14: 0c0000000000042b R15: 1ffffffffff7a80a
FS: 00007f549d1bb700(0000) GS:ffff99d3cf680000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000440d035b3180 CR3: 0000002243176004 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
change_pte_range+0x36e/0x880
change_p4d_range+0x2e8/0x670
change_protection_range+0x14e/0x2c0
mprotect_fixup+0x1ee/0x330
do_mprotect_pkey+0x34c/0x440
__x64_sys_mprotect+0x1d/0x30
It triggers because pfn_swap_entry_to_page() could be called upon e.g. a
genuine swap entry.
Fix it by only calling it when it's a write migration entry where the page*
is used.
[1] https://lore.kernel.org/lkml/CAOUHufaVC2Za-p8m0aiHw6YkheDcrO-C3wRGixwDS32VTS+k1w@mail.gmail.com/
Link: https://lkml.kernel.org/r/20220823221138.45602-1-peterx@redhat.com
Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Yu Zhao <yuzhao@google.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When user tries to create a DAMON context via the DAMON debugfs interface
with a name of an already existing context, the context directory creation
fails but a new context is created and added in the internal data
structure, due to absence of the directory creation success check. As a
result, memory could leak and DAMON cannot be turned on. An example test
case is as below:
# cd /sys/kernel/debug/damon/
# echo "off" > monitor_on
# echo paddr > target_ids
# echo "abc" > mk_context
# echo "abc" > mk_context
# echo $$ > abc/target_ids
# echo "on" > monitor_on <<< fails
Return value of 'debugfs_create_dir()' is expected to be ignored in
general, but this is an exceptional case as DAMON feature is depending
on the debugfs functionality and it has the potential duplicate name
issue. This commit therefore fixes the issue by checking the directory
creation failure and immediately return the error in the case.
Link: https://lkml.kernel.org/r/20220821180853.2400-1-sj@kernel.org
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: Badari Pulavarty <badari.pulavarty@intel.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [ 5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The vmemmap pages is marked by kmemleak when allocated from memblock.
Remove it from kmemleak when freeing the page. Otherwise, when we reuse
the page, kmemleak may report such an error and then stop working.
kmemleak: Cannot insert 0xffff98fb6eab3d40 into the object search tree (overlaps existing)
kmemleak: Kernel memory leak detector disabled
kmemleak: Object 0xffff98fb6be00000 (size 335544320):
kmemleak: comm "swapper", pid 0, jiffies 4294892296
kmemleak: min_count = 0
kmemleak: count = 0
kmemleak: flags = 0x1
kmemleak: checksum = 0
kmemleak: backtrace:
Link: https://lkml.kernel.org/r/20220819094005.2928241-1-liushixin2@huawei.com
Fixes: f41f2ed43ca5 (mm: hugetlb: free the vmemmap pages associated with each HugeTLB page)
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
zsmalloc() now returns ERR_PTR values as handles, which zram accidentally
can pass to zs_free(). Another bad scenario is when zcomp_compress()
fails - handle has default -ENOMEM value, and zs_free() will try to free
that "pointer value".
Add the missing check and make sure that zs_free() bails out when
ERR_PTR() is passed to it.
Link: https://lkml.kernel.org/r/20220816050906.2583956-1-senozhatsky@chromium.org
Fixes: c7e6f17b52e9 ("zsmalloc: zs_malloc: return ERR_PTR on failure")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>,
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When a disk is removed, bdi_unregister gets called to stop further
writeback and wait for associated delayed work to complete. However,
wb_inode_writeback_end() may schedule bandwidth estimation dwork after
this has completed, which can result in the timer attempting to access the
just freed bdi_writeback.
Fix this by checking if the bdi_writeback is alive, similar to when
scheduling writeback work.
Since this requires wb->work_lock, and wb_inode_writeback_end() may get
called from interrupt, switch wb->work_lock to an irqsafe lock.
Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com
Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload")
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Michael Stapelberg <stapelberg+linux@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
If we allocate a new page, we need to make sure that our folio matches
that new page.
If we do end up in this code path, we store the wrong page in the shmem
inode's page cache, and I would rather imagine that data corruption
ensues.
This will be solved by changing shmem_replace_page() to
shmem_replace_folio(), but this is the minimal fix.
Link: https://lkml.kernel.org/r/20220730042518.1264767-1-willy@infradead.org
Fixes: da08e9b79323 ("mm/shmem: convert shmem_swapin_page() to shmem_swapin_folio()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
In MCOPY_ATOMIC_CONTINUE case with a non-shared VMA, pages in the page
cache are installed in the ptes. But hugepage_add_new_anon_rmap is called
for them mistakenly because they're not vm_shared. This will corrupt the
page->mapping used by page cache code.
Link: https://lkml.kernel.org/r/20220712130542.18836-1-linmiaohe@huawei.com
Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Elsewhere, NR_SHMEM is updated at the same time as shmem NR_FILE_PAGES;
but shmem_replace_page() was forgetting to do that - so NR_SHMEM stats
could grow too big or too small, in those unusual cases when it's used.
Link: https://lkml.kernel.org/r/cec7c09d-5874-e160-ada6-6e10ee48784@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Radoslaw Burny <rburny@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
5.18 fixed the btrfs and ext4 fallocates to use file_modified(), as xfs
was already doing, to drop privileges: and fstests generic/{683,684,688}
expect this. There's no need to argue over keep-size allocation (which
could just update ctime): fix shmem_fallocate() to behave the same way.
Link: https://lkml.kernel.org/r/39c5e62-4896-7795-c0a0-f79c50d4909@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Radoslaw Burny <rburny@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
ext[234] have always allowed unimplemented chattr flags to be set, but
other filesystems have tended to be stricter. Follow the stricter
approach for tmpfs: I don't want to have to explain why csu attributes
don't actually work, and we won't need to update the chattr(1) manpage;
and it's never wrong to start off strict, relaxing later if persuaded.
Allow only a (append only) i (immutable) A (no atime) and d (no dump).
Although lsattr showed 'A' inherited, the NOATIME behavior was not being
inherited: because nothing sync'ed FS_NOATIME_FL to S_NOATIME. Add
shmem_set_inode_flags() to sync the flags, using inode_set_flags() to
avoid that instant of lost immutablility during fileattr_set().
But that change switched generic/079 from passing to failing: because
FS_IMMUTABLE_FL and FS_APPEND_FL had been unconventionally included in the
INHERITED fsflags: remove them and generic/079 is back to passing.
Link: https://lkml.kernel.org/r/2961dcb0-ddf3-b9f0-3268-12a4ff996856@google.com
Fixes: e408e695f5f1 ("mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Radoslaw Burny <rburny@google.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
If we ever get a write-fault on a write-protected page in a shared
mapping, we'd be in trouble (again). Instead, we can simply map the page
writable.
And in fact, there is even a way right now to trigger that code via
uffd-wp ever since we stared to support it for shmem in 5.19:
--------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/ioctl.h>
#include <linux/userfaultfd.h>
#define HUGETLB_SIZE (2 * 1024 * 1024u)
static char *map;
int uffd;
static int temp_setup_uffd(void)
{
struct uffdio_api uffdio_api;
struct uffdio_register uffdio_register;
struct uffdio_writeprotect uffd_writeprotect;
struct uffdio_range uffd_range;
uffd = syscall(__NR_userfaultfd,
O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY);
if (uffd < 0) {
fprintf(stderr, "syscall() failed: %d\n", errno);
return -errno;
}
uffdio_api.api = UFFD_API;
uffdio_api.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP;
if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) {
fprintf(stderr, "UFFDIO_API failed: %d\n", errno);
return -errno;
}
if (!(uffdio_api.features & UFFD_FEATURE_PAGEFAULT_FLAG_WP)) {
fprintf(stderr, "UFFD_FEATURE_WRITEPROTECT missing\n");
return -ENOSYS;
}
/* Register UFFD-WP */
uffdio_register.range.start = (unsigned long) map;
uffdio_register.range.len = HUGETLB_SIZE;
uffdio_register.mode = UFFDIO_REGISTER_MODE_WP;
if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) < 0) {
fprintf(stderr, "UFFDIO_REGISTER failed: %d\n", errno);
return -errno;
}
/* Writeprotect a single page. */
uffd_writeprotect.range.start = (unsigned long) map;
uffd_writeprotect.range.len = HUGETLB_SIZE;
uffd_writeprotect.mode = UFFDIO_WRITEPROTECT_MODE_WP;
if (ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect)) {
fprintf(stderr, "UFFDIO_WRITEPROTECT failed: %d\n", errno);
return -errno;
}
/* Unregister UFFD-WP without prior writeunprotection. */
uffd_range.start = (unsigned long) map;
uffd_range.len = HUGETLB_SIZE;
if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_range)) {
fprintf(stderr, "UFFDIO_UNREGISTER failed: %d\n", errno);
return -errno;
}
return 0;
}
int main(int argc, char **argv)
{
int fd;
fd = open("/dev/hugepages/tmp", O_RDWR | O_CREAT);
if (!fd) {
fprintf(stderr, "open() failed\n");
return -errno;
}
if (ftruncate(fd, HUGETLB_SIZE)) {
fprintf(stderr, "ftruncate() failed\n");
return -errno;
}
map = mmap(NULL, HUGETLB_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (map == MAP_FAILED) {
fprintf(stderr, "mmap() failed\n");
return -errno;
}
*map = 0;
if (temp_setup_uffd())
return 1;
*map = 0;
return 0;
}
--------------------------------------------------------------------------
Above test fails with SIGBUS when there is only a single free hugetlb page.
# echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
# ./test
Bus error (core dumped)
And worse, with sufficient free hugetlb pages it will map an anonymous page
into a shared mapping, for example, messing up accounting during unmap
and breaking MAP_SHARED semantics:
# echo 2 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
# ./test
# cat /proc/meminfo | grep HugePages_
HugePages_Total: 2
HugePages_Free: 1
HugePages_Rsvd: 18446744073709551615
HugePages_Surp: 0
Reason is that uffd-wp doesn't clear the uffd-wp PTE bit when
unregistering and consequently keeps the PTE writeprotected. Reason for
this is to avoid the additional overhead when unregistering. Note that
this is the case also for !hugetlb and that we will end up with writable
PTEs that still have the uffd-wp PTE bit set once we return from
hugetlb_wp(). I'm not touching the uffd-wp PTE bit for now, because it
seems to be a generic thing -- wp_page_reuse() also doesn't clear it.
VM_MAYSHARE handling in hugetlb_fault() for FAULT_FLAG_WRITE indicates
that MAP_SHARED handling was at least envisioned, but could never have
worked as expected.
While at it, make sure that we never end up in hugetlb_wp() on write
faults without VM_WRITE, because we don't support maybe_mkwrite()
semantics as commonly used in the !hugetlb case -- for example, in
wp_page_reuse().
Note that there is no need to do any kind of reservation in
hugetlb_fault() in this case ... because we already have a hugetlb page
mapped R/O that we will simply map writable and we are not dealing with
COW/unsharing.
Link: https://lkml.kernel.org/r/20220811103435.188481-3-david@redhat.com
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org> [5.19]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/hugetlb: fix write-fault handling for shared mappings", v2.
I observed that hugetlb does not support/expect write-faults in shared
mappings that would have to map the R/O-mapped page writable -- and I
found two case where we could currently get such faults and would
erroneously map an anon page into a shared mapping.
Reproducers part of the patches.
I propose to backport both fixes to stable trees. The first fix needs a
small adjustment.
This patch (of 2):
Staring at hugetlb_wp(), one might wonder where all the logic for shared
mappings is when stumbling over a write-protected page in a shared
mapping. In fact, there is none, and so far we thought we could get away
with that because e.g., mprotect() should always do the right thing and
map all pages directly writable.
Looks like we were wrong:
--------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#define HUGETLB_SIZE (2 * 1024 * 1024u)
static void clear_softdirty(void)
{
int fd = open("/proc/self/clear_refs", O_WRONLY);
const char *ctrl = "4";
int ret;
if (fd < 0) {
fprintf(stderr, "open(clear_refs) failed\n");
exit(1);
}
ret = write(fd, ctrl, strlen(ctrl));
if (ret != strlen(ctrl)) {
fprintf(stderr, "write(clear_refs) failed\n");
exit(1);
}
close(fd);
}
int main(int argc, char **argv)
{
char *map;
int fd;
fd = open("/dev/hugepages/tmp", O_RDWR | O_CREAT);
if (!fd) {
fprintf(stderr, "open() failed\n");
return -errno;
}
if (ftruncate(fd, HUGETLB_SIZE)) {
fprintf(stderr, "ftruncate() failed\n");
return -errno;
}
map = mmap(NULL, HUGETLB_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (map == MAP_FAILED) {
fprintf(stderr, "mmap() failed\n");
return -errno;
}
*map = 0;
if (mprotect(map, HUGETLB_SIZE, PROT_READ)) {
fprintf(stderr, "mmprotect() failed\n");
return -errno;
}
clear_softdirty();
if (mprotect(map, HUGETLB_SIZE, PROT_READ|PROT_WRITE)) {
fprintf(stderr, "mmprotect() failed\n");
return -errno;
}
*map = 0;
return 0;
}
--------------------------------------------------------------------------
Above test fails with SIGBUS when there is only a single free hugetlb page.
# echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
# ./test
Bus error (core dumped)
And worse, with sufficient free hugetlb pages it will map an anonymous page
into a shared mapping, for example, messing up accounting during unmap
and breaking MAP_SHARED semantics:
# echo 2 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
# ./test
# cat /proc/meminfo | grep HugePages_
HugePages_Total: 2
HugePages_Free: 1
HugePages_Rsvd: 18446744073709551615
HugePages_Surp: 0
Reason in this particular case is that vma_wants_writenotify() will
return "true", removing VM_SHARED in vma_set_page_prot() to map pages
write-protected. Let's teach vma_wants_writenotify() that hugetlb does not
support softdirty tracking.
Link: https://lkml.kernel.org/r/20220811103435.188481-1-david@redhat.com
Link: https://lkml.kernel.org/r/20220811103435.188481-2-david@redhat.com
Fixes: 64e455079e1b ("mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org> [3.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The motivation of this patch comes from a recent report and patchfix from
David Hildenbrand on hugetlb shared handling of wr-protected page [1].
With the reproducer provided in commit message of [1], one can leverage
the uffd-wp lazy-reset of ptes to trigger a hugetlb issue which can affect
not only the attacker process, but also the whole system.
The lazy-reset mechanism of uffd-wp was used to make unregister faster,
meanwhile it has an assumption that any leftover pgtable entries should
only affect the process on its own, so not only the user should be aware
of anything it does, but also it should not affect outside of the process.
But it seems that this is not true, and it can also be utilized to make
some exploit easier.
So far there's no clue showing that the lazy-reset is important to any
userfaultfd users because normally the unregister will only happen once
for a specific range of memory of the lifecycle of the process.
Considering all above, what this patch proposes is to do explicit pte
resets when unregister an uffd region with wr-protect mode enabled.
It should be the same as calling ioctl(UFFDIO_WRITEPROTECT, wp=false)
right before ioctl(UFFDIO_UNREGISTER) for the user. So potentially it'll
make the unregister slower. From that pov it's a very slight abi change,
but hopefully nothing should break with this change either.
Regarding to the change itself - core of uffd write [un]protect operation
is moved into a separate function (uffd_wp_range()) and it is reused in
the unregister code path.
Note that the new function will not check for anything, e.g. ranges or
memory types, because they should have been checked during the previous
UFFDIO_REGISTER or it should have failed already. It also doesn't check
mmap_changing because we're with mmap write lock held anyway.
I added a Fixes upon introducing of uffd-wp shmem+hugetlbfs because that's
the only issue reported so far and that's the commit David's reproducer
will start working (v5.19+). But the whole idea actually applies to not
only file memories but also anonymous. It's just that we don't need to
fix anonymous prior to v5.19- because there's no known way to exploit.
IOW, this patch can also fix the issue reported in [1] as the patch 2 does.
[1] https://lore.kernel.org/all/20220811103435.188481-3-david@redhat.com/
Link: https://lkml.kernel.org/r/20220811201340.39342-1-peterx@redhat.com
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
FOR_ALL_ZONES should be consistent with enum zone_type. Otherwise,
__count_zid_vm_events have the potential to add count to wrong item when
zid is ZONE_DEVICE.
Link: https://lkml.kernel.org/r/20220807154442.GA18167@haolee.io
Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Ever since the Dirty COW (CVE-2016-5195) security issue happened, we know
that FOLL_FORCE can be possibly dangerous, especially if there are races
that can be exploited by user space.
Right now, it would be sufficient to have some code that sets a PTE of a
R/O-mapped shared page dirty, in order for it to erroneously become
writable by FOLL_FORCE. The implications of setting a write-protected PTE
dirty might not be immediately obvious to everyone.
And in fact ever since commit 9ae0f87d009c ("mm/shmem: unconditionally set
pte dirty in mfill_atomic_install_pte"), we can use UFFDIO_CONTINUE to map
a shmem page R/O while marking the pte dirty. This can be used by
unprivileged user space to modify tmpfs/shmem file content even if the
user does not have write permissions to the file, and to bypass memfd
write sealing -- Dirty COW restricted to tmpfs/shmem (CVE-2022-2590).
To fix such security issues for good, the insight is that we really only
need that fancy retry logic (FOLL_COW) for COW mappings that are not
writable (!VM_WRITE). And in a COW mapping, we really only broke COW if
we have an exclusive anonymous page mapped. If we have something else
mapped, or the mapped anonymous page might be shared (!PageAnonExclusive),
we have to trigger a write fault to break COW. If we don't find an
exclusive anonymous page when we retry, we have to trigger COW breaking
once again because something intervened.
Let's move away from this mandatory-retry + dirty handling and rely on our
PageAnonExclusive() flag for making a similar decision, to use the same
COW logic as in other kernel parts here as well. In case we stumble over
a PTE in a COW mapping that does not map an exclusive anonymous page, COW
was not properly broken and we have to trigger a fake write-fault to break
COW.
Just like we do in can_change_pte_writable() added via commit 64fe24a3e05e
("mm/mprotect: try avoiding write faults for exclusive anonymous pages
when changing protection") and commit 76aefad628aa ("mm/mprotect: fix
soft-dirty check in can_change_pte_writable()"), take care of softdirty
and uffd-wp manually.
For example, a write() via /proc/self/mem to a uffd-wp-protected range has
to fail instead of silently granting write access and bypassing the
userspace fault handler. Note that FOLL_FORCE is not only used for debug
access, but also triggered by applications without debug intentions, for
example, when pinning pages via RDMA.
This fixes CVE-2022-2590. Note that only x86_64 and aarch64 are
affected, because only those support CONFIG_HAVE_ARCH_USERFAULTFD_MINOR.
Fortunately, FOLL_COW is no longer required to handle FOLL_FORCE. So
let's just get rid of it.
Thanks to Nadav Amit for pointing out that the pte_dirty() check in
FOLL_FORCE code is problematic and might be exploitable.
Note 1: We don't check for the PTE being dirty because it doesn't matter
for making a "was COWed" decision anymore, and whoever modifies the
page has to set the page dirty either way.
Note 2: Kernels before extended uffd-wp support and before
PageAnonExclusive (< 5.19) can simply revert the problematic
commit instead and be safe regarding UFFDIO_CONTINUE. A backport to
v5.19 requires minor adjustments due to lack of
vma_soft_dirty_enabled().
Link: https://lkml.kernel.org/r/20220809205640.70916-1-david@redhat.com
Fixes: 9ae0f87d009c ("mm/shmem: unconditionally set pte dirty in mfill_atomic_install_pte")
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: <stable@vger.kernel.org> [5.16]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull remaining MM updates from Andrew Morton:
"Three patch series - two that perform cleanups and one feature:
- hugetlb_vmemmap cleanups from Muchun Song
- hardware poisoning support for 1GB hugepages, from Naoya Horiguchi
- highmem documentation fixups from Fabio De Francesco"
* tag 'mm-stable-2022-08-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (23 commits)
Documentation/mm: add details about kmap_local_page() and preemption
highmem: delete a sentence from kmap_local_page() kdocs
Documentation/mm: rrefer kmap_local_page() and avoid kmap()
Documentation/mm: avoid invalid use of addresses from kmap_local_page()
Documentation/mm: don't kmap*() pages which can't come from HIGHMEM
highmem: specify that kmap_local_page() is callable from interrupts
highmem: remove unneeded spaces in kmap_local_page() kdocs
mm, hwpoison: enable memory error handling on 1GB hugepage
mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage
mm, hwpoison: make __page_handle_poison returns int
mm, hwpoison: set PG_hwpoison for busy hugetlb pages
mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage
mm, hwpoison, hugetlb: support saving mechanism of raw error pages
mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry
mm/hugetlb: check gigantic_page_runtime_supported() in return_unused_surplus_pages()
mm: hugetlb_vmemmap: use PTRS_PER_PTE instead of PMD_SIZE / PAGE_SIZE
mm: hugetlb_vmemmap: move code comments to vmemmap_dedup.rst
mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability
mm: hugetlb_vmemmap: replace early_param() with core_param()
mm: hugetlb_vmemmap: move vmemmap code related to HugeTLB to hugetlb_vmemmap.c
...
|
|
Pull cxl updates from Dan Williams:
"Compute Express Link (CXL) updates for 6.0:
- Introduce a 'struct cxl_region' object with support for
provisioning and assembling persistent memory regions.
- Introduce alloc_free_mem_region() to accompany the existing
request_free_mem_region() as a method to allocate physical memory
capacity out of an existing resource.
- Export insert_resource_expand_to_fit() for the CXL subsystem to
late-publish CXL platform windows in iomem_resource.
- Add a polled mode PCI DOE (Data Object Exchange) driver service and
use it in cxl_pci to retrieve the CDAT (Coherent Device Attribute
Table)"
* tag 'cxl-for-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (74 commits)
cxl/hdm: Fix skip allocations vs multiple pmem allocations
cxl/region: Disallow region granularity != window granularity
cxl/region: Fix x1 interleave to greater than x1 interleave routing
cxl/region: Move HPA setup to cxl_region_attach()
cxl/region: Fix decoder interleave programming
Documentation: cxl: remove dangling kernel-doc reference
cxl/region: describe targets and nr_targets members of cxl_region_params
cxl/regions: add padding for cxl_rr_ep_add nested lists
cxl/region: Fix IS_ERR() vs NULL check
cxl/region: Fix region reference target accounting
cxl/region: Fix region commit uninitialized variable warning
cxl/region: Fix port setup uninitialized variable warnings
cxl/region: Stop initializing interleave granularity
cxl/hdm: Fix DPA reservation vs cxl_endpoint_decoder lifetime
cxl/acpi: Minimize granularity for x1 interleaves
cxl/region: Delete 'region' attribute from root decoders
cxl/acpi: Autoload driver for 'cxl_acpi' test devices
cxl/region: decrement ->nr_targets on error in cxl_region_attach()
cxl/region: prevent underflow in ways_to_cxl()
cxl/region: uninitialized variable in alloc_hpa()
...
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock
Pull memblock updates from Mike Rapoport:
- An optimization in memblock_add_range() to reduce array traversals
- Improvements to the memblock test suite
* tag 'memblock-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
memblock test: Modify the obsolete description in README
memblock tests: fix compilation errors
memblock tests: change build options to run-time options
memblock tests: remove completed TODO items
memblock tests: set memblock_debug to enable memblock_dbg() messages
memblock tests: add verbose output to memblock tests
memblock tests: Makefile: add arguments to control verbosity
memblock: avoid some repeat when add new range
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more iov_iter updates from Al Viro:
- more new_sync_{read,write}() speedups - ITER_UBUF introduction
- ITER_PIPE cleanups
- unification of iov_iter_get_pages/iov_iter_get_pages_alloc and
switching them to advancing semantics
- making ITER_PIPE take high-order pages without splitting them
- handling copy_page_from_iter() for high-order pages properly
* tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (32 commits)
fix copy_page_from_iter() for compound destinations
hugetlbfs: copy_page_to_iter() can deal with compound pages
copy_page_to_iter(): don't split high-order page in case of ITER_PIPE
expand those iov_iter_advance()...
pipe_get_pages(): switch to append_pipe()
get rid of non-advancing variants
ceph: switch the last caller of iov_iter_get_pages_alloc()
9p: convert to advancing variant of iov_iter_get_pages_alloc()
af_alg_make_sg(): switch to advancing variant of iov_iter_get_pages()
iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()
block: convert to advancing variants of iov_iter_get_pages{,_alloc}()
iov_iter: advancing variants of iov_iter_get_pages{,_alloc}()
iov_iter: saner helper for page array allocation
fold __pipe_get_pages() into pipe_get_pages()
ITER_XARRAY: don't open-code DIV_ROUND_UP()
unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts
unify xarray_get_pages() and xarray_get_pages_alloc()
unify pipe_get_pages() and pipe_get_pages_alloc()
iov_iter_get_pages(): sanity-check arguments
iov_iter_get_pages_alloc(): lift freeing pages array on failure exits into wrapper
...
|
|
Equivalent of single-segment iovec. Initialized by iov_iter_ubuf(),
checked for by iter_is_ubuf(), otherwise behaves like ITER_IOVEC
ones.
We are going to expose the things like ->write_iter() et.al. to those
in subsequent commits.
New predicate (user_backed_iter()) that is true for ITER_IOVEC and
ITER_UBUF; places like direct-IO handling should use that for
checking that pages we modify after getting them from iov_iter_get_pages()
would need to be dirtied.
DO NOT assume that replacing iter_is_iovec() with user_backed_iter()
will solve all problems - there's code that uses iter_is_iovec() to
decide how to poke around in iov_iter guts and for that the predicate
replacement obviously won't suffice.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
|
Now error handling code is prepared, so remove the blocking code and
enable memory error handling on 1GB hugepage.
Link: https://lkml.kernel.org/r/20220714042420.1847125-9-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently if memory_failure() (modified to remove blocking code with
subsequent patch) is called on a page in some 1GB hugepage, memory error
handling fails and the raw error page gets into leaked state. The impact
is small in production systems (just leaked single 4kB page), but this
limits the testability because unpoison doesn't work for it. We can no
longer create 1GB hugepage on the 1GB physical address range with such
leaked pages, that's not useful when testing on small systems.
When a hwpoison page in a 1GB hugepage is handled, it's caught by the
PageHWPoison check in free_pages_prepare() because the 1GB hugepage is
broken down into raw error pages before coming to this point:
if (unlikely(PageHWPoison(page)) && !order) {
...
return false;
}
Then, the page is not sent to buddy and the page refcount is left 0.
Originally this check is supposed to work when the error page is freed
from page_handle_poison() (that is called from soft-offline), but now we
are opening another path to call it, so the callers of
__page_handle_poison() need to handle the case by considering the return
value 0 as success. Then page refcount for hwpoison is properly
incremented so unpoison works.
Link: https://lkml.kernel.org/r/20220714042420.1847125-8-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
__page_handle_poison() returns bool that shows whether
take_page_off_buddy() has passed or not now. But we will want to
distinguish another case of "dissolve has passed but taking off failed" by
its return value. So change the type of the return value. No functional
change.
Link: https://lkml.kernel.org/r/20220714042420.1847125-7-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
If memory_failure() fails to grab page refcount on a hugetlb page because
it's busy, it returns without setting PG_hwpoison on it. This not only
loses a chance of error containment, but breaks the rule that
action_result() should be called only when memory_failure() do any of
handling work (even if that's just setting PG_hwpoison). This
inconsistency could harm code maintainability.
So set PG_hwpoison and call hugetlb_set_page_hwpoison() for such a case.
Link: https://lkml.kernel.org/r/20220714042420.1847125-6-naoya.horiguchi@linux.dev
Fixes: 405ce051236c ("mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Raw error info list needs to be removed when hwpoisoned hugetlb is
unpoisoned. And unpoison handler needs to know how many errors there are
in the target hugepage. So add them.
HPageVmemmapOptimized(hpage) and HPageRawHwpUnreliable(hpage)) sometimes
can't be unpoisoned, so skip them.
Link: https://lkml.kernel.org/r/20220714042420.1847125-5-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When handling memory error on a hugetlb page, the error handler tries to
dissolve and turn it into 4kB pages. If it's successfully dissolved,
PageHWPoison flag is moved to the raw error page, so that's all right.
However, dissolve sometimes fails, then the error page is left as
hwpoisoned hugepage. It's useful if we can retry to dissolve it to save
healthy pages, but that's not possible now because the information about
where the raw error pages is lost.
Use the private field of a few tail pages to keep that information. The
code path of shrinking hugepage pool uses this info to try delayed
dissolve. In order to remember multiple errors in a hugepage, a
singly-linked list originated from SUBPAGE_INDEX_HWPOISON-th tail page is
constructed. Only simple operations (adding an entry or clearing all) are
required and the list is assumed not to be very long, so this simple data
structure should be enough.
If we failed to save raw error info, the hwpoison hugepage has errors on
unknown subpage, then this new saving mechanism does not work any more, so
disable saving new raw error info and freeing hwpoison hugepages.
Link: https://lkml.kernel.org/r/20220714042420.1847125-4-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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follow_pud_mask() does not support non-present pud entry now. As long as
I tested on x86_64 server, follow_pud_mask() still simply returns
no_page_table() for non-present_pud_entry() due to pud_bad(), so no severe
user-visible effect should happen. But generally we should call
follow_huge_pud() for non-present pud entry for 1GB hugetlb page.
Update pud_huge() and follow_huge_pud() to handle non-present pud entries.
The changes are similar to previous works for pud entries commit
e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()") and
commit cbef8478bee5 ("mm/hugetlb: pmd_huge() returns true for non-present
hugepage").
Link: https://lkml.kernel.org/r/20220714042420.1847125-3-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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return_unused_surplus_pages()
Patch series "mm, hwpoison: enable 1GB hugepage support", v7.
This patch (of 8):
I found a weird state of 1GB hugepage pool, caused by the following
procedure:
- run a process reserving all free 1GB hugepages,
- shrink free 1GB hugepage pool to zero (i.e. writing 0 to
/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages), then
- kill the reserving process.
, then all the hugepages are free *and* surplus at the same time.
$ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
3
$ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages
3
$ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/resv_hugepages
0
$ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/surplus_hugepages
3
This state is resolved by reserving and allocating the pages then freeing
them again, so this seems not to result in serious problem. But it's a
little surprising (shrinking pool suddenly fails).
This behavior is caused by hstate_is_gigantic() check in
return_unused_surplus_pages(). This was introduced so long ago in 2008 by
commit aa888a74977a ("hugetlb: support larger than MAX_ORDER"), and at
that time the gigantic pages were not supposed to be allocated/freed at
run-time. Now kernel can support runtime allocation/free, so let's check
gigantic_page_runtime_supported() together.
Link: https://lkml.kernel.org/r/20220714042420.1847125-1-naoya.horiguchi@linux.dev
Link: https://lkml.kernel.org/r/20220714042420.1847125-2-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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There is already a macro PTRS_PER_PTE to represent the number of page
table entries, just use it.
Link: https://lkml.kernel.org/r/20220628092235.91270-9-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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There is a discussion about the name of hugetlb_vmemmap_alloc/free in
thread [1]. The suggestion suggested by David is rename "alloc/free" to
"optimize/restore" to make functionalities clearer to users, "optimize"
means the function will optimize vmemmap pages, while "restore" means
restoring its vmemmap pages discared before. This commit does this.
Another discussion is the confusion RESERVE_VMEMMAP_NR isn't used
explicitly for vmemmap_addr but implicitly for vmemmap_end in
hugetlb_vmemmap_alloc/free. David suggested we can compute what
hugetlb_vmemmap_init() does now at runtime. We do not need to worry for
the overhead of computing at runtime since the calculation is simple
enough and those functions are not in a hot path. This commit has the
following improvements:
1) The function suffixed name ("optimize/restore") is more expressive.
2) The logic becomes less weird in hugetlb_vmemmap_optimize/restore().
3) The hugetlb_vmemmap_init() does not need to be exported anymore.
4) A ->optimize_vmemmap_pages field in struct hstate is killed.
5) There is only one place where checks is_power_of_2(sizeof(struct
page)) instead of two places.
6) Add more comments for hugetlb_vmemmap_optimize/restore().
7) For external users, hugetlb_optimize_vmemmap_pages() is used for
detecting if the HugeTLB's vmemmap pages is optimizable originally.
In this commit, it is killed and we introduce a new helper
hugetlb_vmemmap_optimizable() to replace it. The name is more
expressive.
Link: https://lore.kernel.org/all/20220404074652.68024-2-songmuchun@bytedance.com/ [1]
Link: https://lkml.kernel.org/r/20220628092235.91270-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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