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  1. 06 3月, 2020 4 次提交
    • S
      mm/z3fold.c: do not include rwlock.h directly · a8198fed
      由 Sebastian Andrzej Siewior 提交于 
      rwlock.h should not be included directly. Instead linux/splinlock.h
should be included. One thing it does is to break the RT build.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200224133631.1510569-1-bigeasy@linutronix.deSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a8198fed
    • K
      mm: avoid data corruption on CoW fault into PFN-mapped VMA · c3e5ea6e
      由 Kirill A. Shutemov 提交于 
      Jeff Moyer has reported that one of xfstests triggers a warning when run
on DAX-enabled filesystem:

	WARNING: CPU: 76 PID: 51024 at mm/memory.c:2317 wp_page_copy+0xc40/0xd50
	...
	wp_page_copy+0x98c/0xd50 (unreliable)
	do_wp_page+0xd8/0xad0
	__handle_mm_fault+0x748/0x1b90
	handle_mm_fault+0x120/0x1f0
	__do_page_fault+0x240/0xd70
	do_page_fault+0x38/0xd0
	handle_page_fault+0x10/0x30

The warning happens on failed __copy_from_user_inatomic() which tries to
copy data into a CoW page.

This happens because of race between MADV_DONTNEED and CoW page fault:

	CPU0					CPU1
 handle_mm_fault()
   do_wp_page()
     wp_page_copy()
       do_wp_page()
					madvise(MADV_DONTNEED)
					  zap_page_range()
					    zap_pte_range()
					      ptep_get_and_clear_full()
					      <TLB flush>
	 __copy_from_user_inatomic()
	 sees empty PTE and fails
	 WARN_ON_ONCE(1)
	 clear_page()

The solution is to re-try __copy_from_user_inatomic() under PTL after
checking that PTE is matches the orig_pte.

The second copy attempt can still fail, like due to non-readable PTE, but
there's nothing reasonable we can do about, except clearing the CoW page.
Reported-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: NJeff Moyer <jmoyer@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: Justin He <Justin.He@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Link: http://lkml.kernel.org/r/20200218154151.13349-1-kirill.shutemov@linux.intel.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c3e5ea6e
    • H
      mm: fix possible PMD dirty bit lost in set_pmd_migration_entry() · 8a8683ad
      由 Huang Ying 提交于 
      In set_pmd_migration_entry(), pmdp_invalidate() is used to change PMD
atomically.  But the PMD is read before that with an ordinary memory
reading.  If the THP (transparent huge page) is written between the PMD
reading and pmdp_invalidate(), the PMD dirty bit may be lost, and cause
data corruption.  The race window is quite small, but still possible in
theory, so need to be fixed.

The race is fixed via using the return value of pmdp_invalidate() to get
the original content of PMD, which is a read/modify/write atomic
operation.  So no THP writing can occur in between.

The race has been introduced when the THP migration support is added in
the commit 616b8371 ("mm: thp: enable thp migration in generic path").
But this fix depends on the commit d52605d7 ("mm: do not lose dirty
and accessed bits in pmdp_invalidate()").  So it's easy to be backported
after v4.16.  But the race window is really small, so it may be fine not
to backport the fix at all.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: N"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: NZi Yan <ziy@nvidia.com>
Reviewed-by: NWilliam Kucharski <william.kucharski@oracle.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/r/20200220075220.2327056-1-ying.huang@intel.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8a8683ad
    • M
      mm, numa: fix bad pmd by atomically check for pmd_trans_huge when marking page tables prot_numa · 8b272b3c
      由 Mel Gorman 提交于 
      : A user reported a bug against a distribution kernel while running a
: proprietary workload described as "memory intensive that is not swapping"
: that is expected to apply to mainline kernels.  The workload is
: read/write/modifying ranges of memory and checking the contents.  They
: reported that within a few hours that a bad PMD would be reported followed
: by a memory corruption where expected data was all zeros.  A partial
: report of the bad PMD looked like
:
:   [ 5195.338482] ../mm/pgtable-generic.c:33: bad pmd ffff8888157ba008(000002e0396009e2)
:   [ 5195.341184] ------------[ cut here ]------------
:   [ 5195.356880] kernel BUG at ../mm/pgtable-generic.c:35!
:   ....
:   [ 5195.410033] Call Trace:
:   [ 5195.410471]  [<ffffffff811bc75d>] change_protection_range+0x7dd/0x930
:   [ 5195.410716]  [<ffffffff811d4be8>] change_prot_numa+0x18/0x30
:   [ 5195.410918]  [<ffffffff810adefe>] task_numa_work+0x1fe/0x310
:   [ 5195.411200]  [<ffffffff81098322>] task_work_run+0x72/0x90
:   [ 5195.411246]  [<ffffffff81077139>] exit_to_usermode_loop+0x91/0xc2
:   [ 5195.411494]  [<ffffffff81003a51>] prepare_exit_to_usermode+0x31/0x40
:   [ 5195.411739]  [<ffffffff815e56af>] retint_user+0x8/0x10
:
: Decoding revealed that the PMD was a valid prot_numa PMD and the bad PMD
: was a false detection.  The bug does not trigger if automatic NUMA
: balancing or transparent huge pages is disabled.
:
: The bug is due a race in change_pmd_range between a pmd_trans_huge and
: pmd_nond_or_clear_bad check without any locks held.  During the
: pmd_trans_huge check, a parallel protection update under lock can have
: cleared the PMD and filled it with a prot_numa entry between the transhuge
: check and the pmd_none_or_clear_bad check.
:
: While this could be fixed with heavy locking, it's only necessary to make
: a copy of the PMD on the stack during change_pmd_range and avoid races.  A
: new helper is created for this as the check if quite subtle and the
: existing similar helpful is not suitable.  This passed 154 hours of
: testing (usually triggers between 20 minutes and 24 hours) without
: detecting bad PMDs or corruption.  A basic test of an autonuma-intensive
: workload showed no significant change in behaviour.

Although Mel withdrew the patch on the face of LKML comment
https://lkml.org/lkml/2017/4/10/922 the race window aforementioned is
still open, and we have reports of Linpack test reporting bad residuals
after the bad PMD warning is observed.  In addition to that, bad
rss-counter and non-zero pgtables assertions are triggered on mm teardown
for the task hitting the bad PMD.

 host kernel: mm/pgtable-generic.c:40: bad pmd 00000000b3152f68(8000000d2d2008e7)
 ....
 host kernel: BUG: Bad rss-counter state mm:00000000b583043d idx:1 val:512
 host kernel: BUG: non-zero pgtables_bytes on freeing mm: 4096

The issue is observed on a v4.18-based distribution kernel, but the race
window is expected to be applicable to mainline kernels, as well.

[akpm@linux-foundation.org: fix comment typo, per Rafael]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NRafael Aquini <aquini@redhat.com>
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200216191800.22423-1-aquini@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8b272b3c
  3. 22 2月, 2020 4 次提交
    • W
      mm/sparsemem: pfn_to_page is not valid yet on SPARSEMEM · 18e19f19
      由 Wei Yang 提交于 
      When we use SPARSEMEM instead of SPARSEMEM_VMEMMAP, pfn_to_page()
doesn't work before sparse_init_one_section() is called.

This leads to a crash when hotplug memory:

    BUG: unable to handle page fault for address: 0000000006400000
    #PF: supervisor write access in kernel mode
    #PF: error_code(0x0002) - not-present page
    PGD 0 P4D 0
    Oops: 0002 [#1] SMP PTI
    CPU: 3 PID: 221 Comm: kworker/u16:1 Tainted: G        W         5.5.0-next-20200205+ #343
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
    Workqueue: kacpi_hotplug acpi_hotplug_work_fn
    RIP: 0010:__memset+0x24/0x30
    Code: cc cc cc cc cc cc 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3
    RSP: 0018:ffffb43ac0373c80 EFLAGS: 00010a87
    RAX: ffffffffffffffff RBX: ffff8a1518800000 RCX: 0000000000050000
    RDX: 0000000000000000 RSI: 00000000000000ff RDI: 0000000006400000
    RBP: 0000000000140000 R08: 0000000000100000 R09: 0000000006400000
    R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000
    R13: 0000000000000028 R14: 0000000000000000 R15: ffff8a153ffd9280
    FS:  0000000000000000(0000) GS:ffff8a153ab00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000006400000 CR3: 0000000136fca000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     sparse_add_section+0x1c9/0x26a
     __add_pages+0xbf/0x150
     add_pages+0x12/0x60
     add_memory_resource+0xc8/0x210
     __add_memory+0x62/0xb0
     acpi_memory_device_add+0x13f/0x300
     acpi_bus_attach+0xf6/0x200
     acpi_bus_scan+0x43/0x90
     acpi_device_hotplug+0x275/0x3d0
     acpi_hotplug_work_fn+0x1a/0x30
     process_one_work+0x1a7/0x370
     worker_thread+0x30/0x380
     kthread+0x112/0x130
     ret_from_fork+0x35/0x40

We should use memmap as it did.

On x86 the impact is limited to x86_32 builds, or x86_64 configurations
that override the default setting for SPARSEMEM_VMEMMAP.

Other memory hotplug archs (arm64, ia64, and ppc) also default to
SPARSEMEM_VMEMMAP=y.

[dan.j.williams@intel.com: changelog update]
{rppt@linux.ibm.com: changelog update]
Link: http://lkml.kernel.org/r/20200219030454.4844-1-bhe@redhat.com
Fixes: ba72b4c8 ("mm/sparsemem: support sub-section hotplug")
Signed-off-by: NWei Yang <richardw.yang@linux.intel.com>
Signed-off-by: NBaoquan He <bhe@redhat.com>
Acked-by: NDavid Hildenbrand <david@redhat.com>
Reviewed-by: NBaoquan He <bhe@redhat.com>
Reviewed-by: NDan Williams <dan.j.williams@intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      18e19f19
    • G
      mm/vmscan.c: don't round up scan size for online memory cgroup · 76073c64
      由 Gavin Shan 提交于 
      Commit 68600f62 ("mm: don't miss the last page because of round-off
error") makes the scan size round up to @denominator regardless of the
memory cgroup's state, online or offline.  This affects the overall
reclaiming behavior: the corresponding LRU list is eligible for
reclaiming only when its size logically right shifted by @sc->priority
is bigger than zero in the former formula.

For example, the inactive anonymous LRU list should have at least 0x4000
pages to be eligible for reclaiming when we have 60/12 for
swappiness/priority and without taking scan/rotation ratio into account.

After the roundup is applied, the inactive anonymous LRU list becomes
eligible for reclaiming when its size is bigger than or equal to 0x1000
in the same condition.

    (0x4000 >> 12) * 60 / (60 + 140 + 1) = 1
    ((0x1000 >> 12) * 60) + 200) / (60 + 140 + 1) = 1

aarch64 has 512MB huge page size when the base page size is 64KB.  The
memory cgroup that has a huge page is always eligible for reclaiming in
that case.

The reclaiming is likely to stop after the huge page is reclaimed,
meaing the further iteration on @sc->priority and the silbing and child
memory cgroups will be skipped.  The overall behaviour has been changed.
This fixes the issue by applying the roundup to offlined memory cgroups
only, to give more preference to reclaim memory from offlined memory
cgroup.  It sounds reasonable as those memory is unlikedly to be used by
anyone.

The issue was found by starting up 8 VMs on a Ampere Mustang machine,
which has 8 CPUs and 16 GB memory.  Each VM is given with 2 vCPUs and
2GB memory.  It took 264 seconds for all VMs to be completely up and
784MB swap is consumed after that.  With this patch applied, it took 236
seconds and 60MB swap to do same thing.  So there is 10% performance
improvement for my case.  Note that KSM is disable while THP is enabled
in the testing.

         total     used    free   shared  buff/cache   available
   Mem:  16196    10065    2049       16        4081        3749
   Swap:  8175      784    7391
         total     used    free   shared  buff/cache   available
   Mem:  16196    11324    3656       24        1215        2936
   Swap:  8175       60    8115

Link: http://lkml.kernel.org/r/20200211024514.8730-1-gshan@redhat.com
Fixes: 68600f62 ("mm: don't miss the last page because of round-off error")
Signed-off-by: NGavin Shan <gshan@redhat.com>
Acked-by: NRoman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>	[4.20+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      76073c64
    • V
      mm/memcontrol.c: lost css_put in memcg_expand_shrinker_maps() · 75866af6
      由 Vasily Averin 提交于 
      for_each_mem_cgroup() increases css reference counter for memory cgroup
and requires to use mem_cgroup_iter_break() if the walk is cancelled.

Link: http://lkml.kernel.org/r/c98414fb-7e1f-da0f-867a-9340ec4bd30b@virtuozzo.com
Fixes: 0a4465d3 ("mm, memcg: assign memcg-aware shrinkers bitmap to memcg")
Signed-off-by: NVasily Averin <vvs@virtuozzo.com>
Acked-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NRoman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      75866af6
    • C
      mm/swapfile.c: fix a comment in sys_swapon() · fed98ef4
      由 Christoph Hellwig 提交于 
      claim_swapfile now always takes i_rwsem.

Link: http://lkml.kernel.org/r/20200114161225.309792-2-hch@lst.deSigned-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fed98ef4
  5. 20 2月, 2020 1 次提交
  7. 19 2月, 2020 1 次提交
  9. 08 2月, 2020 3 次提交
  11. 07 2月, 2020 2 次提交
  13. 04 2月, 2020 25 次提交