* [PATCH 1/3] mm: make tlb_flush_pending global
2017-07-28 6:41 [PATCH 0/3] fix several TLB batch races Minchan Kim
@ 2017-07-28 6:41 ` Minchan Kim
2017-07-28 6:41 ` [PATCH 2/3] mm: fix MADV_[FREE|DONTNEED] TLB flush miss problem Minchan Kim
2017-07-28 6:41 ` [PATCH 3/3] mm: fix KSM data corruption Minchan Kim
2 siblings, 0 replies; 6+ messages in thread
From: Minchan Kim @ 2017-07-28 6:41 UTC (permalink / raw)
To: Andrew Morton
Cc: kernel-team, linux-mm, linux-kernel, Rik van Riel, Minchan Kim,
Nadav Amit, Mel Gorman
Currently, tlb_flush_pending is used only for CONFIG_[NUMA_BALANCING|
COMPACTION] but upcoming patches to solve subtle TLB flush bacting
problem will use it regardless of compaction/numa so this patch
doesn't remove the dependency.
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
include/linux/mm_types.h | 15 ---------------
kernel/fork.c | 2 --
mm/debug.c | 2 --
3 files changed, 19 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 4b9a625c370c..6953d2c706fe 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -487,14 +487,12 @@ struct mm_struct {
/* numa_scan_seq prevents two threads setting pte_numa */
int numa_scan_seq;
#endif
-#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
/*
* An operation with batched TLB flushing is going on. Anything that
* can move process memory needs to flush the TLB when moving a
* PROT_NONE or PROT_NUMA mapped page.
*/
atomic_t tlb_flush_pending;
-#endif
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
/* See flush_tlb_batched_pending() */
bool tlb_flush_batched;
@@ -522,7 +520,6 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
return mm->cpu_vm_mask_var;
}
-#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
/*
* Memory barriers to keep this state in sync are graciously provided by
* the page table locks, outside of which no page table modifications happen.
@@ -565,18 +562,6 @@ static inline void clear_tlb_flush_pending(struct mm_struct *mm)
smp_mb__before_atomic();
atomic_dec(&mm->tlb_flush_pending);
}
-#else
-static inline bool mm_tlb_flush_pending(struct mm_struct *mm, bool pt_locked)
-{
- return false;
-}
-static inline void set_tlb_flush_pending(struct mm_struct *mm)
-{
-}
-static inline void clear_tlb_flush_pending(struct mm_struct *mm)
-{
-}
-#endif
struct vm_fault;
diff --git a/kernel/fork.c b/kernel/fork.c
index aaf4d70afd8b..7e9f42060976 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -807,9 +807,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
mm_init_aio(mm);
mm_init_owner(mm, p);
mmu_notifier_mm_init(mm);
-#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
atomic_set(&mm->tlb_flush_pending, 0);
-#endif
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
mm->pmd_huge_pte = NULL;
#endif
diff --git a/mm/debug.c b/mm/debug.c
index d70103bb4731..18a9b15b1e37 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -158,9 +158,7 @@ void dump_mm(const struct mm_struct *mm)
#ifdef CONFIG_NUMA_BALANCING
mm->numa_next_scan, mm->numa_scan_offset, mm->numa_scan_seq,
#endif
-#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
atomic_read(&mm->tlb_flush_pending),
-#endif
mm->def_flags, &mm->def_flags
);
}
--
2.7.4
--
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/3] mm: fix MADV_[FREE|DONTNEED] TLB flush miss problem
2017-07-28 6:41 [PATCH 0/3] fix several TLB batch races Minchan Kim
2017-07-28 6:41 ` [PATCH 1/3] mm: make tlb_flush_pending global Minchan Kim
@ 2017-07-28 6:41 ` Minchan Kim
2017-07-28 8:46 ` Mel Gorman
2017-07-28 6:41 ` [PATCH 3/3] mm: fix KSM data corruption Minchan Kim
2 siblings, 1 reply; 6+ messages in thread
From: Minchan Kim @ 2017-07-28 6:41 UTC (permalink / raw)
To: Andrew Morton
Cc: kernel-team, linux-mm, linux-kernel, Rik van Riel, Minchan Kim,
Ingo Molnar, x86, Russell King, linux-arm-kernel, Tony Luck,
linux-ia64, Martin Schwidefsky, David S. Miller, Heiko Carstens,
linux-s390, Yoshinori Sato, linux-sh, Jeff Dike,
user-mode-linux-devel, linux-arch, Nadav Amit, Mel Gorman
Nadav reported parallel MADV_DONTNEED on same range has a stale TLB
problem and Mel fixed it[1] and found same problem on MADV_FREE[2].
Quote from Mel Gorman
"The race in question is CPU 0 running madv_free and updating some PTEs
while CPU 1 is also running madv_free and looking at the same PTEs.
CPU 1 may have writable TLB entries for a page but fail the pte_dirty
check (because CPU 0 has updated it already) and potentially fail to flush.
Hence, when madv_free on CPU 1 returns, there are still potentially writable
TLB entries and the underlying PTE is still present so that a subsequent write
does not necessarily propagate the dirty bit to the underlying PTE any more.
Reclaim at some unknown time at the future may then see that the PTE is still
clean and discard the page even though a write has happened in the meantime.
I think this is possible but I could have missed some protection in madv_free
that prevents it happening."
This patch aims for solving both problems all at once and is ready for
other problem with KSM, MADV_FREE and soft-dirty story[3].
TLB batch API(tlb_[gather|finish]_mmu] uses [set|clear]_tlb_flush_pending
and mmu_tlb_flush_pending so that when tlb_finish_mmu is called, we can catch
there are parallel threads going on. In that case, flush TLB to prevent
for user to access memory via stale TLB entry although it fail to gather
pte entry.
I confiremd this patch works with [4] test program Nadav gave so this patch
supersedes "mm: Always flush VMA ranges affected by zap_page_range v2"
in current mmotm.
NOTE:
This patch modifies arch-specific TLB gathering interface(x86, ia64,
s390, sh, um). It seems most of architecture are straightforward but s390
need to be careful because tlb_flush_mmu works only if mm->context.flush_mm
is set to non-zero which happens only a pte entry really is cleared by
ptep_get_and_clear and friends. However, this problem never changes the
pte entries but need to flush to prevent memory access from stale tlb.
Any thoughts?
[1] http://lkml.kernel.org/r/20170725101230.5v7gvnjmcnkzzql3@techsingularity.net
[2] http://lkml.kernel.org/r/20170725100722.2dxnmgypmwnrfawp@suse.de
[3] http://lkml.kernel.org/r/BD3A0EBE-ECF4-41D4-87FA-C755EA9AB6BD@gmail.com
[4] https://patchwork.kernel.org/patch/9861621/
Cc: Ingo Molnar <mingo@redhat.com>
Cc: x86@kernel.org
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: linux-sh@vger.kernel.org
Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: linux-arch@vger.kernel.org
Cc: Nadav Amit <nadav.amit@gmail.com>
Reported-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
arch/arm/include/asm/tlb.h | 15 ++++++++++++++-
arch/ia64/include/asm/tlb.h | 12 ++++++++++++
arch/s390/include/asm/tlb.h | 15 +++++++++++++++
arch/sh/include/asm/tlb.h | 4 +++-
arch/um/include/asm/tlb.h | 8 ++++++++
include/linux/mm_types.h | 7 +++++--
mm/memory.c | 24 ++++++++++++------------
7 files changed, 69 insertions(+), 16 deletions(-)
diff --git a/arch/arm/include/asm/tlb.h b/arch/arm/include/asm/tlb.h
index 3f2eb76243e3..8c26961f0503 100644
--- a/arch/arm/include/asm/tlb.h
+++ b/arch/arm/include/asm/tlb.h
@@ -163,13 +163,26 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb->batch = NULL;
#endif
+ set_tlb_flush_pending(tlb->mm);
}
static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
- tlb_flush_mmu(tlb);
+ /*
+ * If there are parallel threads are doing PTE changes on same range
+ * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
+ * flush by batching, a thread has stable TLB entry can fail to flush
+ * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
+ * if we detect parallel PTE batching threads.
+ */
+ if (mm_tlb_flush_pending(tlb->mm, false) > 1) {
+ tlb->range_start = start;
+ tlb->range_end = end;
+ }
+ tlb_flush_mmu(tlb);
+ clear_tlb_flush_pending(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
diff --git a/arch/ia64/include/asm/tlb.h b/arch/ia64/include/asm/tlb.h
index fced197b9626..22fe976a4693 100644
--- a/arch/ia64/include/asm/tlb.h
+++ b/arch/ia64/include/asm/tlb.h
@@ -178,6 +178,7 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start
tlb->start = start;
tlb->end = end;
tlb->start_addr = ~0UL;
+ set_tlb_flush_pending(tlb->mm);
}
/*
@@ -188,10 +189,21 @@ static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
/*
+ * If there are parallel threads are doing PTE changes on same range
+ * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
+ * flush by batching, a thread has stable TLB entry can fail to flush
+ * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
+ * if we detect parallel PTE batching threads.
+ */
+ if (mm_tlb_flush_pending(tlb->mm, false) > 1)
+ tlb->need_flush = 1;
+
+ /*
* Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
* tlb->end_addr.
*/
ia64_tlb_flush_mmu(tlb, start, end);
+ clear_tlb_flush_pending(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h
index 950af48e88be..69eede9f31e5 100644
--- a/arch/s390/include/asm/tlb.h
+++ b/arch/s390/include/asm/tlb.h
@@ -57,6 +57,8 @@ static inline void tlb_gather_mmu(struct mmu_gather *tlb,
tlb->end = end;
tlb->fullmm = !(start | (end+1));
tlb->batch = NULL;
+
+ set_tlb_flush_pending(tlb->mm);
}
static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
@@ -79,7 +81,20 @@ static inline void tlb_flush_mmu(struct mmu_gather *tlb)
static inline void tlb_finish_mmu(struct mmu_gather *tlb,
unsigned long start, unsigned long end)
{
+ /*
+ * If there are parallel threads are doing PTE changes on same range
+ * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
+ * flush by batching, a thread has stable TLB entry can fail to flush
+ * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
+ * if we detect parallel PTE batching threads.
+ */
+ if (mm_tlb_flush_pending(tlb->mm, false) > 1) {
+ tlb->start = start;
+ tlb->end = end;
+ }
+
tlb_flush_mmu(tlb);
+ clear_tlb_flush_pending(tlb->mm);
}
/*
diff --git a/arch/sh/include/asm/tlb.h b/arch/sh/include/asm/tlb.h
index 46e0d635e36f..37d1e247f0dc 100644
--- a/arch/sh/include/asm/tlb.h
+++ b/arch/sh/include/asm/tlb.h
@@ -44,14 +44,16 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start
tlb->fullmm = !(start | (end+1));
init_tlb_gather(tlb);
+ set_tlb_flush_pending(tlb->mm);
}
static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
- if (tlb->fullmm)
+ if (tlb->fullmm || mm_tlb_flush_pending(tlb->mm, false) > 1)
flush_tlb_mm(tlb->mm);
+ clear_tlb_flush_pending(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
}
diff --git a/arch/um/include/asm/tlb.h b/arch/um/include/asm/tlb.h
index 600a2e9bfee2..8938c4914bd0 100644
--- a/arch/um/include/asm/tlb.h
+++ b/arch/um/include/asm/tlb.h
@@ -53,6 +53,7 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start
tlb->fullmm = !(start | (end+1));
init_tlb_gather(tlb);
+ set_tlb_flush_pending(tlb->mm);
}
extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
@@ -87,7 +88,14 @@ tlb_flush_mmu(struct mmu_gather *tlb)
static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
+ if (mm_tlb_flush_pending(tlb->mm, false) > 1) {
+ tlb->start = start;
+ tlb->end = end;
+ tlb->need_flush = 1;
+ }
+
tlb_flush_mmu(tlb);
+ clear_tlb_flush_pending(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 6953d2c706fe..8bb0dfc004be 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -527,8 +527,9 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
* which happen while the lock is not taken, and the PTE updates, which happen
* while the lock is taken, are serialized.
*/
-static inline bool mm_tlb_flush_pending(struct mm_struct *mm, bool pt_locked)
+static inline int mm_tlb_flush_pending(struct mm_struct *mm, bool pt_locked)
{
+ int nr_pending;
/*
* mm_tlb_flush_pending() is safe if it is executed while the page-table
* lock is taken. But if the lock was already released, there does not
@@ -538,8 +539,10 @@ static inline bool mm_tlb_flush_pending(struct mm_struct *mm, bool pt_locked)
if (!pt_locked)
smp_mb__after_unlock_lock();
- return atomic_read(&mm->tlb_flush_pending) > 0;
+ nr_pending = atomic_read(&mm->tlb_flush_pending);
+ return nr_pending;
}
+
static inline void set_tlb_flush_pending(struct mm_struct *mm)
{
atomic_inc(&mm->tlb_flush_pending);
diff --git a/mm/memory.c b/mm/memory.c
index ea9f28e44b81..7861d3556c6e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -239,6 +239,7 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
tlb->page_size = 0;
__tlb_reset_range(tlb);
+ set_tlb_flush_pending(tlb->mm);
}
static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
@@ -278,8 +279,18 @@ void tlb_flush_mmu(struct mmu_gather *tlb)
void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
struct mmu_gather_batch *batch, *next;
+ /*
+ * If there are parallel threads are doing PTE changes on same range
+ * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
+ * flush by batching, a thread has stable TLB entry can fail to flush
+ * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
+ * if we detect parallel PTE batching threads.
+ */
+ if (mm_tlb_flush_pending(tlb->mm, false) > 1)
+ __tlb_adjust_range(tlb, start, end - start);
tlb_flush_mmu(tlb);
+ clear_tlb_flush_pending(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
@@ -1485,20 +1496,9 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long start,
tlb_gather_mmu(&tlb, mm, start, end);
update_hiwater_rss(mm);
mmu_notifier_invalidate_range_start(mm, start, end);
- for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
+ for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
unmap_single_vma(&tlb, vma, start, end, NULL);
- /*
- * zap_page_range does not specify whether mmap_sem should be
- * held for read or write. That allows parallel zap_page_range
- * operations to unmap a PTE and defer a flush meaning that
- * this call observes pte_none and fails to flush the TLB.
- * Rather than adding a complex API, ensure that no stale
- * TLB entries exist when this call returns.
- */
- flush_tlb_range(vma, start, end);
- }
-
mmu_notifier_invalidate_range_end(mm, start, end);
tlb_finish_mmu(&tlb, start, end);
}
--
2.7.4
--
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 3/3] mm: fix KSM data corruption
2017-07-28 6:41 [PATCH 0/3] fix several TLB batch races Minchan Kim
2017-07-28 6:41 ` [PATCH 1/3] mm: make tlb_flush_pending global Minchan Kim
2017-07-28 6:41 ` [PATCH 2/3] mm: fix MADV_[FREE|DONTNEED] TLB flush miss problem Minchan Kim
@ 2017-07-28 6:41 ` Minchan Kim
2 siblings, 0 replies; 6+ messages in thread
From: Minchan Kim @ 2017-07-28 6:41 UTC (permalink / raw)
To: Andrew Morton
Cc: kernel-team, linux-mm, linux-kernel, Rik van Riel, Minchan Kim,
Nadav Amit, Mel Gorman, Hugh Dickins, Andrea Arcangeli
Nadav reported KSM can corrupt the user data by the TLB batching race[1].
That means data user written can be lost.
Quote from Nadav Amit
"
For this race we need 4 CPUs:
CPU0: Caches a writable and dirty PTE entry, and uses the stale value for
write later.
CPU1: Runs madvise_free on the range that includes the PTE. It would clear
the dirty-bit. It batches TLB flushes.
CPU2: Writes 4 to /proc/PID/clear_refs , clearing the PTEs soft-dirty. We
care about the fact that it clears the PTE write-bit, and of course, batches
TLB flushes.
CPU3: Runs KSM. Our purpose is to pass the following test in
write_protect_page():
if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) ||
(pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte)))
Since it will avoid TLB flush. And we want to do it while the PTE is stale.
Later, and before replacing the page, we would be able to change the page.
Note that all the operations the CPU1-3 perform canhappen in parallel since
they only acquire mmap_sem for read.
We start with two identical pages. Everything below regards the same
page/PTE.
CPU0 CPU1 CPU2 CPU3
---- ---- ---- ----
Write the same
value on page
[cache PTE as
dirty in TLB]
MADV_FREE
pte_mkclean()
4 > clear_refs
pte_wrprotect()
write_protect_page()
[ success, no flush ]
pages_indentical()
[ ok ]
Write to page
different value
[Ok, using stale
PTE]
replace_page()
Later, CPU1, CPU2 and CPU3 would flush the TLB, but that is too late. CPU0
already wrote on the page, but KSM ignored this write, and it got lost.
"
In above scenario, MADV_FREE is fixed by changing TLB batching API
including [set|clear]_tlb_flush_pending. Remained thing is soft-dirty part.
This patch changes soft-dirty uses TLB batching API instead of flush_tlb_mm
and KSM checks pending TLB flush by using mm_tlb_flush_pending so that
it will flush TLB to avoid data lost if there are other parallel threads
pending TLB flush.
[1] http://lkml.kernel.org/r/BD3A0EBE-ECF4-41D4-87FA-C755EA9AB6BD@gmail.com
Note:
I failed to reproduce this problem through Nadav's test program which
need to tune timing in my system speed so didn't confirm it work.
Nadav, Could you test this patch on your test machine?
Thanks!
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
fs/proc/task_mmu.c | 4 +++-
mm/ksm.c | 3 ++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 35be35e05153..583fc50eb36d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1019,6 +1019,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
enum clear_refs_types type;
int itype;
int rv;
+ struct mmu_gather tlb;
memset(buffer, 0, sizeof(buffer));
if (count > sizeof(buffer) - 1)
@@ -1063,6 +1064,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
}
down_read(&mm->mmap_sem);
+ tlb_gather_mmu(&tlb, mm, 0, -1);
if (type == CLEAR_REFS_SOFT_DIRTY) {
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (!(vma->vm_flags & VM_SOFTDIRTY))
@@ -1084,7 +1086,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
walk_page_range(0, mm->highest_vm_end, &clear_refs_walk);
if (type == CLEAR_REFS_SOFT_DIRTY)
mmu_notifier_invalidate_range_end(mm, 0, -1);
- flush_tlb_mm(mm);
+ tlb_finish_mmu(&tlb, 0, -1);
up_read(&mm->mmap_sem);
out_mm:
mmput(mm);
diff --git a/mm/ksm.c b/mm/ksm.c
index 4dc92f138786..d3b1c70aac18 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1038,7 +1038,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
goto out_unlock;
if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte) ||
- (pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte))) {
+ (pte_protnone(*pvmw.pte) && pte_savedwrite(*pvmw.pte)) ||
+ mm_tlb_flush_pending(mm, true)) {
pte_t entry;
swapped = PageSwapCache(page);
--
2.7.4
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