The commit is pushed to "branch-rh7-3.10.0-1127.10.1.vz7.162.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1127.10.1.vz7.162.13
------>
commit f64be64b0e3d460cd44eef5371e2142e8099bdc4
Author: Peter Zijlstra <[email protected]>
Date: Tue Jul 21 17:58:56 2020 +0300
asm-generic/tlb: avoid potential double flush
Aneesh reported that:
tlb_flush_mmu()
tlb_flush_mmu_tlbonly()
tlb_flush() <-- #1
tlb_flush_mmu_free()
tlb_table_flush()
tlb_table_invalidate()
tlb_flush_mmu_tlbonly()
tlb_flush() <-- #2
does two TLBIs when tlb->fullmm, because __tlb_reset_range() will not
clear tlb->end in that case.
Observe that any caller to __tlb_adjust_range() also sets at least one of
the tlb->freed_tables || tlb->cleared_p* bits, and those are
unconditionally cleared by __tlb_reset_range().
Change the condition for actually issuing TLBI to having one of those bits
set, as opposed to having tlb->end != 0.
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Aneesh Kumar K.V <[email protected]>
Reported-by: "Aneesh Kumar K.V" <[email protected]>
Cc: Michael Ellerman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
https://jira.sw.ru/browse/PSBM-101300
(cherry picked from commit 0758cd8304942292e95a0f750c374533db378b32)
Signed-off-by: Andrey Ryabinin <[email protected]>
---
mm/memory.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index f4874a2b8be84..4370dd4008220 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -252,8 +252,14 @@ void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct
mm_struct *mm,
static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
- if (!tlb->end)
+ /*
+ * Anything calling __tlb_adjust_range() also sets at least one of
+ * these bits.
+ */
+ if (!(tlb->freed_tables || tlb->cleared_ptes || tlb->cleared_pmds ||
+ tlb->cleared_puds || tlb->cleared_p4ds))
return;
+
tlb_flush(tlb);
mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
__tlb_reset_range(tlb);
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