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authorPeter Zijlstra <peterz@infradead.org>2020-02-03 17:36:53 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-02-04 03:05:26 +0000
commit0758cd8304942292e95a0f750c374533db378b32 (patch)
treefdfe709ddee4d1781db6a36fbdea1c31a60ebc01 /include
parent0ed1325967ab5f7a4549a2641c6ebe115f76e228 (diff)
downloadlinux-0758cd8304942292e95a0f750c374533db378b32.tar.bz2
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/20200116064531.483522-4-aneesh.kumar@linux.ibm.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Reported-by: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/tlb.h7
1 files changed, 6 insertions, 1 deletions
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 9e22ac369d1d..b36b3bef5661 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -402,7 +402,12 @@ tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { }
static inline 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);