From 5d79472b622550f5ba931cfafe25b6285a0c8e06 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 3 Feb 2020 17:36:53 -0800 Subject: [PATCH] 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) Signed-off-by: Aneesh Kumar K.V Reported-by: "Aneesh Kumar K.V" Cc: Michael Ellerman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Adam W. Willis Signed-off-by: Forenche Signed-off-by: Carlos Ayrton Lopez Arroyo <15030201@itcelaya.edu.mx> --- include/asm-generic/tlb.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 729ffdde39de..bbe084c00ebf 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -397,7 +397,12 @@ 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);