From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: akpm@linux-foundation.org, peterz@infradead.org, will@kernel.org,
mpe@ellerman.id.au
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: [PATCH v4 3/9] asm-generic/tlb: Avoid potential double flush
Date: Thu, 16 Jan 2020 12:15:25 +0530 [thread overview]
Message-ID: <20200116064531.483522-4-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200116064531.483522-1-aneesh.kumar@linux.ibm.com>
From: Peter Zijlstra <peterz@infradead.org>
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.
Reported-by: "Aneesh Kumar K.V" <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>
---
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 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);
--
2.24.1
next prev parent reply other threads:[~2020-01-16 6:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 6:45 [PATCH v4 0/9] Fixup page directory freeing Aneesh Kumar K.V
2020-01-16 6:45 ` [PATCH v4 1/9] powerpc/mmu_gather: Enable RCU_TABLE_FREE even for !SMP case Aneesh Kumar K.V
2020-01-18 11:01 ` Michael Ellerman
2020-01-16 6:45 ` [PATCH v4 2/9] mm/mmu_gather: Invalidate TLB correctly on batch allocation failure and flush Aneesh Kumar K.V
2020-01-18 11:04 ` Michael Ellerman
2020-01-16 6:45 ` Aneesh Kumar K.V [this message]
2020-01-16 6:49 ` [PATCH v4 3/9] asm-generic/tlb: Avoid potential double flush Aneesh Kumar K.V
2020-01-17 1:46 ` Andrew Morton
2020-01-16 6:45 ` [PATCH v4 4/9] asm-gemeric/tlb: Remove stray function declarations Aneesh Kumar K.V
2020-01-16 6:45 ` [PATCH v4 5/9] asm-generic/tlb: Add missing CONFIG symbol Aneesh Kumar K.V
2020-01-16 6:45 ` [PATCH v4 6/9] asm-generic/tlb: Rename HAVE_RCU_TABLE_FREE Aneesh Kumar K.V
2020-01-18 5:56 ` Aneesh Kumar K.V
2020-01-16 6:45 ` [PATCH v4 7/9] asm-generic/tlb: Rename HAVE_MMU_GATHER_PAGE_SIZE Aneesh Kumar K.V
2020-01-16 6:45 ` [PATCH v4 8/9] asm-generic/tlb: Rename HAVE_MMU_GATHER_NO_GATHER Aneesh Kumar K.V
2020-01-16 6:45 ` [PATCH v4 9/9] asm-generic/tlb: Provide MMU_GATHER_TABLE_FREE Aneesh Kumar K.V
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