From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + asm-generic-tlb-avoid-potential-double-flush.patch added to -mm tree Date: Thu, 16 Jan 2020 17:53:51 -0800 Message-ID: <20200117015351.h--YZ%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:47674 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726741AbgAQBxw (ORCPT ); Thu, 16 Jan 2020 20:53:52 -0500 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: mm-commits@vger.kernel.org, mpe@ellerman.id.au, aneesh.kumar@linux.ibm.com, peterz@infradead.org The patch titled Subject: asm-generic/tlb: avoid potential double flush has been added to the -mm tree. Its filename is asm-generic-tlb-avoid-potential-double-flush.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/asm-generic-tlb-avoid-potential-double-flush.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/asm-generic-tlb-avoid-potential-double-flush.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Peter Zijlstra Subject: 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 --- include/asm-generic/tlb.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/include/asm-generic/tlb.h~asm-generic-tlb-avoid-potential-double-flush +++ a/include/asm-generic/tlb.h @@ -402,7 +402,12 @@ tlb_update_vma_flags(struct mmu_gather * 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); _ Patches currently in -mm which might be from peterz@infradead.org are mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush.patch asm-generic-tlb-avoid-potential-double-flush.patch asm-gemeric-tlb-remove-stray-function-declarations.patch asm-generic-tlb-add-missing-config-symbol.patch asm-generic-tlb-rename-have_rcu_table_free.patch asm-generic-tlb-rename-have_mmu_gather_page_size.patch asm-generic-tlb-rename-have_mmu_gather_no_gather.patch asm-generic-tlb-provide-mmu_gather_table_free.patch