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From: Minchan Kim <minchan@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	Yu Zhao <yuzhao@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
	stable@vger.kernel.org
Subject: Re: [PATCH 1/6] arm64: pgtable: Fix pte_accessible()
Date: Fri, 20 Nov 2020 08:03:21 -0800	[thread overview]
Message-ID: <20201120160321.GB3377168@google.com> (raw)
In-Reply-To: <20201120143557.6715-2-will@kernel.org>

On Fri, Nov 20, 2020 at 02:35:52PM +0000, Will Deacon wrote:
> pte_accessible() is used by ptep_clear_flush() to figure out whether TLB
> invalidation is necessary when unmapping pages for reclaim. Although our
> implementation is correct according to the architecture, returning true
> only for valid, young ptes in the absence of racing page-table
> modifications, this is in fact flawed due to lazy invalidation of old
> ptes in ptep_clear_flush_young() where we elide the expensive DSB
> instruction for completing the TLB invalidation.
> 
> Rather than penalise the aging path, adjust pte_accessible() to return
> true for any valid pte, even if the access flag is cleared.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 76c714be0e5e ("arm64: pgtable: implement pte_accessible()")
> Reported-by: Yu Zhao <yuzhao@google.com>
> Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>

  reply	other threads:[~2020-11-20 16:03 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-20 14:35 [PATCH 0/6] tlb: Fix access and (soft-)dirty bit management Will Deacon
2020-11-20 14:35 ` [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Will Deacon
2020-11-20 16:03   ` Minchan Kim [this message]
2020-11-20 19:53   ` Yu Zhao
2020-11-23 13:27   ` Catalin Marinas
2020-11-24 10:02   ` Anshuman Khandual
2020-11-20 14:35 ` [PATCH 2/6] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() Will Deacon
2020-11-20 17:09   ` Minchan Kim
2020-11-23 14:31     ` Catalin Marinas
2020-11-23 14:22   ` Catalin Marinas
2020-11-20 14:35 ` [PATCH 3/6] tlb: mmu_gather: Remove unused start/end arguments from tlb_finish_mmu() Will Deacon
2020-11-20 17:20   ` Linus Torvalds
2020-11-23 16:48     ` Will Deacon
2020-11-20 14:35 ` [PATCH 4/6] mm: proc: Invalidate TLB after clearing soft-dirty page state Will Deacon
2020-11-20 15:00   ` Peter Zijlstra
2020-11-20 15:09     ` Peter Zijlstra
2020-11-20 15:15     ` Will Deacon
2020-11-20 15:27       ` Peter Zijlstra
2020-11-23 18:23         ` Will Deacon
2020-11-20 15:55     ` Minchan Kim
2020-11-23 18:41       ` Will Deacon
2020-11-25 22:51         ` Minchan Kim
2020-11-20 20:22   ` Yu Zhao
2020-11-21  2:49     ` Yu Zhao
2020-11-23 19:21       ` Yu Zhao
2020-11-23 22:04       ` Will Deacon
2020-11-20 14:35 ` [PATCH 5/6] tlb: mmu_gather: Introduce tlb_gather_mmu_fullmm() Will Deacon
2020-11-20 17:22   ` Linus Torvalds
2020-11-20 17:31     ` Linus Torvalds
2020-11-23 16:48       ` Will Deacon
2021-02-01 11:32       ` [tip: core/mm] tlb: mmu_gather: Remove start/end arguments from tlb_gather_mmu() tip-bot2 for Will Deacon
2020-11-22 15:11   ` [tlb] e242a269fa: WARNING:at_mm/mmu_gather.c:#tlb_gather_mmu kernel test robot
2020-11-23 17:51     ` Will Deacon
2020-11-20 14:35 ` [PATCH 6/6] mm: proc: Avoid fullmm flush for young/dirty bit toggling Will Deacon
2020-11-20 17:41   ` Linus Torvalds
2020-11-20 17:45     ` Linus Torvalds
2020-11-20 20:40   ` Yu Zhao
2020-11-23 18:35     ` Will Deacon
2020-11-23 20:04       ` Yu Zhao
2020-11-23 21:17         ` Will Deacon
2020-11-24  1:13           ` Yu Zhao
2020-11-24 14:31             ` Will Deacon
2020-11-25 22:01             ` Minchan Kim
2020-11-24 14:46     ` Peter Zijlstra

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