From: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
Yu Zhao <yuzhao@google.com>, Minchan Kim <minchan@kernel.org>,
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: Mon, 23 Nov 2020 13:27:52 +0000 [thread overview]
Message-ID: <20201123132752.GE17833@gaia> (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: Catalin Marinas <catalin.marinas@arm.com>
next prev parent reply other threads:[~2020-11-23 13:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201120143557.6715-1-will@kernel.org>
2020-11-20 14:35 ` [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Will Deacon
2020-11-20 16:03 ` Minchan Kim
2020-11-20 19:53 ` Yu Zhao
2020-11-23 13:27 ` Catalin Marinas [this message]
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
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