Messages in this thread | | | Date | Fri, 20 Nov 2020 08:03:21 -0800 | From | Minchan Kim <> | Subject | Re: [PATCH 1/6] arm64: pgtable: Fix pte_accessible() |
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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>
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