lkml.org 
[lkml]   [2020]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/6] arm64: pgtable: Fix pte_accessible()
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>

\
 
 \ /
  Last update: 2020-11-20 17:05    [W:0.361 / U:0.188 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site