lkml.org 
[lkml]   [2022]   [Aug]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 1/2] mm/damon: validate if the pmd entry is present before accessing
From
Date


> On Aug 18, 2022, at 15:37, Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
>
> The pmd_huge() is used to validate if the pmd entry is mapped by a huge
> page, also including the case of non-present (migration or hwpoisoned)
> pmd entry on arm64 or x86 architectures. That means the pmd_pfn() can
> not get the correct pfn number for the non-present pmd entry, which
> will cause damon_get_page() to get an incorrect page struct (also
> may be NULL by pfn_to_online_page()) to make the access statistics
> incorrect.
>
> Moreover it does not make sense that we still waste time to get the
> page of the non-present entry, just treat it as not-accessed and skip it,
> that keeps consistent with non-present pte level entry.
>
> Thus adding a pmd entry present validation to fix above issues.
>
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Reviewed-by: SeongJae Park <sj@kernel.org>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks.

\
 
 \ /
  Last update: 2022-08-18 10:28    [W:0.079 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site