From: "Zi Yan" <ziy@nvidia.com>
To: "Jinjiang Tu" <tujinjiang@huawei.com>,
<akpm@linux-foundation.org>, <david@kernel.org>,
<luizcap@redhat.com>, <willy@infradead.org>,
<linmiaohe@huawei.com>, <svetly.todorov@memverge.com>,
<xu.xin16@zte.com.cn>, <chengming.zhou@linux.dev>,
<linux-fsdevel@vger.kernel.org>, <linux-mm@kvack.org>
Cc: <wangkefeng.wang@huawei.com>, <sunnanyong@huawei.com>
Subject: Re: [PATCH v2] fs/proc: fix KPF_KSM reported for all anonymous pages
Date: Fri, 26 Jun 2026 10:08:34 -0400 [thread overview]
Message-ID: <DJJ1GI9R9KYX.VRUNK0PHFG85@nvidia.com> (raw)
In-Reply-To: <20260626013252.2846774-1-tujinjiang@huawei.com>
On Thu Jun 25, 2026 at 9:32 PM EDT, Jinjiang Tu wrote:
> Reading /proc/kpageflags for any anonymous page returns KPF_KSM set, even
> when KSM is not in use. As a result, tools misclassify all anonymous pages
> as KSM merged.
>
> In stable_page_flags(), if the page is anonymous, then use (mapping &
> FOLIO_MAPPING_KSM) check to identify if the anonymous page is KSM page.
> However, FOLIO_MAPPING_KSM is FOLIO_MAPPING_ANON | FOLIO_MAPPING_ANON_KSM,
> (mapping & FOLIO_MAPPING_KSM) check returns true for all nonymous pages.
>
> To fix it, use FOLIO_MAPPING_ANON_KSM instead.
>
> Fixes: dee3d0bef2b0 ("proc: rewrite stable_page_flags()")
> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
> ---
> Changelog in v2:
> * use FOLIO_MAPPING_KSM to match explictly instead of use FOLIO_MAPPING_ANON_KSM
> only.
>
> fs/proc/page.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
LGTM. Thanks.
Acked-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
prev parent reply other threads:[~2026-06-26 14:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-26 1:32 [PATCH v2] fs/proc: fix KPF_KSM reported for all anonymous pages Jinjiang Tu
2026-06-26 2:09 ` xu.xin16
2026-06-26 6:28 ` Jinjiang Tu
2026-06-26 8:13 ` David Hildenbrand (Arm)
2026-06-26 9:02 ` Jinjiang Tu
2026-06-26 14:08 ` Zi Yan [this message]
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