From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Jinjiang Tu <tujinjiang@huawei.com>,
akpm@linux-foundation.org, ziy@nvidia.com, 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 10:13:53 +0200 [thread overview]
Message-ID: <a63b7138-617f-46de-96f9-e56528aee3aa@kernel.org> (raw)
In-Reply-To: <20260626013252.2846774-1-tujinjiang@huawei.com>
On 6/26/26 03:32, 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>
> ---
With spelling fix
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
And I'd appreciate if someone could look into cleaning up the code to switch
back to folio helpers now that we have folio+page snapshots.
--
Cheers,
David
next prev parent reply other threads:[~2026-06-26 8:14 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) [this message]
2026-06-26 9:02 ` Jinjiang Tu
2026-06-26 14:08 ` Zi Yan
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