From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Barry Song <baohua@kernel.org>, Ye Liu <ye.liu@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R. Howlett" <liam@infradead.org>,
Nico Pache <nico.pache@linux.dev>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Lance Yang <lance.yang@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Kiryl Shutsemau <kas@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Ye Liu <liuye@kylinos.cn>
Subject: Re: [PATCH] mm/huge_memory: use READ_ONCE() when cloning folio flags during split
Date: Thu, 29 Oct 2026 11:47:49 +0100 [thread overview]
Message-ID: <b5dccfe1-3209-471a-a34e-f77fffdee797@kernel.org> (raw)
In-Reply-To: <CAGsJ_4wndM+uFwhX+7wdkm2Q8AkgVcw_4wgpObfw0DAZ1w+sVQ@mail.gmail.com>
On 10/29/26 10:08, Barry Song wrote:
> On Thu, Oct 29, 2026 at 3:41 PM Ye Liu <ye.liu@linux.dev> wrote:
>>
>> From: Ye Liu <liuye@kylinos.cn>
>>
>> The head folio's flags are read as a whole word to clone specific bits
>> into tail folios during a THP split. This plain read can race with
>> concurrent atomic flag modifications such as folio_set_waiters()
>> (PG_waiters), as reported by KCSAN:
>>
>> BUG: KCSAN: data-race in __split_huge_page_tail / migration_entry_wait_on_locked
>>
>> Signed-off-by: Ye Liu <liuye@kylinos.cn>
>> ---
>
> I assume the race is harmless, but silencing KCSAN is still worthwhile.
Isn't there a way we could lose the PG_waiters flag?
--
Cheers,
David
next prev parent reply other threads:[~2026-10-29 10:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-29 7:41 [PATCH] mm/huge_memory: use READ_ONCE() when cloning folio flags during split Ye Liu
2026-10-29 9:08 ` Barry Song
2026-10-29 10:47 ` David Hildenbrand (Arm) [this message]
2026-10-29 14:31 ` Zi Yan
2026-10-29 14:54 ` David Hildenbrand (Arm)
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