From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
Arvind Yadav <arvind.yadav@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
matthew.brost@intel.com, joshua.hahnjy@gmail.com, ziy@nvidia.com,
rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net,
ying.huang@linux.alibaba.com, apopple@nvidia.com,
Balbir Singh <balbirs@nvidia.com>
Subject: Re: [PATCH v2] mm/migrate_device: Clear stale mapping after freeing swapcache
Date: Sat, 25 Jul 2026 21:36:12 +0200 [thread overview]
Message-ID: <2b2fe98d-1a7b-4aef-a1ff-0fbe43339180@kernel.org> (raw)
In-Reply-To: <20260724214307.a50ed52cf78fdc73bc42f9bf@linux-foundation.org>
On 7/25/26 06:43, Andrew Morton wrote:
> On Fri, 24 Jul 2026 13:57:02 +0530 Arvind Yadav <arvind.yadav@intel.com> wrote:
>
>> __migrate_device_pages() reads the folio mapping before calling
>> folio_free_swap(). When folio_free_swap() succeeds, the folio is removed
>> from the swap cache, but the saved mapping still points to swap_space.
>>
>> Passing the stale mapping to folio_migrate_mapping() makes it take the
>> mapped-folio path after the swapcache reference has been dropped. This can
>> cause an invalid swap_space lock access followed by a folio reference
>> count BUG.
>>
>> Refresh the saved mapping after folio_free_swap() so the current folio
>> state is used during migration.
>>
>
> Thanks. AI review might have found an issue with this. And one
> possible pre-existing issue in the code which Alistair and Balbir
> worked on.
>
> https://sashiko.dev/#/patchset/20260724082702.2531024-1-arvind.yadav@intel.com
Yeah, this might need another careful look.
--
Cheers,
David
next prev parent reply other threads:[~2026-07-25 19:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-24 8:27 [PATCH v2] mm/migrate_device: Clear stale mapping after freeing swapcache Arvind Yadav
2026-07-24 14:00 ` Zi Yan
2026-07-25 4:43 ` Andrew Morton
2026-07-25 19:36 ` David Hildenbrand (Arm) [this message]
2026-07-25 21:05 ` Zi Yan
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