From quic_charante@quicinc.com Wed Dec 20 02:53:35 2023
From: Charan Teja Kalla <quic_charante@quicinc.com>
To: linux-stable-mirror@lists.linaro.org
Subject: Re: + mm-migrate-high-order-folios-in-swap-cache-correctly.patch
 added to mm-hotfixes-unstable branch
Date: Wed, 20 Dec 2023 08:22:46 +0530
Message-ID: <ab0fa643-8c6b-d7b7-6d21-066e27469b9e@quicinc.com>
In-Reply-To: <20231214221150.7EC0DC433C9@smtp.kernel.org>
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Hi Andrew,

On 12/15/2023 3:41 AM, Andrew Morton wrote:
> Large folios occupy N consecutive entries in the swap cache instead of
> using multi-index entries like the page cache.  However, if a large folio
> is re-added to the LRU list, it can be migrated.  The migration code was
> not aware of the difference between the swap cache and the page cache and
> assumed that a single xas_store() would be sufficient.
>=20
> This leaves potentially many stale pointers to the now-migrated folio in
> the swap cache, which can lead to almost arbitrary data corruption in the
> future.  This can also manifest as infinite loops with the RCU read lock
> held.
>=20
> [willy(a)infradead.org: modifications to the changelog & tweaked the fix]
> Fixes: 3417013e0d183be ("mm/migrate: Add folio_migrate_mapping()")
> Link: https://lkml.kernel.org/r/20231214045841.961776-1-willy(a)infradead.o=
rg
> Signed-off-by: Charan Teja Kalla <quic_charante(a)quicinc.com>
> Signed-off-by: Matthew Wilcox (Oracle) <willy(a)infradead.org>
> Reported-by: Charan Teja Kalla <quic_charante(a)quicinc.com>
>   Closes: https://lkml.kernel.org/r/1700569840-17327-1-git-send-email-quic_=
charante(a)quicinc.com
> Cc: David Hildenbrand <david(a)redhat.com>
> Cc: Johannes Weiner <hannes(a)cmpxchg.org>
> Cc: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com>
> Cc: Naoya Horiguchi <n-horiguchi(a)ah.jp.nec.com>
> Cc: Shakeel Butt <shakeelb(a)google.com>
> Cc: <stable(a)vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>

Errors were reported from checkpatch.pl.

1) Seems we have used 15chars of sha1.
2) space before Closes:

Summary:

WARNING:BAD_FIXES_TAG: Please use correct Fixes: style 'Fixes: <12 chars
of sha1> ("<title line>")' - ie: 'Fixes: 3417013e0d18 ("mm/migrate: Add
folio_migrate_mapping()")'
#21:
--
WARNING:BAD_REPORTED_BY_LINK: Reported-by: should be immediately
followed by Closes: with a URL to the report
#26:


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