linux-kernel - Re: [PATCH v4 0/3] mm/khugepaged: fix khugepaged+shmem races

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Date:   Fri, 17 Feb 2023 11:37:17 +0100
From:   Miko Larsson <mikoxyzzz@...il.com>
To:     David Stevens <stevensd@...omium.org>, linux-mm@...ck.org,
        Peter Xu <peterx@...hat.com>,
        Matthew Wilcox <willy@...radead.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Yang Shi <shy828301@...il.com>,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/3] mm/khugepaged: fix khugepaged+shmem races

On Fri, 2023-02-17 at 17:54 +0900, David Stevens wrote:
> From: David Stevens <stevensd@...omium.org>
> 
> Fix two races in khugepaged+shmem that cause issues with userfaultfd
> and
> lseek, respectively.
> 
> v3 -> v4:
>  - Base changes on mm-everything (fba720cb4dc0)
>  - Add patch to refactor error handling control flow in collapse_file
>  - Rebase userfaultfd patch with no significant logic changes
>  - Different approach for fixing lseek race
> v2 -> v3:
>  - Use XA_RETRY_ENTRY to synchronize with reads from the page cache
>    under the RCU read lock in userfaultfd fix
>  - Add patch to fix lseek race
> v1 -> v2:
>  - Different approach for userfaultfd fix
> 
> David Stevens (3):
>   mm/khugepaged: refactor collapse_file control flow
>   mm/khugepaged: skip shmem with userfaultfd
>   mm/khugepaged: maintain page cache uptodate flag
> 
>  include/trace/events/huge_memory.h |   3 +-
>  mm/khugepaged.c                    | 263 ++++++++++++++++-----------
> --
>  2 files changed, 144 insertions(+), 122 deletions(-)
> 

Might want to Cc this to the stable mailing list.
-- 
~miko