linux-kernel - Re: [PATCH v3 2/4] mm/damon/ops-common: atomically test and clear young on ptes and pmds

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Message-ID: <640f81aa-035e-9f42-c848-096e4c9e014c@arm.com>
Date:   Fri, 2 Jun 2023 18:14:25 +0100
From:   Ryan Roberts <ryan.roberts@....com>
To:     Yu Zhao <yuzhao@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        SeongJae Park <sj@...nel.org>,
        Christoph Hellwig <hch@...radead.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Uladzislau Rezki <urezki@...il.com>, Zi Yan <ziy@...dia.com>,
        Mike Rapoport <rppt@...nel.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, damon@...ts.linux.dev
Subject: Re: [PATCH v3 2/4] mm/damon/ops-common: atomically test and clear
 young on ptes and pmds

On 02/06/2023 17:35, Yu Zhao wrote:
> On Fri, Jun 2, 2023 at 3:30 AM Ryan Roberts <ryan.roberts@....com> wrote:
>>
>> It is racy to non-atomically read a pte, then clear the young bit, then
>> write it back as this could discard dirty information. Further, it is
>> bad practice to directly set a pte entry within a table. Instead
>> clearing young must go through the arch-provided helper,
>> ptep_test_and_clear_young() to ensure it is modified atomically and to
>> give the arch code visibility and allow it to check (and potentially
>> modify) the operation.
>>
>> Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces").
> 
> Just to double check: was "Cc: stable@...r.kernel.org" overlooked or
> deemed unnecessary?

It was overlooked - incompetance strikes again! I was intending to cc the whole
series. What's the best way to fix this? Can I just add stable in cc on reply to
the cover letter or will I have to resend the lot?

> 
>> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
>> Reviewed-by: Zi Yan <ziy@...dia.com>
>> Reviewed-by: SeongJae Park <sj@...nel.org>
>> Reviewed-by: Mike Rapoport (IBM) <rppt@...nel.org>