From: SeongJae Park <sj@kernel.org>
To: SeongJae Park <sj@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>, Yu Zhao <yuzhao@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Uladzislau Rezki <urezki@gmail.com>, Zi Yan <ziy@nvidia.com>,
Mike Rapoport <rppt@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
damon@lists.linux.dev
Subject: Re: [PATCH v3 2/4] mm/damon/ops-common: atomically test and clear young on ptes and pmds
Date: Fri, 2 Jun 2023 21:43:47 +0000 [thread overview]
Message-ID: <20230602214347.85694-1-sj@kernel.org> (raw)
In-Reply-To: <20230602191501.85553-1-sj@kernel.org>
On Fri, 2 Jun 2023 19:15:01 +0000 SeongJae Park <sj@kernel.org> wrote:
> Hi Ryan,
>
> On Fri, 2 Jun 2023 18:14:25 +0100 Ryan Roberts <ryan.roberts@arm.com> wrote:
>
> > On 02/06/2023 17:35, Yu Zhao wrote:
> > > On Fri, Jun 2, 2023 at 3:30 AM Ryan Roberts <ryan.roberts@arm.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@vger.kernel.org" overlooked or
> > > deemed unnecessary?
> >
> > It was overlooked - incompetance strikes again! I was intending to cc the
> > whole series.
>
> Not the whole patches in this series but only this patch is intended to be
> merged in stable series, right? If I'm not wrong, you could add
> 'Cc: <stable@vger.kernel.org>' tag here[1] when resending, to let stable kernel
> maintainers easily understand exactly what patches should be merged in the
> stable kernels. So, you wouldn't need to touch coverletter or cc whole series
> but only this one.
>
> [1] https://www.kernel.org/doc/html/v4.10/process/stable-kernel-rules.html
And I just found Andrew added the tag while adding this to the -mm queue.
Thank you, Andrew!
[1] https://lore.kernel.org/mm-commits/20230602205509.9DFBDC433D2@smtp.kernel.org/
Thanks,
SJ
>
>
> Thanks,
> SJ
>
next prev parent reply other threads:[~2023-06-02 21:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-02 9:29 [PATCH v3 0/4] Fixes for pte encapsulation bypasses Ryan Roberts
2023-06-02 9:29 ` [PATCH v3 1/4] mm: vmalloc must set pte via arch code Ryan Roberts
2023-06-02 9:29 ` [PATCH v3 2/4] mm/damon/ops-common: atomically test and clear young on ptes and pmds Ryan Roberts
2023-06-02 16:35 ` Yu Zhao
2023-06-02 17:14 ` Ryan Roberts
2023-06-02 17:35 ` Yu Zhao
2023-06-02 19:15 ` SeongJae Park
2023-06-02 21:43 ` SeongJae Park [this message]
2023-06-03 18:20 ` Ryan Roberts
2023-06-02 9:29 ` [PATCH v3 3/4] mm/damon/ops-common: Refactor to use {pte|pmd}p_clear_young_notify() Ryan Roberts
2023-06-02 16:28 ` Yu Zhao
2023-06-02 21:54 ` SeongJae Park
2023-06-02 9:29 ` [PATCH v3 4/4] mm: Fix failure to unmap pte on highmem systems Ryan Roberts
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