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Subject: Re: [PATCH v5 10/13] mm: page_vma_mapped_walk: map_pte() use
 pte_offset_map_rw_nolock()
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From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <2620a48f34c9f19864ab0169cdbf253d31a8fcaa.1727332572.git.zhengqi.arch@bytedance.com>
Date: Thu, 26 Sep 2024 15:08:38 +0800
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References: <cover.1727332572.git.zhengqi.arch@bytedance.com>
 <2620a48f34c9f19864ab0169cdbf253d31a8fcaa.1727332572.git.zhengqi.arch@bytedance.com>
To: Qi Zheng <zhengqi.arch@bytedance.com>
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> On Sep 26, 2024, at 14:46, Qi Zheng <zhengqi.arch@bytedance.com> wrote:
> 
> In the caller of map_pte(), we may modify the pvmw->pte after acquiring
> the pvmw->ptl, so convert it to using pte_offset_map_rw_nolock(). At
> this time, the pte_same() check is not performed after the pvmw->ptl held,
> so we should get pmdval and do pmd_same() check to ensure the stability of
> pvmw->pmd.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>

Reviewed-by: Muchun Song <muchun.song@linux.dev>

Thanks.