linux-kernel - Re: [PATCH 2/2] mm/truncate: don't skip dirty page in folio_unmap

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Message-ID: <b2248d8c-1f80-4806-80fb-cbc40ad713e6@linux.alibaba.com>
Date: Wed, 19 Feb 2025 09:23:13 +0800
From: Jingbo Xu <jefflexu@...ux.alibaba.com>
To: "Kirill A. Shutemov" <kirill@...temov.name>, Jens Axboe <axboe@...nel.dk>
Cc: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, brauner@...nel.org,
 linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk
Subject: Re: [PATCH 2/2] mm/truncate: don't skip dirty page in
 folio_unmap_invalidate()

On 2/18/25 8:32 PM, Kirill A. Shutemov wrote:
> On Tue, Feb 18, 2025 at 08:02:09PM +0800, Jingbo Xu wrote:
>> ... otherwise this is a behavior change for the previous callers of
>> invalidate_complete_folio2(), e.g. the page invalidation routine.
> 
> Hm. Shouldn't the check be moved to caller of the helper in mm/filemap.c?
> 
> Otherwise we would drop pages without writing them back. And lose user's
> data.
> 

IMHO this check is not needed as the following folio_launder() called
inside folio_unmap_invalidate() will write back the dirty page.

Hi Jens,

What do you think about it?

-- 
Thanks,
Jingbo