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Date: Mon, 24 Jun 2024 16:57:30 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Yang Erkun <yangerkun@huawei.com>
Cc: sfrench@samba.org, pc@manguebit.com, ronniesahlberg@gmail.com,
	sprasad@microsoft.com, tom@talpey.com, bharathsm@microsoft.com,
	dhowells@redhat.com, linux-cifs@vger.kernel.org,
	stable@vger.kernel.org, stable-commits@vger.kernel.org,
	yangerkun@huaweicloud.com
Subject: Re: [PATCH 6.6~6.9] cifs: fix pagecache leak when do writepages
Message-ID: <2024062422-imaging-evaluate-3f85@gregkh>
References: <20240624042815.2242201-1-yangerkun@huawei.com>
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In-Reply-To: <20240624042815.2242201-1-yangerkun@huawei.com>

On Mon, Jun 24, 2024 at 12:28:15PM +0800, Yang Erkun wrote:
> After commit f3dc1bdb6b0b("cifs: Fix writeback data corruption"), the
> writepages for cifs will find all folio needed writepage with two phase.
> The first folio will be found in cifs_writepages_begin, and the latter
> various folios will be found in cifs_extend_writeback.
> 
> All those will first get folio, and for normal case, once we set page
> writeback and after do really write, we should put the reference, folio
> found in cifs_extend_writeback do this with folio_batch_release. But the
> folio found in cifs_writepages_begin never get the chance do it. And
> every writepages call, we will leak a folio(found this problem while do
> xfstests over cifs).
> 
> Besides, the exist path seem never handle this folio correctly, fix it too
> with this patch.
> 
> The problem does not exist in mainline since writepages path for cifs
> has changed to netfs. It's had to backport all related change, so try fix
> this problem with this single patch.
> 
> Fixes: f3dc1bdb6b0b ("cifs: Fix writeback data corruption")
> Signed-off-by: Yang Erkun <yangerkun@huawei.com>
> ---
>  fs/smb/client/file.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>