linux-kernel - Re: [PATCH 4.4 035/108] dont put symlink bodies in pagecache into highmem

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Message-ID: <1520210279.2786.53.camel@codethink.co.uk>
Date:   Mon, 05 Mar 2018 00:37:59 +0000
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Jin Qian <jinqian@...gle.com>, Jin Qian <jinqian@...roid.com>
Subject: Re: [PATCH 4.4 035/108] dont put symlink bodies in pagecache into
 highmem

On Thu, 2018-02-15 at 16:16 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Al Viro <viro@...iv.linux.org.uk>
> 
> commit 21fc61c73c3903c4c312d0802da01ec2b323d174 upstream.
> 
> kmap() in page_follow_link_light() needed to go - allowing to hold
> an arbitrary number of kmaps for long is a great way to deadlocking
> the system.
> 
> new helper (inode_nohighmem(inode)) needs to be used for pagecache
> symlinks inodes; done for all in-tree cases.  page_follow_link_light()
> instrumented to yell about anything missed.

Except that this backport only updates ext4 and f2fs (and doesn't add
the warning).  I suppose that's all matters for Android, but it would
be nice to get a more complete backport into 4.4-stable...

Ben.

> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> Signed-off-by: Jin Qian <jinqian@...gle.com>
> Signed-off-by: Jin Qian <jinqian@...roid.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[...]

-- 
Ben Hutchings
Software Developer, Codethink Ltd.