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

[Greg Kroah-Hartman]

On Mon, Mar 05, 2018 at 12:37:59AM +0000, Ben Hutchings wrote:
> 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@xxxxxxxxxxxxxxxxxx>
> > 
> > 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...

That should be all the in-tree users of this, for 4.4, right?  If not,
ick.  Jin, can you look into this?

thanks,

greg k-h