linux-kernel - Re: [PATCH v2 06/11] don't put symlink bodies in pagecache into highmem

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Message-ID: <20160114171341.GY17997@ZenIV.linux.org.uk>
Date:	Thu, 14 Jan 2016 17:13:41 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Tomeu Vizoso <tomeu@...euvizoso.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Neil Brown <neilb@...e.com>, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 06/11] don't put symlink bodies in pagecache into
 highmem

On Thu, Jan 14, 2016 at 05:57:42PM +0100, Tomeu Vizoso wrote:
> Here it is:
> 
> [  170.715356] inode: ec8c30b0, pages: 1
> [  170.719014] page_address:   (null)
> 
> https://lava.collabora.co.uk/scheduler/job/127698/log_file

	Lovely...  And that looks like the first time that inode hits
nfs_get_link().  Ho-hum...

	Could you add WARN_ON(inode->i_mapping.nrpages) in inode_nohighmem()
and see if that triggers?  It really shouldn't (we hit it after iget5_locked()
in nfs_fhget() has returned us a new inode, and there shouldn't be a chance
for any pages to get in there between struct inode allocation and that
point), but then neither should highmem pages be added to address_space
without __GFP_HIGHMEM in ->flags...