From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@ZenIV.linux.org.uk>,
<linux-fsdevel@vger.kernel.org>, <linux-mm@kvack.org>,
lustre-devel@lists.lustre.org, cluster-devel@redhat.com
Subject: Re: [PATCH] mm: Avoid returning VM_FAULT_RETRY from ->page_mkwrite handlers
Date: Fri, 3 Feb 2017 15:20:54 -0800 [thread overview]
Message-ID: <20170203152054.6ee9f8a920e6d0ac8a93d2b9@linux-foundation.org> (raw)
In-Reply-To: <20170203150729.15863-1-jack@suse.cz>
On Fri, 3 Feb 2017 16:07:29 +0100 Jan Kara <jack@suse.cz> wrote:
> Some ->page_mkwrite handlers may return VM_FAULT_RETRY as its return
> code (GFS2 or Lustre can definitely do this). However VM_FAULT_RETRY
> from ->page_mkwrite is completely unhandled by the mm code and results
> in locking and writeably mapping the page which definitely is not what
> the caller wanted. Fix Lustre and block_page_mkwrite_ret() used by other
> filesystems (notably GFS2) to return VM_FAULT_NOPAGE instead which
> results in bailing out from the fault code, the CPU then retries the
> access, and we fault again effectively doing what the handler wanted.
I'm not getting any sense of the urgency of this fix. The bug *sounds*
bad? Which kernel versions need fixing?
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next prev parent reply other threads:[~2017-02-03 23:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-03 15:07 [PATCH] mm: Avoid returning VM_FAULT_RETRY from ->page_mkwrite handlers Jan Kara
2017-02-03 15:13 ` Matthew Wilcox
2017-02-03 15:46 ` Jan Kara
2017-02-03 15:53 ` Matthew Wilcox
2017-02-03 16:10 ` Jan Kara
2017-02-03 23:20 ` Andrew Morton [this message]
2017-02-06 9:24 ` Jan Kara
2017-02-03 23:44 ` [lustre-devel] " Xiong, Jinshan
2017-02-06 8:59 ` Jan Kara
2017-02-06 20:52 ` Xiong, Jinshan
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