From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 3 Feb 2017 15:20:54 -0800 From: Andrew Morton To: Jan Kara Cc: Al Viro , , , lustre-devel@lists.lustre.org, cluster-devel@redhat.com Subject: Re: [PATCH] mm: Avoid returning VM_FAULT_RETRY from ->page_mkwrite handlers Message-Id: <20170203152054.6ee9f8a920e6d0ac8a93d2b9@linux-foundation.org> In-Reply-To: <20170203150729.15863-1-jack@suse.cz> References: <20170203150729.15863-1-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: On Fri, 3 Feb 2017 16:07:29 +0100 Jan Kara 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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org