From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0910.google.com with SMTP id l15so1038637rvb for ; Mon, 22 Oct 2007 13:48:37 -0700 (PDT) Message-ID: <84144f020710221348x297795c0qda61046ec69a7178@mail.gmail.com> Date: Mon, 22 Oct 2007 23:48:37 +0300 From: "Pekka Enberg" Subject: Re: msync(2) bug(?), returns AOP_WRITEPAGE_ACTIVATE to userland In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200710142232.l9EMW8kK029572@agora.fsl.cs.sunysb.edu> <84144f020710150447o94b1babo8b6e6a647828465f@mail.gmail.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: Erez Zadok , Ryan Finnie , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, cjwatson@ubuntu.com, linux-mm@kvack.org, neilb@suse.de List-ID: Hi Hugh, On Mon, 15 Oct 2007, Pekka Enberg wrote: > > I wonder whether _not setting_ BDI_CAP_NO_WRITEBACK implies that > > ->writepage() will never return AOP_WRITEPAGE_ACTIVATE for > > !wbc->for_reclaim case which would explain why we haven't hit this bug > > before. Hugh, Andrew? On 10/22/07, Hugh Dickins wrote: > Only ramdisk and shmem have been returning AOP_WRITEPAGE_ACTIVATE. > Both of those set BDI_CAP_NO_WRITEBACK. ramdisk never returned it > if !wbc->for_reclaim. I contend that shmem shouldn't either: it's > a special code to get the LRU rotation right, not useful elsewhere. > Though Documentation/filesystems/vfs.txt does imply wider use. > > I think this is where people use the phrase "go figure" ;) Heh. As far as I can tell, the implication of "wider use" was added by Neil in commit "341546f5ad6fce584531f744853a5807a140f2a9 Update some VFS documentation", so perhaps he might know? Neil? Pekka -- 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