From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by nz-out-0506.google.com with SMTP id s1so961992nze for ; Mon, 15 Oct 2007 04:47:53 -0700 (PDT) Message-ID: <84144f020710150447o94b1babo8b6e6a647828465f@mail.gmail.com> Date: Mon, 15 Oct 2007 14:47:52 +0300 From: "Pekka Enberg" Subject: Re: msync(2) bug(?), returns AOP_WRITEPAGE_ACTIVATE to userland In-Reply-To: <200710142232.l9EMW8kK029572@agora.fsl.cs.sunysb.edu> 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> Sender: owner-linux-mm@kvack.org Return-Path: To: Erez Zadok Cc: Hugh Dickins , Ryan Finnie , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, cjwatson@ubuntu.com, linux-mm@kvack.org List-ID: Hi, On 10/15/07, Erez Zadok wrote: > Pekka, with a small change to your patch (to handle time-based cache > coherency), your patch worked well and passed all my tests. Thanks. > > So now I wonder if we still need the patch to prevent AOP_WRITEPAGE_ACTIVATE > from being returned to userland. I guess we still need it, b/c even with > your patch, generic_writepages() can return AOP_WRITEPAGE_ACTIVATE back to > the VFS and we need to ensure that doesn't "leak" outside the kernel. 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? And btw, I think we need to fix ecryptfs too. 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