From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e5.ny.us.ibm.com (8.13.8/8.12.11) with ESMTP id kAFIKmYI007219 for ; Wed, 15 Nov 2006 13:20:48 -0500 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.6/8.13.6/NCO v8.1.1) with ESMTP id kAFIKkQn250160 for ; Wed, 15 Nov 2006 13:20:46 -0500 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id kAFIKjsu022141 for ; Wed, 15 Nov 2006 13:20:45 -0500 Message-ID: <455B5A7B.6010807@us.ibm.com> Date: Wed, 15 Nov 2006 10:20:43 -0800 From: Badari Pulavarty MIME-Version: 1.0 Subject: Re: pagefault in generic_file_buffered_write() causing deadlock References: <1163606265.7662.8.camel@dyn9047017100.beaverton.ibm.com> <20061115090005.c9ec6db5.akpm@osdl.org> In-Reply-To: <20061115090005.c9ec6db5.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-mm , ext4 , lkml List-ID: Andrew Morton wrote: > On Wed, 15 Nov 2006 07:57:45 -0800 > Badari Pulavarty wrote: > > >> We are looking at a customer situation (on 2.6.16-based distro) - where >> system becomes almost useless while running some java & stress tests. >> >> Root cause seems to be taking a pagefault in generic_file_buffered_write >> () after calling prepare_write. I am wondering >> >> 1) Why & How this can happen - since we made sure to fault the user >> buffer before prepare write. >> > > When using writev() we only fault in the first segment of the iovec. If > the second or succesive segment isn't mapped into pagetables we're > vulnerable to the deadlock. > > Hmm.. Not it :( Its coming from write() not writev(). [C00000002ABBF290] [C00000000039D58C] .do_page_fault+0x2e4/0x75c [C00000002ABBF460] [C000000000004860] .handle_page_fault+0x20/0x54 --- Exception: 301 at .__copy_tofrom_user+0x11c/0x580 LR = .generic_file_buffered_write+0x39c/0x7c8 [C00000002ABBF750] [C000000000095A94] .generic_file_buffered_write+0x2c0/0x7c8 ( unreliable) [C00000002ABBF8F0] [C0000000000962EC] .__generic_file_aio_write_nolock+0x350/0x3 e0 [C00000002ABBFA20] [C000000000096908] .generic_file_aio_write+0x78/0x104 [C00000002ABBFAE0] [C0000000001649F0] .ext3_file_write+0x2c/0xd4 [C00000002ABBFB70] [C0000000000C5168] .do_sync_write+0xd4/0x130 [C00000002ABBFCF0] [C0000000000C5ED4] .vfs_write+0x128/0x20c [C00000002ABBFD90] [C0000000000C664C] .sys_write+0x4c/0x8c [C00000002ABBFE30] [C00000000000871C] syscall_exit+0x0/0x40 Thanks, Badari -- 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