From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f41.google.com (mail-pa0-f41.google.com [209.85.220.41]) by kanga.kvack.org (Postfix) with ESMTP id 52634900003 for ; Wed, 9 Jul 2014 02:37:12 -0400 (EDT) Received: by mail-pa0-f41.google.com with SMTP id fb1so8684467pad.28 for ; Tue, 08 Jul 2014 23:37:12 -0700 (PDT) Received: from mail-pd0-x234.google.com (mail-pd0-x234.google.com [2607:f8b0:400e:c02::234]) by mx.google.com with ESMTPS id zo4si45225120pbc.242.2014.07.08.23.37.10 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 08 Jul 2014 23:37:10 -0700 (PDT) Received: by mail-pd0-f180.google.com with SMTP id fp1so8483183pdb.39 for ; Tue, 08 Jul 2014 23:37:10 -0700 (PDT) Date: Tue, 8 Jul 2014 23:35:32 -0700 (PDT) From: Hugh Dickins Subject: Re: + shmem-fix-faulting-into-a-hole-while-its-punched-take-2.patch added to -mm tree In-Reply-To: <53BCBF1F.1000506@oracle.com> Message-ID: References: <53b45c9b.2rlA0uGYBLzlXEeS%akpm@linux-foundation.org> <53BCBF1F.1000506@oracle.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: akpm@linux-foundation.org, hughd@google.com, davej@redhat.com, koct9i@gmail.com, lczerner@redhat.com, stable@vger.kernel.org, Vlastimil Babka , "linux-mm@kvack.org" , LKML On Wed, 9 Jul 2014, Sasha Levin wrote: > On 07/02/2014 03:25 PM, akpm@linux-foundation.org wrote: > > From: Hugh Dickins > > Subject: shmem: fix faulting into a hole while it's punched, take 2 > > I suspect there's something off with this patch, as the shmem_fallocate > hangs are back... Pretty much same as before: Thank you for reporting, but that is depressing news. I don't see what's wrong with this (take 2) patch, and I don't see that it's been garbled in any way in next-20140708. > > [ 363.600969] INFO: task trinity-c327:9203 blocked for more than 120 seconds. > [ 363.605359] Not tainted 3.16.0-rc4-next-20140708-sasha-00022-g94c7290-dirty #772 > [ 363.609730] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 363.615861] trinity-c327 D 000000000000000b 13496 9203 8559 0x10000004 > [ 363.620284] ffff8800b857bce8 0000000000000002 ffffffff9dc11b10 0000000000000001 > [ 363.624468] ffff880104860000 ffff8800b857bfd8 00000000001d7740 00000000001d7740 > [ 363.629118] ffff880104863000 ffff880104860000 ffff8800b857bcd8 ffff8801eaed8868 > [ 363.633879] Call Trace: > [ 363.635442] [] schedule+0x65/0x70 > [ 363.638638] [] schedule_preempt_disabled+0x18/0x30 > [ 363.642833] [] mutex_lock_nested+0x2e5/0x550 > [ 363.646599] [] ? shmem_fallocate+0x6c/0x350 > [ 363.651319] [] ? get_parent_ip+0x11/0x50 > [ 363.654683] [] ? shmem_fallocate+0x6c/0x350 > [ 363.658264] [] shmem_fallocate+0x6c/0x350 So it's trying to acquire i_mutex at shmem_fallocate+0x6c... > [ 363.662010] [] ? put_lock_stats.isra.12+0xe/0x30 > [ 363.665866] [] do_fallocate+0x153/0x1d0 > [ 363.669381] [] SyS_madvise+0x33f/0x970 > [ 363.672906] [] tracesys+0xe1/0xe6 > [ 363.682900] 2 locks held by trinity-c327/9203: > [ 363.684928] #0: (sb_writers#12){.+.+.+}, at: [] do_fallocate+0x13d/0x1d0 > [ 363.715102] #1: (&sb->s_type->i_mutex_key#16){+.+.+.}, at: [] shmem_fallocate+0x6c/0x350 ...but it already holds i_mutex, acquired at shmem_fallocate+0x6c. Am I reading that correctly? In my source for next-20140708, the only return from shmem_fallocate() which omits to mutex_unlock(&inode->i_mutex) is the "return -EOPNOTSUPP" at the top, just before the mutex_lock(&inode->i_mutex). And inode doesn't get reassigned in the middle. Does 3.16.0-rc4-next-20140708-sasha-00022-g94c7290-dirty look different? Hugh -- 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