From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx5-phx2.redhat.com ([209.132.183.37]:60979 "EHLO mx5-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932348AbcI3Sdc (ORCPT ); Fri, 30 Sep 2016 14:33:32 -0400 Date: Fri, 30 Sep 2016 14:33:23 -0400 (EDT) From: CAI Qian To: Al Viro Cc: Linus Torvalds , Dave Chinner , linux-xfs , xfs@oss.sgi.com, Jens Axboe , Nick Piggin , linux-fsdevel@vger.kernel.org Message-ID: <774397084.821469.1475260403929.JavaMail.zimbra@redhat.com> In-Reply-To: <1415238593.811146.1475257337058.JavaMail.zimbra@redhat.com> References:

<20160914042559.GC2356@ZenIV.linux.org.uk> <20160917082007.GA6489@ZenIV.linux.org.uk> <20160917190023.GA8039@ZenIV.linux.org.uk> <20160923190032.GA25771@ZenIV.linux.org.uk> <2131586457.763354.1475242373422.JavaMail.zimbra@redhat.com> <1415238593.811146.1475257337058.JavaMail.zimbra@redhat.com> Subject: Re: [RFC][CFT] splice_read reworked MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: ----- Original Message ----- > One warning just pop up while running trinity. Another run triggered a lockdep with splice in the trace, [ 4787.875980] [ 4787.877645] ====================================================== [ 4787.884540] [ INFO: possible circular locking dependency detected ] [ 4787.891533] 4.8.0-rc8-usrns-scale+ #8 Tainted: G W [ 4787.898138] ------------------------------------------------------- [ 4787.905130] trinity-c116/106905 is trying to acquire lock: [ 4787.911251] (&p->lock){+.+.+.}, at: [] seq_read+0x4c/0x3e0 [ 4787.919264] [ 4787.919264] but task is already holding lock: [ 4787.925773] (sb_writers#8){.+.+.+}, at: [] __sb_start_write+0xb7/0xf0 [ 4787.934854] [ 4787.934854] which lock already depends on the new lock. [ 4787.934854] [ 4787.943981] [ 4787.943981] the existing dependency chain (in reverse order) is: [ 4787.952333] -> #3 (sb_writers#8){.+.+.+}: [ 4787.957050] [] __lock_acquire+0x3f1/0x7f0 [ 4787.963960] [] lock_acquire+0xd6/0x240 [ 4787.970577] [] percpu_down_read+0x4a/0xa0 [ 4787.977487] [] __sb_start_write+0xb7/0xf0 [ 4787.984395] [] mnt_want_write+0x24/0x50 [ 4787.991110] [] ovl_want_write+0x1f/0x30 [overlay] [ 4787.998799] [] ovl_do_remove+0x42/0x4a0 [overlay] [ 4788.006483] [] ovl_rmdir+0x16/0x20 [overlay] [ 4788.013682] [] vfs_rmdir+0xb7/0x130 [ 4788.020009] [] do_rmdir+0x183/0x1f0 [ 4788.026335] [] SyS_unlinkat+0x22/0x30 [ 4788.032853] [] do_syscall_64+0x6c/0x1e0 [ 4788.039576] [] return_from_SYSCALL_64+0x0/0x7a [ 4788.046962] -> #2 (&sb->s_type->i_mutex_key#16){++++++}: [ 4788.053140] [] __lock_acquire+0x3f1/0x7f0 [ 4788.060049] [] lock_acquire+0xd6/0x240 [ 4788.066664] [] down_read+0x47/0x70 [ 4788.072893] [] lookup_slow+0xc9/0x200 [ 4788.079410] [] walk_component+0x1ec/0x310 [ 4788.086315] [] link_path_walk+0x19f/0x5f0 [ 4788.093219] [] path_openat+0xdd/0xb80 [ 4788.099748] [] do_filp_open+0x91/0x100 [ 4788.106362] [] do_open_execat+0x76/0x180 [ 4788.113186] [] open_exec+0x2b/0x50 [ 4788.119404] [] load_elf_binary+0x28d/0x1120 [ 4788.126511] [] search_binary_handler+0x97/0x1c0 [ 4788.134002] [] do_execveat_common.isra.36+0x6a9/0x9f0 [ 4788.142071] [] SyS_execve+0x3a/0x50 [ 4788.148398] [] do_syscall_64+0x6c/0x1e0 [ 4788.155110] [] return_from_SYSCALL_64+0x0/0x7a [ 4788.162502] -> #1 (&sig->cred_guard_mutex){+.+.+.}: [ 4788.168179] [] __lock_acquire+0x3f1/0x7f0 [ 4788.175085] [] lock_acquire+0xd6/0x240 [ 4788.181712] [] mutex_lock_killable_nested+0x87/0x500 [ 4788.189695] [] mm_access+0x29/0xa0 [ 4788.195924] [] proc_pid_auxv+0x1c/0x70 [ 4788.202540] [] proc_single_show+0x50/0x90 [ 4788.209445] [] seq_read+0x108/0x3e0 [ 4788.215774] [] __vfs_read+0x37/0x150 [ 4788.222198] [] vfs_read+0x95/0x140 [ 4788.228425] [] SyS_read+0x58/0xc0 [ 4788.234557] [] do_syscall_64+0x6c/0x1e0 [ 4788.241268] [] return_from_SYSCALL_64+0x0/0x7a [ 4788.248660] -> #0 (&p->lock){+.+.+.}: [ 4788.252987] [] validate_chain.isra.37+0xe72/0x1150 [ 4788.260769] [] __lock_acquire+0x3f1/0x7f0 [ 4788.267676] [] lock_acquire+0xd6/0x240 [ 4788.274302] [] mutex_lock_nested+0x77/0x430 [ 4788.281406] [] seq_read+0x4c/0x3e0 [ 4788.287633] [] kernfs_fop_read+0x129/0x1b0 [ 4788.294659] [] do_loop_readv_writev+0x83/0xc0 [ 4788.301954] [] do_readv_writev+0x218/0x240 [ 4788.308959] [] vfs_readv+0x39/0x50 [ 4788.315188] [] default_file_splice_read+0x1a1/0x2b0 [ 4788.323070] [] do_splice_to+0x76/0x90 [ 4788.329587] [] splice_direct_to_actor+0xbb/0x220 [ 4788.337173] [] do_splice_direct+0x98/0xd0 [ 4788.344078] [] do_sendfile+0x1d1/0x3b0 [ 4788.350694] [] SyS_sendfile64+0xc9/0xd0 [ 4788.357405] [] do_syscall_64+0x6c/0x1e0 [ 4788.364119] [] return_from_SYSCALL_64+0x0/0x7a [ 4788.371511] [ 4788.371511] other info that might help us debug this: [ 4788.371511] [ 4788.380443] Chain exists of: &p->lock --> &sb->s_type->i_mutex_key#16 --> sb_writers#8 [ 4788.389881] Possible unsafe locking scenario: [ 4788.389881] [ 4788.396497] CPU0 CPU1 [ 4788.401549] ---- ---- [ 4788.406614] lock(sb_writers#8); [ 4788.410352] lock(&sb->s_type->i_mutex_key#16); [ 4788.418354] lock(sb_writers#8); [ 4788.424902] lock(&p->lock); [ 4788.428229] [ 4788.428229] *** DEADLOCK *** [ 4788.428229] [ 4788.434836] 1 lock held by trinity-c116/106905: [ 4788.439888] #0: (sb_writers#8){.+.+.+}, at: [] __sb_start_write+0xb7/0xf0 [ 4788.449473] [ 4788.449473] stack backtrace: [ 4788.454334] CPU: 16 PID: 106905 Comm: trinity-c116 Tainted: G W 4.8.0-rc8-usrns-scale+ #8 [ 4788.464719] Hardware name: Intel Corporation S2600WTT/S2600WTT, BIOS GRNDSDP1.86B.0044.R00.1501191641 01/19/2015 [ 4788.476076] 0000000000000086 00000000cbfc6314 ffff8803ce78b760 ffffffff813d5e93 [ 4788.484371] ffffffff82a3fbd0 ffffffff82a94890 ffff8803ce78b7a0 ffffffff810fa6ec [ 4788.492663] ffff8803ce78b7e0 ffff8802ead08000 0000000000000001 ffff8802ead08ca0 [ 4788.500966] Call Trace: [ 4788.503694] [] dump_stack+0x85/0xc2 [ 4788.509426] [] print_circular_bug+0x1ec/0x260 [ 4788.516128] [] validate_chain.isra.37+0xe72/0x1150 [ 4788.523319] [] ? ___perf_sw_event+0x171/0x290 [ 4788.530022] [] __lock_acquire+0x3f1/0x7f0 [ 4788.536335] [] lock_acquire+0xd6/0x240 [ 4788.542359] [] ? seq_read+0x4c/0x3e0 [ 4788.548188] [] ? seq_read+0x4c/0x3e0 [ 4788.554019] [] mutex_lock_nested+0x77/0x430 [ 4788.560528] [] ? seq_read+0x4c/0x3e0 [ 4788.566358] [] seq_read+0x4c/0x3e0 [ 4788.571995] [] ? kernfs_fop_open+0x3a0/0x3a0 [ 4788.578600] [] kernfs_fop_read+0x129/0x1b0 [ 4788.585012] [] ? kernfs_fop_open+0x3a0/0x3a0 [ 4788.591617] [] do_loop_readv_writev+0x83/0xc0 [ 4788.598318] [] ? kernfs_fop_open+0x3a0/0x3a0 [ 4788.604924] [] do_readv_writev+0x218/0x240 [ 4788.611347] [] ? push_pipe+0xd5/0x190 [ 4788.617278] [] ? iov_iter_get_pages_alloc+0x250/0x400 [ 4788.624746] [] vfs_readv+0x39/0x50 [ 4788.630381] [] default_file_splice_read+0x1a1/0x2b0 [ 4788.637668] [] ? security_file_permission+0xa0/0xc0 [ 4788.644954] [] do_splice_to+0x76/0x90 [ 4788.650880] [] splice_direct_to_actor+0xbb/0x220 [ 4788.657872] [] ? generic_pipe_buf_nosteal+0x10/0x10 [ 4788.665157] [] do_splice_direct+0x98/0xd0 [ 4788.671472] [] do_sendfile+0x1d1/0x3b0 [ 4788.677499] [] SyS_sendfile64+0xc9/0xd0 [ 4788.683622] [] do_syscall_64+0x6c/0x1e0 [ 4788.689744] [] entry_SYSCALL64_slow_path+0x25/0x25