> ----- Original Message ----- > > From: "Al Viro" <viro@xxxxxxxxxxxxxxxxxx> > > To: "CAI Qian" <caiqian@xxxxxxxxxx> > > Cc: "Linus Torvalds" <torvalds@xxxxxxxxxxxxxxxxxxxx>, "Dave Chinner" > > <david@xxxxxxxxxxxxx>, "linux-xfs" > > <linux-xfs@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, "Jens Axboe" > > <axboe@xxxxxxxxx>, "Nick Piggin" <npiggin@xxxxxxxxx>, > > linux-fsdevel@xxxxxxxxxxxxxxx > > Sent: Sunday, October 2, 2016 9:37:37 PM > > Subject: Re: [RFC][CFT] splice_read reworked > > > > On Fri, Sep 30, 2016 at 02:33:23PM -0400, CAI Qian wrote: > > > > OK, the immeditate trigger is > > * sendfile() from something that uses seq_read to a regular file. > > Does sb_start_write() around the call of do_splice_direct() (as always), > > which ends up calling default_file_splice_read() (again, as usual), which > > ends up calling ->read() of the source, i.e. seq_read(). No changes there. > > > > * sb_start_write() can be called under ->i_mutex. The latter is > > on overlayfs inode, the former is done to upper layer in that overlayfs. > > Nothing new, again. > > > > * ->i_mutex can be taken under ->cred_guard_mutex. Yes, it can - > > in open_exec(). Again, no changes. > > > > * ->cred_guard_mutex can be taken in ->show() of a seq_file, > > namely /proc/*/auxv... Argh, ->cred_guard_mutex whack-a-mole strikes > > again... > > > > OK, I think essentially the same warning had been triggerable since _way_ > > back. All changes around splice have no effect on it. > > > > Look: to get a deadlock we need > > (1) sendfile from /proc/<pid>/auxv to a regular file on upper layer of > > overlayfs requesting not to freeze the target. > > (2) attempt to freeze it blocking until (1) is done. > > (3) directory modification on overlayfs trying to request not to freeze > > the upper layer and blocking until (2) is done. > > (4) execve() in <pid> holding ->cred_guard_mutex, trying to open > > something in overlayfs and getting blocked on directory lock, held by (3). > > > > Now (1) gets around to reading from /proc/<pid>/auxv, which blocks on > > ->cred_guard_mutex. Mentioning of seq_read itself holding locks is > > irrelevant; > > what matters is that ->read() grabs ->cred_guard_mutex. > > > > We used to have similar problems in /proc/*/environ and /proc/*/mem; looks > > like /proc/*/environ needs to get the treatment similar to e268337dfe26 and > > b409e578d9a4. > > > You are right. This is also reproducible on v4.8 mainline. Not sure if related, but right after this lockdep happened and trinity running by a non-privileged user finished inside the container. The host's systemctl command just hang or timeout which renders the whole system unusable. # systemctl status docker Failed to get properties: Connection timed out # systemctl reboot (hang) [ 5535.596651] INFO: task systemd-journal:1165 blocked for more than 120 seconds. [ 5535.604728] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5535.611536] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5535.620285] systemd-journal D ffff880466167ca8 12672 1165 1 0x00000000 [ 5535.628182] ffff880466167ca8 ffff880466167cd0 0000000000000000 ffff88086c6e2000 [ 5535.636504] ffff88045deb0000 ffff880466168000 ffffffff81deb380 ffff88045deb0000 [ 5535.644817] 0000000000000246 00000000ffffffff ffff880466167cc0 ffffffff817cdaaf [ 5535.653131] Call Trace: [ 5535.655874] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5535.661425] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5535.668617] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5535.675237] [<ffffffff81161d7e>] ? proc_cgroup_show+0x4e/0x300 [ 5535.681857] [<ffffffff81252b01>] ? kmem_cache_alloc_trace+0x1d1/0x2e0 [ 5535.689162] [<ffffffff81161d7e>] proc_cgroup_show+0x4e/0x300 [ 5535.695592] [<ffffffff81302d40>] proc_single_show+0x50/0x90 [ 5535.701925] [<ffffffff812ac983>] seq_read+0x113/0x3e0 [ 5535.707672] [<ffffffff81280407>] __vfs_read+0x37/0x150 [ 5535.713521] [<ffffffff81349ded>] ? security_file_permission+0x9d/0xc0 [ 5535.720819] [<ffffffff812815ac>] vfs_read+0x8c/0x130 [ 5535.726472] [<ffffffff81282ac8>] SyS_read+0x58/0xc0 [ 5535.732024] [<ffffffff817d497c>] entry_SYSCALL_64_fastpath+0x1f/0xbd [ 5535.739221] INFO: lockdep is turned off. [ 5535.743649] INFO: task kworker/3:1:52401 blocked for more than 120 seconds. [ 5535.751429] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5535.758239] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5535.766989] kworker/3:1 D ffff8803b25bbca8 13368 52401 2 0x00000080 [ 5535.774904] Workqueue: cgroup_destroy css_release_work_fn [ 5535.780940] ffff8803b25bbca8 ffff8803b25bbcd0 0000000000000000 ffff88046ded2000 [ 5535.789254] ffff88046af8a000 ffff8803b25bc000 ffffffff81deb380 ffff88046af8a000 [ 5535.797562] 0000000000000246 00000000ffffffff ffff8803b25bbcc0 ffffffff817cdaaf [ 5535.805877] Call Trace: [ 5535.808621] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5535.814177] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5535.821379] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5535.828001] [<ffffffff811586af>] ? css_release_work_fn+0x2f/0x110 [ 5535.834911] [<ffffffff811586af>] css_release_work_fn+0x2f/0x110 [ 5535.841629] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5535.848159] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5535.854876] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5535.861119] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5535.867847] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5535.873404] [<ffffffff817d40ec>] ? _raw_spin_unlock_irq+0x2c/0x60 [ 5535.880320] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5535.886369] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 [ 5535.893675] INFO: lockdep is turned off. [ 5535.898085] INFO: task kworker/45:4:146035 blocked for more than 120 seconds. [ 5535.906059] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5535.912865] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5535.921613] kworker/45:4 D ffff880853e9b950 14048 146035 2 0x00000080 [ 5535.929630] Workqueue: cgroup_destroy css_killed_work_fn [ 5535.935582] ffff880853e9b950 0000000000000000 0000000000000000 ffff88086c6da000 [ 5535.943882] ffff88086c9e2000 ffff880853e9c000 ffff880853e9baa0 ffff88086c9e2000 [ 5535.952205] ffff880853e9ba98 0000000000000001 ffff880853e9b968 ffffffff817cdaaf [ 5535.960522] Call Trace: [ 5535.963265] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5535.968817] [<ffffffff817d33fb>] schedule_timeout+0x3db/0x6f0 [ 5535.975346] [<ffffffff817cf055>] ? wait_for_completion+0x45/0x130 [ 5535.982256] [<ffffffff817cf0d3>] wait_for_completion+0xc3/0x130 [ 5535.988972] [<ffffffff810d1fd0>] ? wake_up_q+0x80/0x80 [ 5535.994804] [<ffffffff8130de64>] drop_sysctl_table+0xc4/0xe0 [ 5536.001227] [<ffffffff8130de17>] drop_sysctl_table+0x77/0xe0 [ 5536.007648] [<ffffffff8130decd>] unregister_sysctl_table+0x4d/0xa0 [ 5536.014654] [<ffffffff8130deff>] unregister_sysctl_table+0x7f/0xa0 [ 5536.021657] [<ffffffff810f57f5>] unregister_sched_domain_sysctl+0x15/0x40 [ 5536.029344] [<ffffffff810d7704>] partition_sched_domains+0x44/0x450 [ 5536.036447] [<ffffffff817d0761>] ? __mutex_unlock_slowpath+0x111/0x1f0 [ 5536.043844] [<ffffffff81167684>] rebuild_sched_domains_locked+0x64/0xb0 [ 5536.051336] [<ffffffff8116789d>] update_flag+0x11d/0x210 [ 5536.057373] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5536.064186] [<ffffffff81167acb>] ? cpuset_css_offline+0x1b/0x60 [ 5536.070899] [<ffffffff810fce3d>] ? trace_hardirqs_on+0xd/0x10 [ 5536.077420] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5536.084234] [<ffffffff8115a9f5>] ? css_killed_work_fn+0x25/0x220 [ 5536.091049] [<ffffffff81167ae5>] cpuset_css_offline+0x35/0x60 [ 5536.097571] [<ffffffff8115aa2c>] css_killed_work_fn+0x5c/0x220 [ 5536.104207] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5536.110736] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5536.117461] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5536.123697] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5536.130426] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5536.135991] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5536.142041] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 [ 5536.149345] INFO: lockdep is turned off. [ 5585.148183] perf: interrupt took too long (3146 > 3136), lowering kernel.perf_event_max_sample_rate to 63000 [ 5658.479538] INFO: task systemd:1 blocked for more than 120 seconds. [ 5658.486551] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5658.493352] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5658.502095] systemd D ffff880468ccfca8 11952 1 0 0x00000000 [ 5658.509995] ffff880468ccfca8 ffff880468ccfcd0 0000000000000000 ffff88046aa24000 [ 5658.518297] ffff880468cd0000 ffff880468cd0000 ffffffff81deb380 ffff880468cd0000 [ 5658.526602] 0000000000000246 00000000ffffffff ffff880468ccfcc0 ffffffff817cdaaf [ 5658.534909] Call Trace: [ 5658.537645] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5658.543188] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5658.550375] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5658.556987] [<ffffffff81161d7e>] ? proc_cgroup_show+0x4e/0x300 [ 5658.563600] [<ffffffff81252b01>] ? kmem_cache_alloc_trace+0x1d1/0x2e0 [ 5658.570887] [<ffffffff81161d7e>] proc_cgroup_show+0x4e/0x300 [ 5658.577304] [<ffffffff81302d40>] proc_single_show+0x50/0x90 [ 5658.583620] [<ffffffff812ac983>] seq_read+0x113/0x3e0 [ 5658.589355] [<ffffffff81280407>] __vfs_read+0x37/0x150 [ 5658.595189] [<ffffffff81349ded>] ? security_file_permission+0x9d/0xc0 [ 5658.602480] [<ffffffff812815ac>] vfs_read+0x8c/0x130 [ 5658.608117] [<ffffffff81282ac8>] SyS_read+0x58/0xc0 [ 5658.613661] [<ffffffff817d497c>] entry_SYSCALL_64_fastpath+0x1f/0xbd [ 5658.620849] INFO: lockdep is turned off. [ 5658.625282] INFO: task systemd-journal:1165 blocked for more than 120 seconds. [ 5658.633346] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5658.640147] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5658.648887] systemd-journal D ffff880466167ca8 12672 1165 1 0x00000000 [ 5658.656788] ffff880466167ca8 ffff880466167cd0 0000000000000000 ffff88086c6e2000 [ 5658.665092] ffff88045deb0000 ffff880466168000 ffffffff81deb380 ffff88045deb0000 [ 5658.673394] 0000000000000246 00000000ffffffff ffff880466167cc0 ffffffff817cdaaf [ 5658.681690] Call Trace: [ 5658.684419] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5658.689961] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5658.697143] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5658.703766] [<ffffffff81161d7e>] ? proc_cgroup_show+0x4e/0x300 [ 5658.710373] [<ffffffff81252b01>] ? kmem_cache_alloc_trace+0x1d1/0x2e0 [ 5658.717661] [<ffffffff81161d7e>] proc_cgroup_show+0x4e/0x300 [ 5658.724067] [<ffffffff81302d40>] proc_single_show+0x50/0x90 [ 5658.730386] [<ffffffff812ac983>] seq_read+0x113/0x3e0 [ 5658.736123] [<ffffffff81280407>] __vfs_read+0x37/0x150 [ 5658.741957] [<ffffffff81349ded>] ? security_file_permission+0x9d/0xc0 [ 5658.749244] [<ffffffff812815ac>] vfs_read+0x8c/0x130 [ 5658.754884] [<ffffffff81282ac8>] SyS_read+0x58/0xc0 [ 5658.760417] [<ffffffff817d497c>] entry_SYSCALL_64_fastpath+0x1f/0xbd [ 5658.767607] INFO: lockdep is turned off. [ 5658.772016] INFO: task kworker/3:1:52401 blocked for more than 120 seconds. [ 5658.779789] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5658.786582] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5658.795322] kworker/3:1 D ffff8803b25bbca8 13368 52401 2 0x00000080 [ 5658.803224] Workqueue: cgroup_destroy css_release_work_fn [ 5658.809261] ffff8803b25bbca8 ffff8803b25bbcd0 0000000000000000 ffff88046ded2000 [ 5658.817567] ffff88046af8a000 ffff8803b25bc000 ffffffff81deb380 ffff88046af8a000 [ 5658.825871] 0000000000000246 00000000ffffffff ffff8803b25bbcc0 ffffffff817cdaaf [ 5658.834173] Call Trace: [ 5658.836904] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5658.842447] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5658.849638] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5658.856246] [<ffffffff811586af>] ? css_release_work_fn+0x2f/0x110 [ 5658.863146] [<ffffffff811586af>] css_release_work_fn+0x2f/0x110 [ 5658.869858] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5658.876370] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5658.883067] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5658.889287] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5658.895991] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5658.901538] [<ffffffff817d40ec>] ? _raw_spin_unlock_irq+0x2c/0x60 [ 5658.908438] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5658.914466] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 [ 5658.921745] INFO: lockdep is turned off. [ 5658.926133] INFO: task kworker/45:4:146035 blocked for more than 120 seconds. [ 5658.934099] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5658.940902] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5658.949636] kworker/45:4 D ffff880853e9b950 14048 146035 2 0x00000080 [ 5658.957632] Workqueue: cgroup_destroy css_killed_work_fn [ 5658.963574] ffff880853e9b950 0000000000000000 0000000000000000 ffff88086c6da000 [ 5658.971877] ffff88086c9e2000 ffff880853e9c000 ffff880853e9baa0 ffff88086c9e2000 [ 5658.980179] ffff880853e9ba98 0000000000000001 ffff880853e9b968 ffffffff817cdaaf [ 5658.988498] Call Trace: [ 5658.991225] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5658.996768] [<ffffffff817d33fb>] schedule_timeout+0x3db/0x6f0 [ 5659.003271] [<ffffffff817cf055>] ? wait_for_completion+0x45/0x130 [ 5659.010161] [<ffffffff817cf0d3>] wait_for_completion+0xc3/0x130 [ 5659.016871] [<ffffffff810d1fd0>] ? wake_up_q+0x80/0x80 [ 5659.022706] [<ffffffff8130de64>] drop_sysctl_table+0xc4/0xe0 [ 5659.029120] [<ffffffff8130de17>] drop_sysctl_table+0x77/0xe0 [ 5659.035535] [<ffffffff8130decd>] unregister_sysctl_table+0x4d/0xa0 [ 5659.042529] [<ffffffff8130deff>] unregister_sysctl_table+0x7f/0xa0 [ 5659.049528] [<ffffffff810f57f5>] unregister_sched_domain_sysctl+0x15/0x40 [ 5659.057203] [<ffffffff810d7704>] partition_sched_domains+0x44/0x450 [ 5659.064297] [<ffffffff817d0761>] ? __mutex_unlock_slowpath+0x111/0x1f0 [ 5659.071673] [<ffffffff81167684>] rebuild_sched_domains_locked+0x64/0xb0 [ 5659.079144] [<ffffffff8116789d>] update_flag+0x11d/0x210 [ 5659.085172] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5659.091964] [<ffffffff81167acb>] ? cpuset_css_offline+0x1b/0x60 [ 5659.098668] [<ffffffff810fce3d>] ? trace_hardirqs_on+0xd/0x10 [ 5659.105179] [<ffffffff817cf61f>] ? mutex_lock_nested+0x2df/0x450 [ 5659.111982] [<ffffffff8115a9f5>] ? css_killed_work_fn+0x25/0x220 [ 5659.118783] [<ffffffff81167ae5>] cpuset_css_offline+0x35/0x60 [ 5659.125296] [<ffffffff8115aa2c>] css_killed_work_fn+0x5c/0x220 [ 5659.131906] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5659.138417] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5659.145124] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5659.151345] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5659.158044] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5659.163586] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5659.169605] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 [ 5659.176892] INFO: lockdep is turned off. [ 5781.364367] INFO: task systemd:1 blocked for more than 120 seconds. [ 5781.371373] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5781.378177] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5781.386918] systemd D ffff880468ccfca8 11952 1 0 0x00000000 [ 5781.394818] ffff880468ccfca8 ffff880468ccfcd0 0000000000000000 ffff88046aa24000 [ 5781.403121] ffff880468cd0000 ffff880468cd0000 ffffffff81deb380 ffff880468cd0000 [ 5781.411421] 0000000000000246 00000000ffffffff ffff880468ccfcc0 ffffffff817cdaaf [ 5781.419725] Call Trace: [ 5781.422460] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5781.428003] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5781.435192] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5781.441801] [<ffffffff81161d7e>] ? proc_cgroup_show+0x4e/0x300 [ 5781.448404] [<ffffffff81252b01>] ? kmem_cache_alloc_trace+0x1d1/0x2e0 [ 5781.455691] [<ffffffff81161d7e>] proc_cgroup_show+0x4e/0x300 [ 5781.462109] [<ffffffff81302d40>] proc_single_show+0x50/0x90 [ 5781.468428] [<ffffffff812ac983>] seq_read+0x113/0x3e0 [ 5781.474165] [<ffffffff81280407>] __vfs_read+0x37/0x150 [ 5781.479991] [<ffffffff81349ded>] ? security_file_permission+0x9d/0xc0 [ 5781.487277] [<ffffffff812815ac>] vfs_read+0x8c/0x130 [ 5781.492914] [<ffffffff81282ac8>] SyS_read+0x58/0xc0 [ 5781.498455] [<ffffffff817d497c>] entry_SYSCALL_64_fastpath+0x1f/0xbd [ 5781.505646] INFO: lockdep is turned off. [ 5781.510085] INFO: task systemd-journal:1165 blocked for more than 120 seconds. [ 5781.518146] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5781.524946] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5781.533686] systemd-journal D ffff880466167ca8 12672 1165 1 0x00000000 [ 5781.541581] ffff880466167ca8 ffff880466167cd0 0000000000000000 ffff88086c6e2000 [ 5781.549880] ffff88045deb0000 ffff880466168000 ffffffff81deb380 ffff88045deb0000 [ 5781.558186] 0000000000000246 00000000ffffffff ffff880466167cc0 ffffffff817cdaaf [ 5781.566493] Call Trace: [ 5781.569222] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5781.574764] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5781.581953] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5781.588559] [<ffffffff81161d7e>] ? proc_cgroup_show+0x4e/0x300 [ 5781.595166] [<ffffffff81252b01>] ? kmem_cache_alloc_trace+0x1d1/0x2e0 [ 5781.602451] [<ffffffff81161d7e>] proc_cgroup_show+0x4e/0x300 [ 5781.608864] [<ffffffff81302d40>] proc_single_show+0x50/0x90 [ 5781.615182] [<ffffffff812ac983>] seq_read+0x113/0x3e0 [ 5781.620916] [<ffffffff81280407>] __vfs_read+0x37/0x150 [ 5781.626749] [<ffffffff81349ded>] ? security_file_permission+0x9d/0xc0 [ 5781.634035] [<ffffffff812815ac>] vfs_read+0x8c/0x130 [ 5781.639673] [<ffffffff81282ac8>] SyS_read+0x58/0xc0 [ 5781.645215] [<ffffffff817d497c>] entry_SYSCALL_64_fastpath+0x1f/0xbd [ 5781.652403] INFO: lockdep is turned off. [ 5781.656811] INFO: task kworker/3:1:52401 blocked for more than 120 seconds. [ 5781.664583] Tainted: G W 4.8.0-rc8-fornext+ #1 [ 5781.671383] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5781.680121] kworker/3:1 D ffff8803b25bbca8 13368 52401 2 0x00000080 [ 5781.688021] Workqueue: cgroup_destroy css_release_work_fn [ 5781.694057] ffff8803b25bbca8 ffff8803b25bbcd0 0000000000000000 ffff88046ded2000 [ 5781.702356] ffff88046af8a000 ffff8803b25bc000 ffffffff81deb380 ffff88046af8a000 [ 5781.710656] 0000000000000246 00000000ffffffff ffff8803b25bbcc0 ffffffff817cdaaf [ 5781.718954] Call Trace: [ 5781.721684] [<ffffffff817cdaaf>] schedule+0x3f/0xa0 [ 5781.727224] [<ffffffff817cdf18>] schedule_preempt_disabled+0x18/0x30 [ 5781.734414] [<ffffffff817cf4df>] mutex_lock_nested+0x19f/0x450 [ 5781.741021] [<ffffffff811586af>] ? css_release_work_fn+0x2f/0x110 [ 5781.747919] [<ffffffff811586af>] css_release_work_fn+0x2f/0x110 [ 5781.754626] [<ffffffff810bc83f>] process_one_work+0x1df/0x710 [ 5781.761137] [<ffffffff810bc7c0>] ? process_one_work+0x160/0x710 [ 5781.767841] [<ffffffff810bce9b>] worker_thread+0x12b/0x4a0 [ 5781.774061] [<ffffffff810bcd70>] ? process_one_work+0x710/0x710 [ 5781.780765] [<ffffffff810c3f7e>] kthread+0xfe/0x120 [ 5781.786304] [<ffffffff817d40ec>] ? _raw_spin_unlock_irq+0x2c/0x60 [ 5781.793203] [<ffffffff817d4baf>] ret_from_fork+0x1f/0x40 [ 5781.799229] [<ffffffff810c3e80>] ? kthread_create_on_node+0x230/0x230 [ 5781.806514] INFO: lockdep is turned off. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
