On Thu, Sep 29, 2022 at 03:18:21PM +0200, Thilo Fromm wrote: > Hello Honza, > > Thank you very much for your thorough feedback. We were unaware of > the backtrace issue and will have a look at once. > > >>>So this seems like a real issue. Essentially, the problem is that > >>>ext4_bmap() acquires inode->i_rwsem while its caller > >>>jbd2_journal_flush() is holding journal->j_checkpoint_mutex. This > >>>looks like a real deadlock possibility. > >> > >>Flatcar Container Linux users have reported a kernel issue which might be > >>caused by commit 51ae846cff5. The issue is triggered under I/O load in > >>certain conditions and leads to a complete system hang. I've pasted a > >>typical kernel log below; please refer to > >>https://github.com/flatcar/Flatcar/issues/847 for more details. > >> > >>The issue can be triggered on Flatcar release 3227.2.2 / kernel version > >>5.15.63 (we ship LTS kernels) but not on release 3227.2.1 / kernel 5.15.58. > >>51ae846cff5 was introduced to 5.15 in 5.15.61. > > > >Well, so far your stacktraces do not really show anything pointing to that > >particular commit. So we need to understand that hang some more. > > This makes sense and I agree. Sorry for the garbled stack traces. > > In other news, one of our users - who can reliably trigger the issue > in their set-up - ran tests with kernel 5.15.63 with and without > commit 51ae846cff5. Without the commit, the kernel hang did not > occur (see https://github.com/flatcar/Flatcar/issues/847#issuecomment-1261967920). > > We'll now focus on un-garbling our traces to get to the bottom of this. > > >>( Kernel log of a crash follows; more info here: > >>https://github.com/flatcar/Flatcar/issues/847 ) > >> > [...] > >>[1282119.190346] ret_from_fork+0x22/0x30 > > > >Hrm, so your backtraces seem to be strange. For example in this stacktrace > >we should have kjournald2() somewhere instead of > >jbd2_journal_check_available_features() which can hardly be there. So > >somehow stack unwinding or symbol resolution is strangely confused with > >this kernel. Compiling with any unusual config or compiler? > > We're on GCC 10.3.0 and will review our build process to get to the > bottom of this. Will get back to this thread as soon as we have > news. Thanks again for pointing this out! > So our stacktraces were mangled because historically our kernel build used INSTALL_MOD_STRIP=--strip-unneeded, we've now switched it back to --strip-debug which is the default. We're still using CONFIG_UNWINDER_ORC=y. Here's the hung task output after the change to stripping: [ 1599.005306] INFO: task jbd2/sda9-8:702 blocked for more than 122 seconds. [ 1599.012290] Not tainted 5.15.63-flatcar #1 [ 1599.017128] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.025100] task:jbd2/sda9-8 state:D stack: 0 pid: 702 ppid: 2 flags:0x00004000 [ 1599.033579] Call Trace: [ 1599.036144] <TASK> [ 1599.038354] __schedule+0x2eb/0x8d0 [ 1599.042109] schedule+0x5b/0xd0 [ 1599.045372] jbd2_journal_commit_transaction+0x301/0x18e0 [jbd2] [ 1599.051518] ? wait_woken+0x70/0x70 [ 1599.055127] ? lock_timer_base+0x61/0x80 [ 1599.059181] kjournald2+0xab/0x270 [jbd2] [ 1599.063317] ? wait_woken+0x70/0x70 [ 1599.066923] ? load_superblock.part.0+0xb0/0xb0 [jbd2] [ 1599.072200] kthread+0x124/0x150 [ 1599.075543] ? set_kthread_struct+0x50/0x50 [ 1599.079849] ret_from_fork+0x1f/0x30 [ 1599.083538] </TASK> [ 1599.085835] INFO: task kworker/u32:13:732 blocked for more than 122 seconds. [ 1599.093010] Not tainted 5.15.63-flatcar #1 [ 1599.097739] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.105688] task:kworker/u32:13 state:D stack: 0 pid: 732 ppid: 2 flags:0x00004000 [ 1599.114160] Workqueue: writeback wb_workfn (flush-8:0) [ 1599.119418] Call Trace: [ 1599.121976] <TASK> [ 1599.124192] __schedule+0x2eb/0x8d0 [ 1599.127797] schedule+0x5b/0xd0 [ 1599.131051] wait_transaction_locked+0x8a/0xd0 [jbd2] [ 1599.136227] ? wait_woken+0x70/0x70 [ 1599.139829] add_transaction_credits+0xd9/0x2b0 [jbd2] [ 1599.145091] ? find_get_pages_range+0x197/0x200 [ 1599.149832] start_this_handle+0xfb/0x520 [jbd2] [ 1599.154591] ? mpage_release_unused_pages+0x1c7/0x1e0 [ext4] [ 1599.160524] ? __cond_resched+0x16/0x50 [ 1599.164478] jbd2__journal_start+0xfb/0x1e0 [jbd2] [ 1599.169393] __ext4_journal_start_sb+0xf8/0x110 [ext4] [ 1599.174669] ext4_writepages+0x302/0xfd0 [ext4] [ 1599.179328] ? __find_get_block+0xb3/0x2c0 [ 1599.183539] ? __cond_resched+0x16/0x50 [ 1599.187518] ? __getblk_gfp+0x27/0x60 [ 1599.191307] ? cpumask_next_and+0x1f/0x30 [ 1599.195433] ? update_sd_lb_stats.constprop.0+0xff/0x8a0 [ 1599.200888] do_writepages+0xce/0x200 [ 1599.204788] ? _raw_spin_unlock_irqrestore+0xa/0x30 [ 1599.209796] ? percpu_counter_add_batch+0x5b/0x70 [ 1599.214627] ? fprop_reflect_period_percpu.isra.0+0x7b/0xc0 [ 1599.220439] __writeback_single_inode+0x39/0x290 [ 1599.225183] writeback_sb_inodes+0x20d/0x490 [ 1599.229569] __writeback_inodes_wb+0x4c/0xe0 [ 1599.233951] wb_writeback+0x1c0/0x280 [ 1599.237727] wb_workfn+0x29f/0x4d0 [ 1599.241244] process_one_work+0x223/0x3c0 [ 1599.245371] worker_thread+0x50/0x410 [ 1599.249146] ? process_one_work+0x3c0/0x3c0 [ 1599.253460] kthread+0x124/0x150 [ 1599.256811] ? set_kthread_struct+0x50/0x50 [ 1599.261110] ret_from_fork+0x1f/0x30 [ 1599.264820] </TASK> [ 1599.267171] INFO: task systemd-journal:1098 blocked for more than 123 seconds. [ 1599.274538] Not tainted 5.15.63-flatcar #1 [ 1599.279282] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.287256] task:systemd-journal state:D stack: 0 pid: 1098 ppid: 1 flags:0x00000224 [ 1599.295753] Call Trace: [ 1599.298343] <TASK> [ 1599.300570] __schedule+0x2eb/0x8d0 [ 1599.304178] schedule+0x5b/0xd0 [ 1599.307434] wait_transaction_locked+0x8a/0xd0 [jbd2] [ 1599.312814] ? wait_woken+0x70/0x70 [ 1599.316431] add_transaction_credits+0xd9/0x2b0 [jbd2] [ 1599.321722] start_this_handle+0xfb/0x520 [jbd2] [ 1599.326460] ? __cond_resched+0x16/0x50 [ 1599.330414] jbd2__journal_start+0xfb/0x1e0 [jbd2] [ 1599.335331] __ext4_journal_start_sb+0xf8/0x110 [ext4] [ 1599.340615] ext4_truncate+0x167/0x480 [ext4] [ 1599.345134] ext4_setattr+0x59a/0x9a0 [ext4] [ 1599.349567] ? virtnet_poll+0x31b/0x45b [virtio_net] [ 1599.354663] ? common_interrupt+0xf/0xa0 [ 1599.358705] notify_change+0x3c1/0x540 [ 1599.362591] ? do_truncate+0x7d/0xd0 [ 1599.366292] do_truncate+0x7d/0xd0 [ 1599.369836] do_sys_ftruncate+0xc9/0x150 [ 1599.373882] do_syscall_64+0x38/0x90 [ 1599.377581] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1599.382757] RIP: 0033:0x7fc405986757 [ 1599.386449] RSP: 002b:00007ffdf6776af8 EFLAGS: 00000202 ORIG_RAX: 000000000000004d [ 1599.394126] RAX: ffffffffffffffda RBX: 00007ffdf6776b40 RCX: 00007fc405986757 [ 1599.401371] RDX: 0000557b78aa8f40 RSI: 0000000001000000 RDI: 0000000000000015 [ 1599.408615] RBP: 0000557b78aac520 R08: 0000000000000001 R09: 0000557b78aac5ac [ 1599.415860] R10: 0000000000000000 R11: 0000000000000202 R12: 0000557b78a9c600 [ 1599.423119] R13: 00007ffdf6776b38 R14: 0000000000000003 R15: 0000000000000000 [ 1599.430406] </TASK> [ 1599.432754] INFO: task systemd-timesyn:1277 blocked for more than 123 seconds. [ 1599.440097] Not tainted 5.15.63-flatcar #1 [ 1599.444842] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.452799] task:systemd-timesyn state:D stack: 0 pid: 1277 ppid: 1 flags:0x00000224 [ 1599.461268] Call Trace: [ 1599.463836] <TASK> [ 1599.466046] __schedule+0x2eb/0x8d0 [ 1599.469684] schedule+0x5b/0xd0 [ 1599.472946] wait_transaction_locked+0x8a/0xd0 [jbd2] [ 1599.478133] ? wait_woken+0x70/0x70 [ 1599.481839] add_transaction_credits+0xd9/0x2b0 [jbd2] [ 1599.487387] ? __fget_files+0x79/0xb0 [ 1599.491185] start_this_handle+0xfb/0x520 [jbd2] [ 1599.495963] ? nd_jump_link+0x4d/0xc0 [ 1599.499752] ? __cond_resched+0x16/0x50 [ 1599.503708] jbd2__journal_start+0xfb/0x1e0 [jbd2] [ 1599.508620] __ext4_journal_start_sb+0xf8/0x110 [ext4] [ 1599.513897] ext4_dirty_inode+0x35/0x80 [ext4] [ 1599.518477] __mark_inode_dirty+0x144/0x320 [ 1599.522795] ext4_setattr+0x1fb/0x9a0 [ext4] [ 1599.527200] notify_change+0x3c1/0x540 [ 1599.531071] ? vfs_utimes+0x139/0x220 [ 1599.534845] vfs_utimes+0x139/0x220 [ 1599.538446] do_utimes+0xb4/0x120 [ 1599.541874] __x64_sys_utimensat+0x70/0xb0 [ 1599.546132] ? syscall_trace_enter.constprop.0+0x143/0x1c0 [ 1599.551751] do_syscall_64+0x38/0x90 [ 1599.555443] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1599.560628] RIP: 0033:0x7fce21af901f [ 1599.564858] RSP: 002b:00007ffedd36c8c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000118 [ 1599.572559] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fce21af901f [ 1599.579806] RDX: 0000000000000000 RSI: 00007ffedd36c8d0 RDI: 00000000ffffff9c [ 1599.587062] RBP: 00007ffedd36c8d0 R08: 0000000000000000 R09: 00007ffedd36c760 [ 1599.594313] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 [ 1599.601558] R13: 00000000ffffffff R14: ffffffffffffffff R15: 00000000ffffffff [ 1599.608806] </TASK> [ 1599.611124] INFO: task bash:1925 blocked for more than 123 seconds. [ 1599.617618] Not tainted 5.15.63-flatcar #1 [ 1599.622347] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.630283] task:bash state:D stack: 0 pid: 1925 ppid: 1924 flags:0x00000004 [ 1599.638750] Call Trace: [ 1599.641309] <TASK> [ 1599.643528] __schedule+0x2eb/0x8d0 [ 1599.647140] schedule+0x5b/0xd0 [ 1599.650399] wait_transaction_locked+0x8a/0xd0 [jbd2] [ 1599.655571] ? wait_woken+0x70/0x70 [ 1599.659188] add_transaction_credits+0xd9/0x2b0 [jbd2] [ 1599.664444] ? pagecache_get_page+0x28b/0x470 [ 1599.668914] start_this_handle+0xfb/0x520 [jbd2] [ 1599.673664] ? __cond_resched+0x16/0x50 [ 1599.677615] jbd2__journal_start+0xfb/0x1e0 [jbd2] [ 1599.682525] __ext4_journal_start_sb+0xf8/0x110 [ext4] [ 1599.687801] __ext4_new_inode+0x73f/0x1710 [ext4] [ 1599.692639] ext4_create+0x115/0x1d0 [ext4] [ 1599.696968] path_openat+0xf48/0x1280 [ 1599.700751] ? _raw_spin_unlock_irqrestore+0xa/0x30 [ 1599.705742] ? __wake_up_common_lock+0x8a/0xc0 [ 1599.710299] do_filp_open+0xa9/0x150 [ 1599.713990] ? vfs_statx+0x74/0x130 [ 1599.717615] ? __check_object_size+0x146/0x160 [ 1599.722179] do_sys_openat2+0x9b/0x160 [ 1599.726057] __x64_sys_openat+0x54/0xa0 [ 1599.730003] do_syscall_64+0x38/0x90 [ 1599.733691] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1599.738870] RIP: 0033:0x7f138fdb5337 [ 1599.742558] RSP: 002b:00007ffdc49dcaa0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 [ 1599.750249] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f138fdb5337 [ 1599.757497] RDX: 0000000000000241 RSI: 00005583f2829d70 RDI: 00000000ffffff9c [ 1599.764747] RBP: 00005583f2829d70 R08: 0000000000000000 R09: 0000000000000000 [ 1599.771998] R10: 0000000000000180 R11: 0000000000000246 R12: 0000000000000241 [ 1599.779258] R13: 0000000000000000 R14: 00005583f1f45534 R15: 0000000000000000 [ 1599.786510] </TASK> [ 1599.788906] INFO: task MVStore backgro:8970 blocked for more than 123 seconds. [ 1599.796262] Not tainted 5.15.63-flatcar #1 [ 1599.800992] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.808931] task:MVStore backgro state:D stack: 0 pid: 8970 ppid: 8062 flags:0x00000000 [ 1599.817398] Call Trace: [ 1599.819968] <TASK> [ 1599.822205] __schedule+0x2eb/0x8d0 [ 1599.825816] schedule+0x5b/0xd0 [ 1599.829073] wait_transaction_locked+0x8a/0xd0 [jbd2] [ 1599.834250] ? wait_woken+0x70/0x70 [ 1599.837852] add_transaction_credits+0xd9/0x2b0 [jbd2] [ 1599.843108] start_this_handle+0xfb/0x520 [jbd2] [ 1599.847859] ? __cond_resched+0x16/0x50 [ 1599.851810] jbd2__journal_start+0xfb/0x1e0 [jbd2] [ 1599.856715] __ext4_journal_start_sb+0xf8/0x110 [ext4] [ 1599.861992] ext4_dirty_inode+0x35/0x80 [ext4] [ 1599.866585] __mark_inode_dirty+0x144/0x320 [ 1599.870892] generic_update_time+0x6c/0xd0 [ 1599.875118] file_update_time+0x127/0x140 [ 1599.879242] ? generic_write_checks+0x61/0xc0 [ 1599.883721] ext4_buffered_write_iter+0x5a/0x180 [ext4] [ 1599.889103] do_iter_readv_writev+0x14f/0x1b0 [ 1599.893582] do_iter_write+0x80/0x1c0 [ 1599.897370] ovl_write_iter+0x2d3/0x450 [overlay] [ 1599.902195] new_sync_write+0x119/0x1b0 [ 1599.906151] ? intel_get_event_constraints+0x300/0x390 [ 1599.911403] vfs_write+0x1de/0x270 [ 1599.914917] __x64_sys_pwrite64+0x91/0xc0 [ 1599.919039] do_syscall_64+0x38/0x90 [ 1599.922727] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1599.927968] RIP: 0033:0x7f2f532424a3 [ 1599.931659] RSP: 002b:00007f2f2cc8aa78 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 [ 1599.939352] RAX: ffffffffffffffda RBX: 00007f2f2cc8bb38 RCX: 00007f2f532424a3 [ 1599.946606] RDX: 0000000000001000 RSI: 00007f2f2c769d90 RDI: 0000000000000014 [ 1599.953875] RBP: 00007f2f2cc8aaf0 R08: 0000000000000000 R09: 0000000000000000 [ 1599.961127] R10: 00000000000a3000 R11: 0000000000000246 R12: 0000000000000012 [ 1599.968527] R13: 00007f2f2c769d90 R14: 00000000000a3000 R15: 00007f2f2f94b800 [ 1599.975775] </TASK> [ 1599.978135] INFO: task k3s-server:12051 blocked for more than 123 seconds. [ 1599.985142] Not tainted 5.15.63-flatcar #1 [ 1599.989873] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1599.997816] task:k3s-server state:D stack: 0 pid:12051 ppid: 1 flags:0x00000000 [ 1600.006283] Call Trace: [ 1600.008862] <TASK> [ 1600.011083] __schedule+0x2eb/0x8d0 [ 1600.014779] schedule+0x5b/0xd0 [ 1600.018034] rwsem_down_write_slowpath+0x220/0x4f0 [ 1600.022947] chown_common+0x152/0x250 [ 1600.026740] ? __do_sys_newfstat+0x57/0x60 [ 1600.030950] ? __fget_files+0x79/0xb0 [ 1600.034749] ksys_fchown+0x74/0xb0 [ 1600.038283] __x64_sys_fchown+0x16/0x20 [ 1600.042230] do_syscall_64+0x38/0x90 [ 1600.045922] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1600.051091] RIP: 0033:0x3f8045f [ 1600.054346] RSP: 002b:00007f749fe0a670 EFLAGS: 00000202 ORIG_RAX: 000000000000005d [ 1600.062050] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000003f8045f [ 1600.069297] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000188 [ 1600.076557] RBP: 00007f749dfd2498 R08: 0000000000000188 R09: 000000000572a6fb [ 1600.083808] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000188 [ 1600.091051] R13: 00007f749f5416cd R14: 0000000000080006 R15: 00000000000001a4 [ 1600.098312] </TASK> [ 1600.100611] INFO: task k3s-server:12052 blocked for more than 123 seconds. [ 1600.107601] Not tainted 5.15.63-flatcar #1 [ 1600.112344] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1600.120281] task:k3s-server state:D stack: 0 pid:12052 ppid: 1 flags:0x00000000 [ 1600.128758] Call Trace: [ 1600.131315] <TASK> [ 1600.133536] __schedule+0x2eb/0x8d0 [ 1600.137136] schedule+0x5b/0xd0 [ 1600.140408] wait_transaction_locked+0x8a/0xd0 [jbd2] [ 1600.145574] ? wait_woken+0x70/0x70 [ 1600.149190] add_transaction_credits+0xd9/0x2b0 [jbd2] [ 1600.154442] ? __cond_resched+0x16/0x50 [ 1600.158395] ? dput+0x32/0x310 [ 1600.161559] start_this_handle+0xfb/0x520 [jbd2] [ 1600.166290] ? asm_sysvec_apic_timer_interrupt+0x15/0x20 [ 1600.171713] ? __cond_resched+0x16/0x50 [ 1600.175660] jbd2__journal_start+0xfb/0x1e0 [jbd2] [ 1600.180568] __ext4_journal_start_sb+0xf8/0x110 [ext4] [ 1600.185846] ext4_dirty_inode+0x35/0x80 [ext4] [ 1600.190441] __mark_inode_dirty+0x144/0x320 [ 1600.194737] ext4_setattr+0x1fb/0x9a0 [ext4] [ 1600.199134] notify_change+0x3c1/0x540 [ 1600.203002] ? chown_common+0x168/0x250 [ 1600.206957] chown_common+0x168/0x250 [ 1600.210731] ? __fget_files+0x79/0xb0 [ 1600.214502] ksys_fchown+0x74/0xb0 [ 1600.218017] __x64_sys_fchown+0x16/0x20 [ 1600.221965] do_syscall_64+0x38/0x90 [ 1600.225674] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1600.230851] RIP: 0033:0x3f8045f [ 1600.234114] RSP: 002b:00007f749fde7670 EFLAGS: 00000202 ORIG_RAX: 000000000000005d [ 1600.241794] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000003f8045f [ 1600.249050] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000145 [ 1600.256388] RBP: 00007f749e2213c8 R08: 0000000000000145 R09: 000000000572a6fb [ 1600.263636] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000145 [ 1600.270890] R13: 00007f749dfbef0d R14: 0000000000080006 R15: 00000000000001a4 [ 1600.278138] </TASK> [ 1600.280436] INFO: task k3s-server:12055 blocked for more than 124 seconds. [ 1600.287449] Not tainted 5.15.63-flatcar #1 [ 1600.292184] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1600.300127] task:k3s-server state:D stack: 0 pid:12055 ppid: 1 flags:0x00000000 [ 1600.308590] Call Trace: [ 1600.311151] <TASK> [ 1600.313358] __schedule+0x2eb/0x8d0 [ 1600.316957] schedule+0x5b/0xd0 [ 1600.320208] rwsem_down_write_slowpath+0x220/0x4f0 [ 1600.325113] chown_common+0x152/0x250 [ 1600.328890] ? __do_sys_newfstat+0x57/0x60 [ 1600.333107] ? __fget_files+0x79/0xb0 [ 1600.336885] ksys_fchown+0x74/0xb0 [ 1600.340400] __x64_sys_fchown+0x16/0x20 [ 1600.344346] do_syscall_64+0x38/0x90 [ 1600.348035] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1600.353218] RIP: 0033:0x3f8045f [ 1600.356471] RSP: 002b:00007f749fcae670 EFLAGS: 00000202 ORIG_RAX: 000000000000005d [ 1600.364149] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000003f8045f [ 1600.371397] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000019c [ 1600.378648] RBP: 00007f749f539888 R08: 000000000000019c R09: 000000000572a6fb [ 1600.385895] R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000019c [ 1600.393155] R13: 00007f749e2e5a3d R14: 0000000000080006 R15: 00000000000001a4 [ 1600.400407] </TASK> [ 1600.402761] INFO: task k3s-server:12057 blocked for more than 124 seconds. [ 1600.409779] Not tainted 5.15.63-flatcar #1 [ 1600.414512] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1600.422470] task:k3s-server state:D stack: 0 pid:12057 ppid: 1 flags:0x00000000 [ 1600.430934] Call Trace: [ 1600.433510] <TASK> [ 1600.435722] __schedule+0x2eb/0x8d0 [ 1600.439328] schedule+0x5b/0xd0 [ 1600.442583] rwsem_down_write_slowpath+0x220/0x4f0 [ 1600.447495] chown_common+0x152/0x250 [ 1600.451274] ? __do_sys_newfstat+0x57/0x60 [ 1600.455483] ? __fget_files+0x79/0xb0 [ 1600.459258] ksys_fchown+0x74/0xb0 [ 1600.462773] __x64_sys_fchown+0x16/0x20 [ 1600.466724] do_syscall_64+0x38/0x90 [ 1600.470416] entry_SYSCALL_64_after_hwframe+0x61/0xcb [ 1600.475604] RIP: 0033:0x3f8045f [ 1600.478857] RSP: 002b:00007f749fc28670 EFLAGS: 00000202 ORIG_RAX: 000000000000005d [ 1600.486539] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000003f8045f [ 1600.493788] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000196 [ 1600.501050] RBP: 00007f749f64dac8 R08: 0000000000000196 R09: 000000000572a6fb [ 1600.508318] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000196 [ 1600.515569] R13: 00007f749eadef0d R14: 0000000000080006 R15: 00000000000001a4 [ 1600.522817] </TASK>
