Hi, I encountered below crash during the sync system call possibly coming from the stress threads spawned because of the --io options which does sync system calls. I believe the crash is because of this upstream patch https://patchwork.kernel.org/project/linux-fsdevel/patch/20171212163830.GC3919388@xxxxxxxxxxxxxxxxxxxxxxxxxxx/ which introduces read write semaphore. I am not sure how to mitigate this issue, any advice will be appreciated. How to reproduce: 1. apt-get install stress 2. stress -c 8 --io 8 --vm 8 --hdd 4 Platform: Nvidia Jetson AGX XAVIER, with 32GB eMMC 5.1 and 256 bit 32GB LPDDR4 RAM. Kernel: 4.9.201-rt134 CPU: 8-Core ARM v8.2 64-Bit CPU, 8 MB L2 + 4 MB L3 Call stack: [ 1813.814464] INFO: task stress blocked for more than 120 seconds. [ 1813.814610] Not tainted 4.9.201-rt134 #2 [ 1813.814613] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1813.814615] stress D 0 11510 11504 0x00000008 [ 1813.814616] Call trace: [ 1813.814617] [<ffffff8008085eac>] __switch_to+0x98/0xb8 [ 1813.814618] [<ffffff8008f23b2c>] __schedule+0x270/0x570 [ 1813.814619] [<ffffff8008f23e74>] schedule+0x48/0xe0 [ 1813.814620] [<ffffff8008f25384>] __rt_mutex_slowlock+0xc4/0x144 [ 1813.814622] [<ffffff8008f2578c>] rt_mutex_slowlock_locked+0xcc/0x1e4 [ 1813.814624] [<ffffff8008f25910>] rt_mutex_slowlock.constprop.22+0x6c/0xb0 [ 1813.814625] [<ffffff8008f25c70>] rt_mutex_lock_state+0x94/0xc0 [ 1813.814626] [<ffffff8008f25f48>] __down_write_common+0x38/0x140 [ 1813.814627] [<ffffff8008f26148>] __down_write+0x24/0x30 [ 1813.814628] [<ffffff8008f25198>] down_write+0x20/0x2c [ 1813.814629] [<ffffff8008279a08>] sync_inodes_sb+0x98/0x220 [ 1813.814630] [<ffffff8008280350>] sync_inodes_one_sb+0x28/0x34 [ 1813.814631] [<ffffff80082497d4>] iterate_supers+0x114/0x118 [ 1813.814632] [<ffffff8008280738>] sys_sync+0x44/0xac [ 1813.814633] [<ffffff8008083100>] el0_svc_naked+0x34/0x38 [ 363.940264] Showing all locks held in the system: [ 363.946481] 6 locks held by kworker/u16:0/7: [ 363.950503] #0: ("writeback"){......}, at: [<ffffff80080d3ed0>] process_one_work+0x1c0/0x670 [ 363.959692] #1: ((&(&wb->dwork)->work)){......}, at: [<ffffff80080d3ed0>] process_one_work+0x1c0/0x670 [ 363.969137] #2: (&type->s_umount_key#31){......}, at: [<ffffff800826b124>] trylock_super+0x24/0x70 [ 363.978848] #3: (&sbi->s_journal_flag_rwsem){......}, at: [<ffffff80081e7688>] do_writepages+0x48/0xa0 [ 363.988651] #4: (jbd2_handle){......}, at: [<ffffff8008369a80>] start_this_handle+0xf0/0x3b8 [ 363.997576] #5: (&ei->i_data_sem){......}, at: [<ffffff8008315228>] ext4_map_blocks+0xd8/0x5a8 [ 364.006530] 2 locks held by khungtaskd/740: [ 364.010699] #0: (rcu_read_lock){......}, at: [<ffffff800818f8e0>] watchdog+0xf0/0x510 [ 364.018749] #1: (tasklist_lock){......}, at: [<ffffff8008117f64>] debug_show_all_locks+0x3c/0x1b8 [ 364.027960] 1 lock held by in:imklog/5258: [ 364.032051] #0: (&f->f_pos_lock){......}, at: [<ffffff800828c120>] __fdget_pos+0x50/0x60 [ 364.040366] 4 locks held by rs:main Q:Reg/5259: [ 364.044912] #0: (&f->f_pos_lock){......}, at: [<ffffff800828c120>] __fdget_pos+0x50/0x60 [ 364.053311] #1: (rcu_read_lock){......}, at: [<ffffff800811578c>] cpuacct_charge+0x44/0xe8 [ 364.061547] #2: (rcu_read_lock){......}, at: [<ffffff8008283b78>] dput.part.5+0x50/0x328 [ 364.070289] #3: (&(&(&dentry->d_lockref.lock)->lock)->wait_lock){......}, at: [<ffffff8008fef254>] __schedule+0x84/0x6f0 [ 364.081077] 2 locks held by agetty/6375: [ 364.085384] #0: (&tty->ldisc_sem){......}, at: [<ffffff8008ff2b94>] ldsem_down_read+0x2c/0x38 [ 364.093567] #1: (&tty->atomic_write_lock){......}, at: [<ffffff80087399b8>] tty_write_lock+0x28/0x60 [ 364.103206] 2 locks held by stress/12304: [ 364.107298] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.116317] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.125589] 2 locks held by stress/12308: [ 364.129266] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.138627] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.147821] 2 locks held by stress/12312: [ 364.152098] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.161392] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.170913] 2 locks held by stress/12314: [ 364.174761] #0: (sb_writers#5){......}, at: [<ffffff800826631c>] vfs_write+0x19c/0x1b0 [ 364.183180] #1: (&sb->s_type->i_mutex_key#13){......}, at: [<ffffff800830e564>] ext4_file_write_iter+0x44/0x388 [ 364.193580] 2 locks held by stress/12316: [ 364.197423] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.206786] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.215981] 2 locks held by stress/12320: [ 364.219829] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.229448] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.238717] 2 locks held by stress/12323: [ 364.242495] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.251680] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.261129] 2 locks held by stress/12326: [ 364.265237] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.274688] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.283796] 2 locks held by stress/12330: [ 364.287641] #0: (&type->s_umount_key#31){......}, at: [<ffffff800826b368>] iterate_supers+0x78/0x140 [ 364.297261] #1: (&bdi->wb_switch_rwsem){......}, at: [<ffffff800829e630>] sync_inodes_sb+0x98/0x2a0 [ 364.306720] 2 locks held by Xorg/14558: [ 364.310301] #0: (&tty->legacy_mutex){......}, at: [<ffffff8008747d84>] tty_lock_interruptible+0x4c/0xb0 [ 364.319683] #1: (tasklist_lock){......}, at: [<ffffff800873f088>] tty_open+0x438/0x5b0 Best Regards, Dipen Patel
