Hello, syzbot found the following issue on: HEAD commit: dcf2427b Add linux-next specific files for 20200923 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=111346c5900000 kernel config: https://syzkaller.appspot.com/x/.config?x=254e028a642027c dashboard link: https://syzkaller.appspot.com/bug?extid=ea48ca29949b1820e745 compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ea48ca29949b1820e745@xxxxxxxxxxxxxxxxxxxxxxxxx INFO: task syz-executor.3:19649 can't die for more than 143 seconds. task:syz-executor.3 state:D stack:27488 pid:19649 ppid: 6909 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3777 [inline] __schedule+0xec5/0x2200 kernel/sched/core.c:4526 schedule+0xcf/0x270 kernel/sched/core.c:4604 request_wait_answer+0x505/0x7f0 fs/fuse/dev.c:402 __fuse_request_send fs/fuse/dev.c:421 [inline] fuse_simple_request+0x526/0xc10 fs/fuse/dev.c:503 fuse_lookup_name+0x258/0x5c0 fs/fuse/dir.c:352 fuse_lookup+0xdf/0x390 fs/fuse/dir.c:390 fuse_atomic_open+0x210/0x340 fs/fuse/dir.c:533 atomic_open fs/namei.c:2970 [inline] lookup_open.isra.0+0xc09/0x1350 fs/namei.c:3076 open_last_lookups fs/namei.c:3178 [inline] path_openat+0x96d/0x2730 fs/namei.c:3366 do_filp_open+0x17e/0x3c0 fs/namei.c:3396 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1195 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e179 Code: Bad RIP value. RSP: 002b:00007fe86377ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000021e00 RCX: 000000000045e179 RDX: 0000000000000000 RSI: 0000000020002040 RDI: ffffffffffffff9c RBP: 000000000118cf88 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe2255861f R14: 00007fe86377b9c0 R15: 000000000118cf4c INFO: task syz-executor.3:19649 blocked for more than 143 seconds. Not tainted 5.9.0-rc6-next-20200923-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.3 state:D stack:27488 pid:19649 ppid: 6909 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3777 [inline] __schedule+0xec5/0x2200 kernel/sched/core.c:4526 schedule+0xcf/0x270 kernel/sched/core.c:4604 request_wait_answer+0x505/0x7f0 fs/fuse/dev.c:402 __fuse_request_send fs/fuse/dev.c:421 [inline] fuse_simple_request+0x526/0xc10 fs/fuse/dev.c:503 fuse_lookup_name+0x258/0x5c0 fs/fuse/dir.c:352 fuse_lookup+0xdf/0x390 fs/fuse/dir.c:390 fuse_atomic_open+0x210/0x340 fs/fuse/dir.c:533 atomic_open fs/namei.c:2970 [inline] lookup_open.isra.0+0xc09/0x1350 fs/namei.c:3076 open_last_lookups fs/namei.c:3178 [inline] path_openat+0x96d/0x2730 fs/namei.c:3366 do_filp_open+0x17e/0x3c0 fs/namei.c:3396 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1195 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e179 Code: Bad RIP value. RSP: 002b:00007fe86377ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000021e00 RCX: 000000000045e179 RDX: 0000000000000000 RSI: 0000000020002040 RDI: ffffffffffffff9c RBP: 000000000118cf88 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe2255861f R14: 00007fe86377b9c0 R15: 000000000118cf4c Showing all locks held in the system: 4 locks held by kworker/u4:6/255: #0: ffff8880ae536098 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1292 [inline] #0: ffff8880ae536098 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x284/0x2200 kernel/sched/core.c:4444 #1: ffff8880ae520ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x305/0x440 kernel/sched/psi.c:833 #2: ffff8880ae525698 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5a/0x1f0 kernel/time/timer.c:947 #3: ffffffff8dd778e0 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x12e/0x3e0 lib/debugobjects.c:636 1 lock held by khungtaskd/1176: #0: ffffffff8a553d40 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6221 2 locks held by syz-executor.3/19649: #0: ffff8880552bc850 (&type->i_mutex_dir_key#8){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:792 [inline] #0: ffff8880552bc850 (&type->i_mutex_dir_key#8){++++}-{3:3}, at: open_last_lookups fs/namei.c:3177 [inline] #0: ffff8880552bc850 (&type->i_mutex_dir_key#8){++++}-{3:3}, at: path_openat+0x14a3/0x2730 fs/namei.c:3366 #1: ffff8880552bcc28 (&fi->mutex){+.+.}-{3:3}, at: fuse_lock_inode+0xaf/0xe0 fs/fuse/inode.c:375 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1176 Comm: khungtaskd Not tainted 5.9.0-rc6-next-20200923-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x198/0x1fb lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline] watchdog+0xd89/0xf30 kernel/hung_task.c:339 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 6674 Comm: rs:main Q:Reg Not tainted 5.9.0-rc6-next-20200923-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:find_held_lock+0xec/0x110 kernel/locking/lockdep.c:4922 Code: 00 fc ff df 4c 89 f2 48 c1 ea 03 0f b6 14 02 4c 89 f0 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 11 5b 45 89 3e 4c 89 e0 5d 41 5c <41> 5d 41 5e 41 5f c3 4c 89 f7 e8 75 95 5c 00 eb e5 e8 de 94 5c 00 RSP: 0018:ffffc9000a517d60 EFLAGS: 00000097 RAX: ffff888093356af8 RBX: 1ffff920014a2fb2 RCX: ffffc9000a517dd0 RDX: 0000000000000004 RSI: ffff888214090460 RDI: ffff888093356af8 RBP: ffff888214090460 R08: 0000000000000001 R09: ffff888093356ac8 R10: fffffbfff1769349 R11: 0000000000000000 R12: ffffffff81c19c45 R13: ffff888214090460 R14: ffffc9000a517dd0 R15: 0000000000000001 FS: 00007ff45700c700(0000) GS:ffff8880ae500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0f4c7c4018 CR3: 00000000a44c7000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __lock_release kernel/locking/lockdep.c:5083 [inline] lock_release+0x247/0x890 kernel/locking/lockdep.c:5418 percpu_up_read include/linux/percpu-rwsem.h:99 [inline] __sb_end_write+0x2d/0x1b0 fs/super.c:1638 file_end_write include/linux/fs.h:2782 [inline] vfs_write+0x375/0x700 fs/read_write.c:603 ksys_write+0x12d/0x250 fs/read_write.c:648 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7ff459a501cd Code: c2 20 00 00 75 10 b8 01 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ae fc ff ff 48 89 04 24 b8 01 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 f7 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007ff45700b590 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007ff44c023900 RCX: 00007ff459a501cd RDX: 0000000000000525 RSI: 00007ff44c023900 RDI: 0000000000000006 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00007ff44c023680 R13: 00007ff45700b5b0 R14: 0000556d485ab360 R15: 0000000000000525 --- This report is generated by a bot. 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