RBP: 0000000000000001 R08: ffffffffffffffc0 R09: 00007f2511667e40 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f251166d410 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 ====================================================== WARNING: possible circular locking dependency detected 5.17.0-next-20220401-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor358/3566 is trying to acquire lock: ffff888010c64d38 ((wq_completion)events){+.+.}-{0:0}, at: flush_workqueue+0x135/0x1440 kernel/workqueue.c:2828 but task is already holding lock: ffff88801d9640e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa5/0xd0 fs/super.c:362 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&type->s_umount_key#32){++++}-{3:3}: down_read+0x98/0x440 kernel/locking/rwsem.c:1461 iterate_supers+0xdb/0x290 fs/super.c:692 drop_caches_sysctl_handler+0xdb/0x110 fs/drop_caches.c:62 proc_sys_call_handler+0x4a1/0x6e0 fs/proc/proc_sysctl.c:604 call_write_iter include/linux/fs.h:2051 [inline] do_iter_readv_writev+0x3d1/0x640 fs/read_write.c:726 do_iter_write+0x182/0x700 fs/read_write.c:852 vfs_iter_write+0x70/0xa0 fs/read_write.c:893 iter_file_splice_write+0x723/0xc70 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] direct_splice_actor+0x110/0x180 fs/splice.c:936 splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891 do_splice_direct+0x1a7/0x270 fs/splice.c:979 do_sendfile+0xae0/0x1240 fs/read_write.c:1246 __do_sys_sendfile64 fs/read_write.c:1305 [inline] __se_sys_sendfile64 fs/read_write.c:1297 [inline] __x64_sys_sendfile64+0x149/0x210 fs/read_write.c:1297 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #2 (sb_writers#3){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1699 [inline] sb_start_write include/linux/fs.h:1769 [inline] file_start_write include/linux/fs.h:2786 [inline] kernel_write fs/read_write.c:564 [inline] kernel_write+0x2ac/0x540 fs/read_write.c:555 p9_fd_write net/9p/trans_fd.c:428 [inline] p9_write_work+0x25e/0xca0 net/9p/trans_fd.c:479 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 -> #1 ((work_completion)(&m->wq)){+.+.}-{0:0}: process_one_work+0x905/0x1610 kernel/workqueue.c:2265 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 -> #0 ((wq_completion)events){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3096 [inline] check_prevs_add kernel/locking/lockdep.c:3219 [inline] validate_chain kernel/locking/lockdep.c:3834 [inline] __lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5060 lock_acquire kernel/locking/lockdep.c:5672 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637 flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831 flush_scheduled_work include/linux/workqueue.h:583 [inline] ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202 generic_shutdown_super+0x14c/0x400 fs/super.c:462 kill_block_super+0x97/0xf0 fs/super.c:1394 deactivate_locked_super+0x94/0x160 fs/super.c:332 deactivate_super+0xad/0xd0 fs/super.c:363 cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:37 [inline] do_exit+0xaff/0x2a00 kernel/exit.c:795 do_group_exit+0xd2/0x2f0 kernel/exit.c:925 __do_sys_exit_group kernel/exit.c:936 [inline] __se_sys_exit_group kernel/exit.c:934 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae other info that might help us debug this: Chain exists of: (wq_completion)events --> sb_writers#3 --> &type->s_umount_key#32 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&type->s_umount_key#32); lock(sb_writers#3); lock(&type->s_umount_key#32); lock((wq_completion)events); *** DEADLOCK *** 1 lock held by syz-executor358/3566: #0: ffff88801d9640e0 (&type->s_umount_key#32){++++}-{3:3}, at: deactivate_super+0xa5/0xd0 fs/super.c:362 stack backtrace: CPU: 1 PID: 3566 Comm: syz-executor358 Not tainted 5.17.0-next-20220401-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2176 check_prev_add kernel/locking/lockdep.c:3096 [inline] check_prevs_add kernel/locking/lockdep.c:3219 [inline] validate_chain kernel/locking/lockdep.c:3834 [inline] __lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5060 lock_acquire kernel/locking/lockdep.c:5672 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5637 flush_workqueue+0x164/0x1440 kernel/workqueue.c:2831 flush_scheduled_work include/linux/workqueue.h:583 [inline] ext4_put_super+0x99/0x1150 fs/ext4/super.c:1202 generic_shutdown_super+0x14c/0x400 fs/super.c:462 kill_block_super+0x97/0xf0 fs/super.c:1394 deactivate_locked_super+0x94/0x160 fs/super.c:332 deactivate_super+0xad/0xd0 fs/super.c:363 cleanup_mnt+0x3a2/0x540 fs/namespace.c:1186 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:37 [inline] do_exit+0xaff/0x2a00 kernel/exit.c:795 do_group_exit+0xd2/0x2f0 kernel/exit.c:925 __do_sys_exit_group kernel/exit.c:936 [inline] __se_sys_exit_group kernel/exit.c:934 [inline] __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f25115f8819 Code: Unable to access opcode bytes at RIP 0x7f25115f87ef. RSP: 002b:00007ffcaf8cf478 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f251166d410 RCX: 00007f25115f8819 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001 RBP: 0000000000000001 R08: ffffffffffffffc0 R09: 00007f2511667e40 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f251166d410 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001