block2mtd: error: cannot open device /tmp/ovl_bug_7ivaQs/merged/nonexistent ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor469/6041 is trying to acquire lock: ffff888024d8c460 (sb_writers#6){.+.+}-{0:0}, at: ovl_create_object+0x130/0x3b0 fs/overlayfs/dir.c:705 but task is already holding lock: ffff88805802a7a8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] ffff88805802a7a8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: lookup_open+0xb13/0x1990 fs/namei.c:4458 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 down_read+0x99/0x4c0 kernel/locking/rwsem.c:1574 inode_lock_shared include/linux/fs.h:1039 [inline] lookup_slow+0x42/0x70 fs/namei.c:1935 walk_component fs/namei.c:2282 [inline] lookup_last fs/namei.c:2789 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2813 filename_lookup+0x202/0x590 fs/namei.c:2842 kern_path+0x37/0x50 fs/namei.c:3036 lookup_bdev+0xd8/0x2a0 block/bdev.c:1268 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1123 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2.isra.0+0x2ee/0xbd0 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0xbd/0xd0 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x199/0x300 kernel/params.c:591 module_attr_store+0x58/0x80 kernel/params.c:906 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 iter_file_splice_write+0x830/0x10b0 fs/splice.c:736 do_splice_from fs/splice.c:936 [inline] do_splice+0x109c/0x1fa0 fs/splice.c:1349 __do_splice+0x33b/0x370 fs/splice.c:1431 __do_sys_splice fs/splice.c:1634 [inline] __se_sys_splice fs/splice.c:1616 [inline] __x64_sys_splice+0x187/0x250 fs/splice.c:1616 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (param_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 kernel_param_lock kernel/params.c:604 [inline] param_attr_store+0xec/0x300 kernel/params.c:589 module_attr_store+0x58/0x80 kernel/params.c:906 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&of->mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:336 iter_file_splice_write+0x830/0x10b0 fs/splice.c:736 do_splice_from fs/splice.c:936 [inline] do_splice+0x109c/0x1fa0 fs/splice.c:1349 __do_splice+0x33b/0x370 fs/splice.c:1431 __do_sys_splice fs/splice.c:1634 [inline] __se_sys_splice fs/splice.c:1616 [inline] __x64_sys_splice+0x187/0x250 fs/splice.c:1616 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&pipe->mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 pipe_lock fs/pipe.c:91 [inline] pipe_lock+0x69/0x80 fs/pipe.c:88 iter_file_splice_write+0x1fd/0x10b0 fs/splice.c:682 do_splice_from fs/splice.c:936 [inline] do_splice+0x109c/0x1fa0 fs/splice.c:1349 __do_splice+0x33b/0x370 fs/splice.c:1431 __do_sys_splice fs/splice.c:1634 [inline] __se_sys_splice fs/splice.c:1616 [inline] __x64_sys_splice+0x187/0x250 fs/splice.c:1616 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_writers#6){.+.+}-{0:0}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write include/linux/fs/super.h:125 [inline] mnt_want_write+0x6f/0x420 fs/namespace.c:494 ovl_create_object+0x130/0x3b0 fs/overlayfs/dir.c:705 lookup_open+0x1255/0x1990 fs/namei.c:4567 open_last_lookups fs/namei.c:4767 [inline] path_openat+0xa2c/0x2440 fs/namei.c:4997 do_file_open+0x20e/0x430 fs/namei.c:5029 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: sb_writers#6 --> param_lock --> &ovl_i_mutex_dir_key[depth] Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ovl_i_mutex_dir_key[depth]); lock(param_lock); lock(&ovl_i_mutex_dir_key[depth]); rlock(sb_writers#6); *** DEADLOCK *** locks held by syz-executor469/6041: 2, last CPU#2: #0: ffff88802a68c460 (sb_writers#13){.+.+}-{0:0}, at: lookup_open+0x150/0x1990 fs/namei.c:4451 #1: ffff88805802a7a8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #1: ffff88805802a7a8 (&ovl_i_mutex_dir_key[depth]){++++}-{4:4}, at: lookup_open+0xb13/0x1990 fs/namei.c:4458 stack backtrace: CPU: 2 UID: 0 PID: 6041 Comm: syz-executor469 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_write include/linux/fs/super.h:125 [inline] mnt_want_write+0x6f/0x420 fs/namespace.c:494 ovl_create_object+0x130/0x3b0 fs/overlayfs/dir.c:705 lookup_open+0x1255/0x1990 fs/namei.c:4567 open_last_lookups fs/namei.c:4767 [inline] path_openat+0xa2c/0x2440 fs/namei.c:4997 do_file_open+0x20e/0x430 fs/namei.c:5029 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fadca23e437 Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007fff380044d0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 000055555dddf400 RCX: 00007fadca23e437 RDX: 0000000000000042 RSI: 00007fadca277192 RDI: ffffffffffffff9c RBP: 00007fadca2770fe R08: 0000000000000000 R09: 0000000000000000 R10: 00000000000001a4 R11: 0000000000000202 R12: 000055555dde1770 R13: 0000000000000026 R14: 00007fff380045a0 R15: 0000000000000002