====================================================== WARNING: possible circular locking dependency detected 5.0.0-rc5-next-20190208 #31 Not tainted ------------------------------------------------------ syz-executor998/7524 is trying to acquire lock: 00000000d0ad08d3 (&ovl_i_mutex_key[depth]){+.+.}, at: inode_lock include/linux/fs.h:760 [inline] 00000000d0ad08d3 (&ovl_i_mutex_key[depth]){+.+.}, at: ovl_write_iter+0x148/0xc20 fs/overlayfs/file.c:231 but task is already holding lock: 00000000816ad2e9 (&pipe->mutex/1){+.+.}, at: pipe_lock_nested fs/pipe.c:62 [inline] 00000000816ad2e9 (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 fs/pipe.c:70 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&pipe->mutex/1){+.+.}: __mutex_lock_common kernel/locking/mutex.c:925 [inline] __mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 pipe_lock_nested fs/pipe.c:62 [inline] pipe_lock+0x6e/0x80 fs/pipe.c:70 iter_file_splice_write+0x18b/0xbe0 fs/splice.c:696 do_splice_from fs/splice.c:847 [inline] do_splice+0x644/0x1260 fs/splice.c:1148 __do_sys_splice fs/splice.c:1415 [inline] __se_sys_splice fs/splice.c:1395 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1395 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #1 (sb_writers#3){.+.+}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x20b/0x360 fs/super.c:1613 sb_start_write include/linux/fs.h:1607 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:358 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24 ovl_setattr+0xdd/0x8b0 fs/overlayfs/inode.c:30 notify_change+0xad9/0xfb0 fs/attr.c:334 do_truncate+0x158/0x220 fs/open.c:63 handle_truncate fs/namei.c:3008 [inline] do_last fs/namei.c:3424 [inline] path_openat+0x2d6a/0x46e0 fs/namei.c:3535 do_filp_open+0x1a1/0x280 fs/namei.c:3565 do_sys_open+0x3fe/0x5d0 fs/open.c:1063 __do_sys_openat fs/open.c:1090 [inline] __se_sys_openat fs/open.c:1084 [inline] __x64_sys_openat+0x9d/0x100 fs/open.c:1084 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&ovl_i_mutex_key[depth]){+.+.}: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 down_write+0x38/0x90 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:760 [inline] ovl_write_iter+0x148/0xc20 fs/overlayfs/file.c:231 call_write_iter include/linux/fs.h:1851 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x613/0x8e0 fs/read_write.c:487 __kernel_write+0x110/0x3b0 fs/read_write.c:506 write_pipe_buf+0x15d/0x1f0 fs/splice.c:793 splice_from_pipe_feed fs/splice.c:499 [inline] __splice_from_pipe+0x395/0x7d0 fs/splice.c:623 splice_from_pipe+0x108/0x170 fs/splice.c:658 default_file_splice_write+0x3c/0x90 fs/splice.c:805 do_splice_from fs/splice.c:847 [inline] do_splice+0x644/0x1260 fs/splice.c:1148 __do_sys_splice fs/splice.c:1415 [inline] __se_sys_splice fs/splice.c:1395 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1395 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: &ovl_i_mutex_key[depth] --> sb_writers#3 --> &pipe->mutex/1 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&pipe->mutex/1); lock(sb_writers#3); lock(&pipe->mutex/1); lock(&ovl_i_mutex_key[depth]); *** DEADLOCK *** 2 locks held by syz-executor998/7524: #0: 00000000089b53ba (sb_writers#8){.+.+}, at: file_start_write include/linux/fs.h:2809 [inline] #0: 00000000089b53ba (sb_writers#8){.+.+}, at: do_splice+0xcf4/0x1260 fs/splice.c:1147 #1: 00000000816ad2e9 (&pipe->mutex/1){+.+.}, at: pipe_lock_nested fs/pipe.c:62 [inline] #1: 00000000816ad2e9 (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 fs/pipe.c:70 stack backtrace: CPU: 0 PID: 7524 Comm: syz-executor998 Not tainted 5.0.0-rc5-next-20190208 #31 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+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1224 check_prev_add kernel/locking/lockdep.c:1855 [inline] check_prevs_add kernel/locking/lockdep.c:1968 [inline] validate_chain kernel/locking/lockdep.c:2339 [inline] __lock_acquire+0x2e7a/0x4790 kernel/locking/lockdep.c:3320 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 down_write+0x38/0x90 kernel/locking/rwsem.c:70 inode_lock include/linux/fs.h:760 [inline] ovl_write_iter+0x148/0xc20 fs/overlayfs/file.c:231 call_write_iter include/linux/fs.h:1851 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x613/0x8e0 fs/read_write.c:487 __kernel_write+0x110/0x3b0 fs/read_write.c:506 write_pipe_buf+0x15d/0x1f0 fs/splice.c:793 splice_from_pipe_feed fs/splice.c:499 [inline] __splice_from_pipe+0x395/0x7d0 fs/splice.c:623 splice_from_pipe+0x108/0x170 fs/splice.c:658 default_file_splice_write+0x3c/0x90 fs/splice.c:805 do_splice_from fs/splice.c:847 [inline] do_splice+0x644/0x1260 fs/splice.c:1148 __do_sys_splice fs/splice.c:1415 [inline] __se_sys_splice fs/splice.c:1395 [inline] __x64_sys_splice+0x2c6/0x330 fs/splice.c:1395 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445919 Code: e8 6c b6 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f24c8f3cda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00000000006dac88 RCX: 0000000000445919 RDX: 000000000000000b RSI: 0000000000000000 RDI: 0000000000000009 RBP: 00000000006dac80 R08: 000100000000ffe0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac8c R13: 00007fff0fc85b0f R14: 00007f24c8f3d9c0 R15: 20c49ba5e353f7cf