======================================================
WARNING: possible circular locking dependency detected
5.0.0-next-20190306 #4 Not tainted
------------------------------------------------------
syz-executor.3/3169 is trying to acquire lock:
0000000001b04cb4 (&p->lock){+.+.}, at: seq_read+0x71/0x1130 fs/seq_file.c:161
but task is already holding lock:
000000005c2e9aae (sb_writers#5){.+.+}, at: file_start_write include/linux/fs.h:2822 [inline]
000000005c2e9aae (sb_writers#5){.+.+}, at: do_sendfile+0x9b9/0xd00 fs/read_write.c:1441
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (sb_writers#5){.+.+}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202
percpu_down_read include/linux/percpu-rwsem.h:36 [inline]
__sb_start_write+0x20b/0x360 fs/super.c:1613
sb_start_write include/linux/fs.h:1618 [inline]
mnt_want_write+0x3f/0xc0 fs/namespace.c:358
ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:24
ovl_do_remove+0xe9/0xd70 fs/overlayfs/dir.c:840
ovl_rmdir+0x1b/0x20 fs/overlayfs/dir.c:890
vfs_rmdir fs/namei.c:3878 [inline]
vfs_rmdir+0x19c/0x470 fs/namei.c:3857
do_rmdir+0x39e/0x420 fs/namei.c:3939
__do_sys_rmdir fs/namei.c:3957 [inline]
__se_sys_rmdir fs/namei.c:3955 [inline]
__x64_sys_rmdir+0x36/0x40 fs/namei.c:3955
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #2 (&ovl_i_mutex_dir_key[depth]#2){++++}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202
down_read+0x3b/0x90 kernel/locking/rwsem.c:24
inode_lock_shared include/linux/fs.h:779 [inline]
lookup_slow+0x4a/0x80 fs/namei.c:1685
walk_component+0x74b/0x2000 fs/namei.c:1808
link_path_walk.part.0+0x980/0x1340 fs/namei.c:2139
link_path_walk fs/namei.c:2070 [inline]
path_openat+0x202/0x46e0 fs/namei.c:3532
do_filp_open+0x1a1/0x280 fs/namei.c:3563
do_open_execat+0x137/0x690 fs/exec.c:856
__do_execve_file.isra.0+0x178d/0x23f0 fs/exec.c:1758
do_execveat_common fs/exec.c:1865 [inline]
do_execve fs/exec.c:1882 [inline]
__do_sys_execve fs/exec.c:1958 [inline]
__se_sys_execve fs/exec.c:1953 [inline]
__x64_sys_execve+0x8f/0xc0 fs/exec.c:1953
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (&sig->cred_guard_mutex){+.+.}:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_killable_nested+0x16/0x20 kernel/locking/mutex.c:1102
lock_trace+0x4a/0xe0 fs/proc/base.c:388
proc_pid_stack+0x13e/0x2c0 fs/proc/base.c:438
proc_single_show+0xf6/0x170 fs/proc/base.c:743
seq_read+0x4db/0x1130 fs/seq_file.c:229
do_loop_readv_writev fs/read_write.c:700 [inline]
do_loop_readv_writev fs/read_write.c:687 [inline]
do_iter_read+0x4a9/0x660 fs/read_write.c:921
vfs_readv+0xf0/0x160 fs/read_write.c:983
do_preadv+0x1c4/0x280 fs/read_write.c:1067
__do_sys_preadv fs/read_write.c:1117 [inline]
__se_sys_preadv fs/read_write.c:1112 [inline]
__x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1112
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&p->lock){+.+.}:
check_prevs_add kernel/locking/lockdep.c:2324 [inline]
validate_chain kernel/locking/lockdep.c:2705 [inline]
__lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3692
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202
__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
seq_read+0x71/0x1130 fs/seq_file.c:161
do_loop_readv_writev fs/read_write.c:700 [inline]
do_loop_readv_writev fs/read_write.c:687 [inline]
do_iter_read+0x4a9/0x660 fs/read_write.c:921
vfs_readv+0xf0/0x160 fs/read_write.c:983
kernel_readv fs/splice.c:358 [inline]
default_file_splice_read+0x475/0x890 fs/splice.c:413
do_splice_to+0x12a/0x190 fs/splice.c:876
splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953
do_splice_direct+0x1da/0x2a0 fs/splice.c:1062
do_sendfile+0x597/0xd00 fs/read_write.c:1442
__do_sys_sendfile64 fs/read_write.c:1503 [inline]
__se_sys_sendfile64 fs/read_write.c:1489 [inline]
__x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1489
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:
&p->lock --> &ovl_i_mutex_dir_key[depth]#2 --> sb_writers#5
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sb_writers#5);
lock(&ovl_i_mutex_dir_key[depth]#2);
lock(sb_writers#5);
lock(&p->lock);
*** DEADLOCK ***
1 lock held by syz-executor.3/3169:
#0: 000000005c2e9aae (sb_writers#5){.+.+}, at: file_start_write include/linux/fs.h:2822 [inline]
#0: 000000005c2e9aae (sb_writers#5){.+.+}, at: do_sendfile+0x9b9/0xd00 fs/read_write.c:1441
stack backtrace:
CPU: 0 PID: 3169 Comm: syz-executor.3 Not tainted 5.0.0-next-20190306 #4
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:1562
check_prev_add.constprop.0+0xf11/0x23c0 kernel/locking/lockdep.c:2211
check_prevs_add kernel/locking/lockdep.c:2324 [inline]
validate_chain kernel/locking/lockdep.c:2705 [inline]
__lock_acquire+0x239c/0x3fb0 kernel/locking/lockdep.c:3692
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4202
__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
seq_read+0x71/0x1130 fs/seq_file.c:161
do_loop_readv_writev fs/read_write.c:700 [inline]
do_loop_readv_writev fs/read_write.c:687 [inline]
do_iter_read+0x4a9/0x660 fs/read_write.c:921
vfs_readv+0xf0/0x160 fs/read_write.c:983
kernel_readv fs/splice.c:358 [inline]
default_file_splice_read+0x475/0x890 fs/splice.c:413
do_splice_to+0x12a/0x190 fs/splice.c:876
splice_direct_to_actor+0x2d2/0x970 fs/splice.c:953
do_splice_direct+0x1da/0x2a0 fs/splice.c:1062
do_sendfile+0x597/0xd00 fs/read_write.c:1442
__do_sys_sendfile64 fs/read_write.c:1503 [inline]
__se_sys_sendfile64 fs/read_write.c:1489 [inline]
__x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1489
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457f29
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fbe94638c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457f29
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000040000000009 R11: 0000000000000246 R12: 00007fbe946396d4
R13: 00000000004c4ece R14: 00000000004d8bf8 R15: 00000000ffffffff