======================================================
WARNING: possible circular locking dependency detected
4.14.221-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/20011 is trying to acquire lock:
(&p->lock){+.+.}, at: [<ffffffff818e5eaa>] seq_read+0xba/0x1120 fs/seq_file.c:165
but task is already holding lock:
(sb_writers#3){.+.+}, at: [<ffffffff81867bdf>] file_start_write include/linux/fs.h:2712 [inline]
(sb_writers#3){.+.+}, at: [<ffffffff81867bdf>] do_sendfile+0x84f/0xb30 fs/read_write.c:1440
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (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+0x64/0x260 fs/super.c:1342
sb_start_write include/linux/fs.h:1549 [inline]
mnt_want_write+0x3a/0xb0 fs/namespace.c:386
ovl_do_remove+0x67/0xb90 fs/overlayfs/dir.c:759
vfs_rmdir.part.0+0x144/0x390 fs/namei.c:3908
vfs_rmdir fs/namei.c:3893 [inline]
do_rmdir+0x334/0x3c0 fs/namei.c:3968
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
-> #2 (&ovl_i_mutex_dir_key[depth]#2){++++}:
down_read+0x36/0x80 kernel/locking/rwsem.c:24
inode_lock_shared include/linux/fs.h:729 [inline]
do_last fs/namei.c:3333 [inline]
path_openat+0x149b/0x2970 fs/namei.c:3569
do_filp_open+0x179/0x3c0 fs/namei.c:3603
do_open_execat+0xd3/0x450 fs/exec.c:849
do_execveat_common+0x711/0x1f30 fs/exec.c:1755
do_execve fs/exec.c:1860 [inline]
SYSC_execve fs/exec.c:1941 [inline]
SyS_execve+0x3b/0x50 fs/exec.c:1936
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
-> #1 (&sig->cred_guard_mutex){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
lock_trace fs/proc/base.c:407 [inline]
proc_pid_stack+0x13f/0x2f0 fs/proc/base.c:457
proc_single_show+0xe7/0x150 fs/proc/base.c:761
seq_read+0x4cf/0x1120 fs/seq_file.c:237
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3eb/0x5b0 fs/read_write.c:919
vfs_readv+0xc8/0x120 fs/read_write.c:981
do_preadv fs/read_write.c:1065 [inline]
SYSC_preadv fs/read_write.c:1115 [inline]
SyS_preadv+0x15a/0x200 fs/read_write.c:1110
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
-> #0 (&p->lock){+.+.}:
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
seq_read+0xba/0x1120 fs/seq_file.c:165
proc_reg_read+0xee/0x1a0 fs/proc/inode.c:217
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3eb/0x5b0 fs/read_write.c:919
vfs_readv+0xc8/0x120 fs/read_write.c:981
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x418/0x910 fs/splice.c:416
do_splice_to+0xfb/0x140 fs/splice.c:880
splice_direct_to_actor+0x207/0x730 fs/splice.c:952
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x47f/0xb30 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1502 [inline]
SyS_sendfile64+0xff/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
other info that might help us debug this:
Chain exists of:
&p->lock --> &ovl_i_mutex_dir_key[depth]#2 --> sb_writers#3
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sb_writers#3);
lock(&ovl_i_mutex_dir_key[depth]#2);
lock(sb_writers#3);
lock(&p->lock);
*** DEADLOCK ***
1 lock held by syz-executor.3/20011:
#0: (sb_writers#3){.+.+}, at: [<ffffffff81867bdf>] file_start_write include/linux/fs.h:2712 [inline]
#0: (sb_writers#3){.+.+}, at: [<ffffffff81867bdf>] do_sendfile+0x84f/0xb30 fs/read_write.c:1440
stack backtrace:
CPU: 1 PID: 20011 Comm: syz-executor.3 Not tainted 4.14.221-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
check_prev_add kernel/locking/lockdep.c:1905 [inline]
check_prevs_add kernel/locking/lockdep.c:2022 [inline]
validate_chain kernel/locking/lockdep.c:2464 [inline]
__lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
seq_read+0xba/0x1120 fs/seq_file.c:165
proc_reg_read+0xee/0x1a0 fs/proc/inode.c:217
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3eb/0x5b0 fs/read_write.c:919
vfs_readv+0xc8/0x120 fs/read_write.c:981
kernel_readv fs/splice.c:361 [inline]
default_file_splice_read+0x418/0x910 fs/splice.c:416
do_splice_to+0xfb/0x140 fs/splice.c:880
splice_direct_to_actor+0x207/0x730 fs/splice.c:952
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x47f/0xb30 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1502 [inline]
SyS_sendfile64+0xff/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x466019
RSP: 002b:00007f10f002e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 000000000056c0b0 RCX: 0000000000466019
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00000000004bd067 R08: 0000000000000000 R09: 0000000000000000
R10: 4000000000010046 R11: 0000000000000246 R12: 000000000056c0b0
R13: 00007ffcb785be8f R14: 00007f10f002e300 R15: 0000000000022000