======================================================
WARNING: possible circular locking dependency detected
5.6.0-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/3117 is trying to acquire lock:
ffff88809b233db8 (&p->lock){+.+.}-{3:3}, at: seq_read+0x66/0xd20 fs/seq_file.c:161
but task is already holding lock:
ffff88809a3b6450 (sb_writers#3){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2903 [inline]
ffff88809a3b6450 (sb_writers#3){.+.+}-{0:0}, at: do_sendfile+0x7dd/0xfd0 fs/read_write.c:1519
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write+0x14b/0x410 fs/super.c:1674
sb_start_write include/linux/fs.h:1650 [inline]
mnt_want_write+0x45/0x90 fs/namespace.c:354
ovl_create_object+0xb1/0x2b0 fs/overlayfs/dir.c:596
lookup_open fs/namei.c:3309 [inline]
do_last fs/namei.c:3401 [inline]
path_openat+0x2221/0x40f0 fs/namei.c:3607
do_filp_open+0x191/0x3a0 fs/namei.c:3637
do_sys_openat2+0x448/0x6c0 fs/open.c:1146
do_sys_open fs/open.c:1162 [inline]
ksys_open include/linux/syscalls.h:1386 [inline]
__do_sys_creat fs/open.c:1230 [inline]
__se_sys_creat fs/open.c:1228 [inline]
__x64_sys_creat+0xd3/0x100 fs/open.c:1228
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #2 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
down_read+0x36/0x50 kernel/locking/rwsem.c:1492
inode_lock_shared include/linux/fs.h:802 [inline]
do_last fs/namei.c:3400 [inline]
path_openat+0xbf2/0x40f0 fs/namei.c:3607
do_filp_open+0x191/0x3a0 fs/namei.c:3637
do_open_execat+0x101/0x5f0 fs/exec.c:860
open_exec+0x3c/0x50 fs/exec.c:892
load_script+0x6e5/0x880 fs/binfmt_script.c:141
search_binary_handler+0x17c/0x590 fs/exec.c:1688
exec_binprm fs/exec.c:1731 [inline]
__do_execve_file+0x1433/0x1b80 fs/exec.c:1851
do_execveat_common fs/exec.c:1897 [inline]
do_execveat fs/exec.c:1925 [inline]
__do_sys_execveat fs/exec.c:2001 [inline]
__se_sys_execveat fs/exec.c:1993 [inline]
__x64_sys_execveat+0xcf/0xe0 fs/exec.c:1993
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (&sig->cred_guard_mutex){+.+.}-{3:3}:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__mutex_lock_common+0x189/0x2fc0 kernel/locking/mutex.c:956
__mutex_lock kernel/locking/mutex.c:1103 [inline]
mutex_lock_killable_nested+0x1a/0x20 kernel/locking/mutex.c:1133
do_io_accounting fs/proc/base.c:2864 [inline]
proc_tgid_io_accounting+0x163/0x570 fs/proc/base.c:2913
proc_single_show+0xd5/0x160 fs/proc/base.c:758
seq_read+0x4aa/0xd20 fs/seq_file.c:229
do_loop_readv_writev fs/read_write.c:714 [inline]
do_iter_read+0x43e/0x550 fs/read_write.c:935
vfs_readv fs/read_write.c:1053 [inline]
do_preadv+0x17b/0x290 fs/read_write.c:1145
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&p->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:2515 [inline]
check_prevs_add kernel/locking/lockdep.c:2620 [inline]
validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237
__lock_acquire+0x116c/0x2b90 kernel/locking/lockdep.c:4344
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__mutex_lock_common+0x189/0x2fc0 kernel/locking/mutex.c:956
__mutex_lock kernel/locking/mutex.c:1103 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118
seq_read+0x66/0xd20 fs/seq_file.c:161
do_loop_readv_writev fs/read_write.c:714 [inline]
do_iter_read+0x43e/0x550 fs/read_write.c:935
vfs_readv+0xc2/0x120 fs/read_write.c:1053
kernel_readv fs/splice.c:365 [inline]
default_file_splice_read+0x579/0xa40 fs/splice.c:422
do_splice_to fs/splice.c:892 [inline]
splice_direct_to_actor+0x3c1/0xb40 fs/splice.c:971
do_splice_direct+0x201/0x340 fs/splice.c:1080
do_sendfile+0x809/0xfd0 fs/read_write.c:1520
__do_sys_sendfile64 fs/read_write.c:1581 [inline]
__se_sys_sendfile64 fs/read_write.c:1567 [inline]
__x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1567
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
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] --> sb_writers#3
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sb_writers#3);
lock(&ovl_i_mutex_dir_key[depth]);
lock(sb_writers#3);
lock(&p->lock);
*** DEADLOCK ***
1 lock held by syz-executor.1/3117:
#0: ffff88809a3b6450 (sb_writers#3){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2903 [inline]
#0: ffff88809a3b6450 (sb_writers#3){.+.+}-{0:0}, at: do_sendfile+0x7dd/0xfd0 fs/read_write.c:1519
stack backtrace:
CPU: 0 PID: 3117 Comm: syz-executor.1 Not tainted 5.6.0-syzkaller #0
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+0x1e9/0x30e lib/dump_stack.c:118
print_circular_bug+0xc72/0xea0 kernel/locking/lockdep.c:1722
check_noncircular+0x1fb/0x3a0 kernel/locking/lockdep.c:1846
check_prev_add kernel/locking/lockdep.c:2515 [inline]
check_prevs_add kernel/locking/lockdep.c:2620 [inline]
validate_chain+0x1b09/0x8920 kernel/locking/lockdep.c:3237
__lock_acquire+0x116c/0x2b90 kernel/locking/lockdep.c:4344
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__mutex_lock_common+0x189/0x2fc0 kernel/locking/mutex.c:956
__mutex_lock kernel/locking/mutex.c:1103 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118
seq_read+0x66/0xd20 fs/seq_file.c:161
do_loop_readv_writev fs/read_write.c:714 [inline]
do_iter_read+0x43e/0x550 fs/read_write.c:935
vfs_readv+0xc2/0x120 fs/read_write.c:1053
kernel_readv fs/splice.c:365 [inline]
default_file_splice_read+0x579/0xa40 fs/splice.c:422
do_splice_to fs/splice.c:892 [inline]
splice_direct_to_actor+0x3c1/0xb40 fs/splice.c:971
do_splice_direct+0x201/0x340 fs/splice.c:1080
do_sendfile+0x809/0xfd0 fs/read_write.c:1520
__do_sys_sendfile64 fs/read_write.c:1581 [inline]
__se_sys_sendfile64 fs/read_write.c:1567 [inline]
__x64_sys_sendfile64+0x164/0x1a0 fs/read_write.c:1567
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c849
Code: ad b6 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 b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3341cdac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f3341cdb6d4 RCX: 000000000045c849
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000007
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000209 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d4 R14: 00000000004cb786 R15: 000000000076bf0c