[syzbot] possible deadlock in lock_two_nondirectories

From: syzbot
Date: Thu Sep 22 2022 - 18:25:33 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 38eddeedbbea Merge tag 'io_uring-6.0-2022-09-18' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134eed64880000
kernel config: https://syzkaller.appspot.com/x/.config?x=98a30118ec9215e9
dashboard link: https://syzkaller.appspot.com/bug?extid=fa80832503dc44cfd65d
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fa80832503dc44cfd65d@xxxxxxxxxxxxxxxxxxxxxxxxx

overlayfs: fs on './file0' does not support file handles, falling back to index=off,nfs_export=off.
======================================================
WARNING: possible circular locking dependency detected
6.0.0-rc5-syzkaller-00097-g38eddeedbbea #0 Not tainted
------------------------------------------------------
syz-executor.5/15945 is trying to acquire lock:
ffff88807faf5e48 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
ffff88807faf5e48 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}, at: lock_two_nondirectories+0xd1/0x110 fs/inode.c:1124

but task is already holding lock:
ffff8880300bb628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff8880300bb628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xec/0x110 fs/inode.c:1122

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
down_read+0x98/0x450 kernel/locking/rwsem.c:1499
inode_lock_shared include/linux/fs.h:766 [inline]
ext4_bmap+0x4e/0x460 fs/ext4/inode.c:3157
bmap+0xaa/0x120 fs/inode.c:1799
jbd2_journal_bmap+0xa8/0x180 fs/jbd2/journal.c:971
__jbd2_journal_erase fs/jbd2/journal.c:1784 [inline]
jbd2_journal_flush+0x84f/0xc00 fs/jbd2/journal.c:2490
ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline]
__ext4_ioctl+0x28fd/0x4ab0 fs/ext4/ioctl.c:1586
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
mutex_lock_io_nested+0x13f/0x1190 kernel/locking/mutex.c:833
__jbd2_log_wait_for_space+0x234/0x460 fs/jbd2/checkpoint.c:110
add_transaction_credits+0xa2d/0xb70 fs/jbd2/transaction.c:298
start_this_handle+0x3ae/0x14a0 fs/jbd2/transaction.c:422
jbd2__journal_start+0x38c/0x910 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x3a3/0x490 fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_evict_inode+0x990/0x1d40 fs/ext4/inode.c:251
evict+0x2ed/0x6b0 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput.part.0+0x55d/0x810 fs/inode.c:1774
iput+0x58/0x70 fs/inode.c:1764
d_delete_notify include/linux/fsnotify.h:261 [inline]
vfs_rmdir.part.0+0x496/0x5a0 fs/namei.c:4111
vfs_rmdir fs/namei.c:4083 [inline]
do_rmdir+0x3a6/0x430 fs/namei.c:4159
__do_sys_unlinkat fs/namei.c:4339 [inline]
__se_sys_unlinkat fs/namei.c:4333 [inline]
__x64_sys_unlinkat+0xeb/0x130 fs/namei.c:4333
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (sb_internal){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1826 [inline]
sb_start_intwrite include/linux/fs.h:1948 [inline]
ext4_evict_inode+0x11de/0x1d40 fs/ext4/inode.c:240
evict+0x2ed/0x6b0 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput.part.0+0x55d/0x810 fs/inode.c:1774
iput+0x58/0x70 fs/inode.c:1764
ext4_rename+0x1411/0x2650 fs/ext4/namei.c:3985
ext4_rename2+0x1c3/0x270 fs/ext4/namei.c:4164
vfs_rename+0x115e/0x1a90 fs/namei.c:4756
do_renameat2+0xb5e/0xc80 fs/namei.c:4907
__do_sys_renameat2 fs/namei.c:4940 [inline]
__se_sys_renameat2 fs/namei.c:4937 [inline]
__x64_sys_renameat2+0xe4/0x120 fs/namei.c:4937
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sb->s_type->i_mutex_key#8/4){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5053
lock_acquire kernel/locking/lockdep.c:5666 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
down_write_nested+0x94/0x150 kernel/locking/rwsem.c:1662
inode_lock_nested include/linux/fs.h:791 [inline]
lock_two_nondirectories+0xd1/0x110 fs/inode.c:1124
vfs_rename+0xc14/0x1a90 fs/namei.c:4726
ovl_do_rename fs/overlayfs/overlayfs.h:297 [inline]
ovl_rename+0xe33/0x1770 fs/overlayfs/dir.c:1257
vfs_rename+0x115e/0x1a90 fs/namei.c:4756
do_renameat2+0xb5e/0xc80 fs/namei.c:4907
__do_sys_rename fs/namei.c:4953 [inline]
__se_sys_rename fs/namei.c:4951 [inline]
__x64_sys_rename+0x7d/0xa0 fs/namei.c:4951
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
&sb->s_type->i_mutex_key#8/4 --> &journal->j_checkpoint_mutex --> &sb->s_type->i_mutex_key#8

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&sb->s_type->i_mutex_key#8);
lock(&journal->j_checkpoint_mutex);
lock(&sb->s_type->i_mutex_key#8);
lock(&sb->s_type->i_mutex_key#8/4);

*** DEADLOCK ***

12 locks held by syz-executor.5/15945:
#0: ffff888040a1e460 (sb_writers#14){.+.+}-{0:0}, at: do_renameat2+0x37b/0xc80 fs/namei.c:4843
#1: ffff888040a1e748 (&type->s_vfs_rename_key#2){+.+.}-{3:3}, at: lock_rename+0x54/0x280 fs/namei.c:2994
#2: ffff88803037b030 (&ovl_i_mutex_dir_key[depth]#2/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#2: ffff88803037b030 (&ovl_i_mutex_dir_key[depth]#2/1){+.+.}-{3:3}, at: lock_rename+0x132/0x280 fs/namei.c:3005
#3: ffff88803037a480 (&ovl_i_mutex_dir_key[depth]#2/2){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#3: ffff88803037a480 (&ovl_i_mutex_dir_key[depth]#2/2){+.+.}-{3:3}, at: lock_rename+0x166/0x280 fs/namei.c:3006
#4: ffff88803037eaa0 (&ovl_i_mutex_key[depth]#2){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#4: ffff88803037eaa0 (&ovl_i_mutex_key[depth]#2){+.+.}-{3:3}, at: lock_two_nondirectories+0xec/0x110 fs/inode.c:1122
#5: ffff88803037f078 (&ovl_i_mutex_key[depth]#2/4){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#5: ffff88803037f078 (&ovl_i_mutex_key[depth]#2/4){+.+.}-{3:3}, at: lock_two_nondirectories+0xd1/0x110 fs/inode.c:1124
#6: ffff88807e942460 (sb_writers#4){.+.+}-{0:0}, at: ovl_rename+0x25f/0x1770 fs/overlayfs/dir.c:1137
#7: ffff88803037ee60 (&ovl_i_lock_key[depth]#2){+.+.}-{3:3}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:499 [inline]
#7: ffff88803037ee60 (&ovl_i_lock_key[depth]#2){+.+.}-{3:3}, at: ovl_nlink_start+0xe1/0x2e0 fs/overlayfs/util.c:915
#8: ffff88807e942748 (&type->s_vfs_rename_key){+.+.}-{3:3}, at: lock_rename+0x54/0x280 fs/namei.c:2994
#9: ffff8880300bc030 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#9: ffff8880300bc030 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: lock_rename+0x132/0x280 fs/namei.c:3005
#10: ffff88801e3e3628 (&type->i_mutex_dir_key#3/2){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#10: ffff88801e3e3628 (&type->i_mutex_dir_key#3/2){+.+.}-{3:3}, at: lock_rename+0x166/0x280 fs/namei.c:3006
#11: ffff8880300bb628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#11: ffff8880300bb628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: lock_two_nondirectories+0xec/0x110 fs/inode.c:1122

stack backtrace:
CPU: 1 PID: 15945 Comm: syz-executor.5 Not tainted 6.0.0-rc5-syzkaller-00097-g38eddeedbbea #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5053
lock_acquire kernel/locking/lockdep.c:5666 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
down_write_nested+0x94/0x150 kernel/locking/rwsem.c:1662
inode_lock_nested include/linux/fs.h:791 [inline]
lock_two_nondirectories+0xd1/0x110 fs/inode.c:1124
vfs_rename+0xc14/0x1a90 fs/namei.c:4726
ovl_do_rename fs/overlayfs/overlayfs.h:297 [inline]
ovl_rename+0xe33/0x1770 fs/overlayfs/dir.c:1257
vfs_rename+0x115e/0x1a90 fs/namei.c:4756
do_renameat2+0xb5e/0xc80 fs/namei.c:4907
__do_sys_rename fs/namei.c:4953 [inline]
__se_sys_rename fs/namei.c:4951 [inline]
__x64_sys_rename+0x7d/0xa0 fs/namei.c:4951
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f693c089409
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f693d1f1168 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f693c19bf80 RCX: 00007f693c089409
RDX: 0000000000000000 RSI: 0000000020000440 RDI: 0000000020000100
RBP: 00007f693c0e4367 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdde820edf R14: 00007f693d1f1300 R15: 0000000000022000
</TASK>

---
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