Hello,
syzbot found the following issue on:
HEAD commit: 09e5c48fea17 Merge tag 'ceph-for-6.8-rc8' of https://githu..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=130a9a3e180000
kernel config: https://syzkaller.appspot.com/x/.config?x=44c92d6f247776b0
dashboard link: https://syzkaller.appspot.com/bug?extid=e525d9be15a106e48379
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/be1396cce3c5/disk-09e5c48f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cd84fbdb0969/vmlinux-09e5c48f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/46bf297bd50b/bzImage-09e5c48f.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc7-syzkaller-00231-g09e5c48fea17 #0 Not tainted
------------------------------------------------------
syz-executor.2/10894 is trying to acquire lock:
ffff8880434f8468 (&pipe->mutex/1){+.+.}-{3:3}, at: iter_file_splice_write+0x335/0x14e0 fs/splice.c:687
but task is already holding lock:
ffff88801e194420 (sb_writers#4){.+.+}-{0:0}, at: do_splice+0xcf0/0x1880 fs/splice.c:1353
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (sb_writers#4){.+.+}-{0:0}:
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1641 [inline]
sb_start_write+0x4d/0x1c0 include/linux/fs.h:1777
mnt_want_write+0x3f/0x90 fs/namespace.c:409
ovl_create_object+0x13b/0x370 fs/overlayfs/dir.c:629
lookup_open fs/namei.c:3500 [inline]
open_last_lookups fs/namei.c:3569 [inline]
path_openat+0x1424/0x3240 fs/namei.c:3799
do_filp_open+0x234/0x490 fs/namei.c:3829
do_sys_openat2+0x13e/0x1d0 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1430
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
-> #3 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}:
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526
inode_lock_shared include/linux/fs.h:814 [inline]
lookup_slow+0x45/0x70 fs/namei.c:1709
walk_component+0x2e1/0x410 fs/namei.c:2005
lookup_last fs/namei.c:2462 [inline]
path_lookupat+0x16f/0x450 fs/namei.c:2486
filename_lookup+0x255/0x610 fs/namei.c:2515
kern_path+0x35/0x50 fs/namei.c:2623
lookup_bdev+0xc5/0x290 block/bdev.c:1014
resume_store+0x1a0/0x710 kernel/power/hibernate.c:1183
kernfs_fop_write_iter+0x3a4/0x500 fs/kernfs/file.c:334
call_write_iter include/linux/fs.h:2087 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa81/0xcb0 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
-> #2 (&of->mutex){+.+.}-{3:3}:
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154
seq_read_iter+0x3d0/0xd60 fs/seq_file.c:225
call_read_iter include/linux/fs.h:2081 [inline]
new_sync_read fs/read_write.c:395 [inline]
vfs_read+0x978/0xb70 fs/read_write.c:476
ksys_read+0x1a0/0x2c0 fs/read_write.c:619
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
-> #1 (&p->lock){+.+.}-{3:3}:
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
seq_read_iter+0xb7/0xd60 fs/seq_file.c:182
proc_reg_read_iter+0x1c3/0x290 fs/proc/inode.c:299
call_read_iter include/linux/fs.h:2081 [inline]
copy_splice_read+0x661/0xb60 fs/splice.c:365
do_splice_read fs/splice.c:985 [inline]
splice_file_to_pipe+0x299/0x500 fs/splice.c:1295
do_sendfile+0x515/0xdc0 fs/read_write.c:1301
__do_sys_sendfile64 fs/read_write.c:1356 [inline]
__se_sys_sendfile64+0x100/0x1e0 fs/read_write.c:1348
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
-> #0 (&pipe->mutex/1){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869
__lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
iter_file_splice_write+0x335/0x14e0 fs/splice.c:687
do_splice_from fs/splice.c:941 [inline]
do_splice+0xd77/0x1880 fs/splice.c:1354
__do_splice fs/splice.c:1436 [inline]
__do_sys_splice fs/splice.c:1652 [inline]
__se_sys_splice+0x331/0x4a0 fs/splice.c:1634
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
other info that might help us debug this:
Chain exists of:
&pipe->mutex/1 --> &ovl_i_mutex_dir_key[depth] --> sb_writers#4
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
rlock(sb_writers#4);
lock(&ovl_i_mutex_dir_key[depth]);
lock(sb_writers#4);
lock(&pipe->mutex/1);
*** DEADLOCK ***
1 lock held by syz-executor.2/10894:
#0: ffff88801e194420 (sb_writers#4){.+.+}-{0:0}, at: do_splice+0xcf0/0x1880 fs/splice.c:1353
stack backtrace:
CPU: 1 PID: 10894 Comm: syz-executor.2 Not tainted 6.8.0-rc7-syzkaller-00231-g09e5c48fea17 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869
__lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
iter_file_splice_write+0x335/0x14e0 fs/splice.c:687
do_splice_from fs/splice.c:941 [inline]
do_splice+0xd77/0x1880 fs/splice.c:1354
__do_splice fs/splice.c:1436 [inline]
__do_sys_splice fs/splice.c:1652 [inline]
__se_sys_splice+0x331/0x4a0 fs/splice.c:1634
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7fa65fa7dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa6608b00c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007fa65fbabf80 RCX: 00007fa65fa7dda9
RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fa65faca47a R08: 0000000000000009 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fa65fbabf80 R15: 00007ffc7c0d55f8
</TASK>
---
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On Thu, 14 Mar 2024 at 00:10, syzbot
<[email protected]> wrote:
> -> #3 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}:
> lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
> down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526
> inode_lock_shared include/linux/fs.h:814 [inline]
> lookup_slow+0x45/0x70 fs/namei.c:1709
> walk_component+0x2e1/0x410 fs/namei.c:2005
> lookup_last fs/namei.c:2462 [inline]
> path_lookupat+0x16f/0x450 fs/namei.c:2486
> filename_lookup+0x255/0x610 fs/namei.c:2515
> kern_path+0x35/0x50 fs/namei.c:2623
This is what ultimately closes the locking loop: doing path lookup
(taking directory i_mutex) with kernfs of->mutex held.
#syz dup possible deadlock in seq_read_iter (3)
Thanks,
Miklos