[v6.1] possible deadlock in ext4_evict_inode (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c6114c845984 Linux 6.1.65
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14c84186e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=61e0c4a5fbb36a13
dashboard link: https://syzkaller.appspot.com/bug?extid=880b57274899b225d178
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/f761cbc53791/disk-c6114c84.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d6a6e4496af6/vmlinux-c6114c84.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f4794a58f735/bzImage-c6114c84.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+880b57...@syzkaller.appspotmail.com

EXT4-fs (loop4): mounted filesystem without journal. Quota mode: writeback.
ext4 filesystem being mounted at /root/syzkaller-testdir2273581239/syzkaller.yYAEnL/1740/file1 supports timestamps until 2038 (0x7fffffff)
======================================================
WARNING: possible circular locking dependency detected
6.1.65-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/30736 is trying to acquire lock:
ffff88801ea8e650 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1875 [inline]
ffff88801ea8e650 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1997 [inline]
ffff88801ea8e650 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x46d/0x1150 fs/ext4/inode.c:240

but task is already holding lock:
ffff88801ea88b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x314/0x12f0 fs/ext4/migrate.c:437

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&sbi->s_writepages_rwsem){++++}-{0:0}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
ext4_writepages+0x1e5/0x3de0 fs/ext4/inode.c:2703
do_writepages+0x3a2/0x670 mm/page-writeback.c:2469
filemap_fdatawrite_wbc+0x121/0x180 mm/filemap.c:388
__filemap_fdatawrite_range mm/filemap.c:421 [inline]
filemap_write_and_wait_range+0x1a4/0x290 mm/filemap.c:674
__iomap_dio_rw+0xb56/0x2140 fs/iomap/direct-io.c:573
iomap_dio_rw+0x42/0xa0 fs/iomap/direct-io.c:690
ext4_dio_read_iter fs/ext4/file.c:94 [inline]
ext4_file_read_iter+0x50b/0x660 fs/ext4/file.c:145
call_read_iter include/linux/fs.h:2242 [inline]
generic_file_splice_read+0x23c/0x630 fs/splice.c:309
do_splice_to fs/splice.c:793 [inline]
splice_direct_to_actor+0x408/0xbd0 fs/splice.c:865
do_splice_direct+0x27f/0x3c0 fs/splice.c:974
do_sendfile+0x61c/0xff0 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64+0x178/0x1e0 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
down_read+0xad/0xa30 kernel/locking/rwsem.c:1520
inode_lock_shared include/linux/fs.h:766 [inline]
ext4_bmap+0x4b/0x410 fs/ext4/inode.c:3176
bmap+0xa1/0xd0 fs/inode.c:1840
jbd2_journal_bmap fs/jbd2/journal.c:977 [inline]
__jbd2_journal_erase fs/jbd2/journal.c:1789 [inline]
jbd2_journal_flush+0x5b5/0xc40 fs/jbd2/journal.c:2492
ext4_ioctl_checkpoint fs/ext4/ioctl.c:1086 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1594 [inline]
ext4_ioctl+0x3986/0x5f60 fs/ext4/ioctl.c:1614
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
mutex_lock_io_nested+0x134/0xab0 kernel/locking/mutex.c:833
__jbd2_log_wait_for_space+0x213/0x760 fs/jbd2/checkpoint.c:71
add_transaction_credits fs/jbd2/transaction.c:298 [inline]
start_this_handle+0x1040/0x21b0 fs/jbd2/transaction.c:422
jbd2__journal_start+0x2d1/0x5c0 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x19b/0x410 fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_evict_inode+0x8dc/0x1150 fs/ext4/inode.c:251
evict+0x2a4/0x620 fs/inode.c:664
do_unlinkat+0x503/0x820 fs/namei.c:4328
__do_sys_unlink fs/namei.c:4369 [inline]
__se_sys_unlink fs/namei.c:4367 [inline]
__x64_sys_unlink+0x45/0x50 fs/namei.c:4367
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (sb_internal){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
__sb_start_write include/linux/fs.h:1875 [inline]
sb_start_intwrite include/linux/fs.h:1997 [inline]
ext4_evict_inode+0x46d/0x1150 fs/ext4/inode.c:240
evict+0x2a4/0x620 fs/inode.c:664
ext4_ext_migrate+0x100b/0x12f0 fs/ext4/migrate.c:587
__ext4_ioctl fs/ext4/ioctl.c:1396 [inline]
ext4_ioctl+0x1dc6/0x5f60 fs/ext4/ioctl.c:1614
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/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_internal --> &sb->s_type->i_mutex_key#8 --> &sbi->s_writepages_rwsem

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&sbi->s_writepages_rwsem);
lock(&sb->s_type->i_mutex_key#8);
lock(&sbi->s_writepages_rwsem);
lock(sb_internal);

*** DEADLOCK ***

3 locks held by syz-executor.4/30736:
#0: ffff88801ea8e460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
#1: ffff88808e644030 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#1: ffff88808e644030 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: __ext4_ioctl fs/ext4/ioctl.c:1395 [inline]
#1: ffff88808e644030 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_ioctl+0x1dbe/0x5f60 fs/ext4/ioctl.c:1614
#2: ffff88801ea88b98 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_ext_migrate+0x314/0x12f0 fs/ext4/migrate.c:437

stack backtrace:
CPU: 0 PID: 30736 Comm: syz-executor.4 Not tainted 6.1.65-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
check_prev_add kernel/locking/lockdep.c:3090 [inline]
check_prevs_add kernel/locking/lockdep.c:3209 [inline]
validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
percpu_down_read+0x44/0x1a0 include/linux/percpu-rwsem.h:51
__sb_start_write include/linux/fs.h:1875 [inline]
sb_start_intwrite include/linux/fs.h:1997 [inline]
ext4_evict_inode+0x46d/0x1150 fs/ext4/inode.c:240
evict+0x2a4/0x620 fs/inode.c:664
ext4_ext_migrate+0x100b/0x12f0 fs/ext4/migrate.c:587
__ext4_ioctl fs/ext4/ioctl.c:1396 [inline]
ext4_ioctl+0x1dc6/0x5f60 fs/ext4/ioctl.c:1614
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f69e4e7cae9
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:00007f69e5c070c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f69e4f9bf80 RCX: 00007f69e4e7cae9
RDX: 0000000000000000 RSI: 0000000000006609 RDI: 0000000000000005
RBP: 00007f69e4ec847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f69e4f9bf80 R15: 00007fffb91bca98
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.