[syzbot] possible deadlock in __jbd2_log_wait_for_space

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ca688bff68bc Add linux-next specific files for 20220808
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1376e68e080000
kernel config: https://syzkaller.appspot.com/x/.config?x=4c20e006003cdecb
dashboard link: https://syzkaller.appspot.com/bug?extid=fa1bbda326271b8808c9
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+fa1bbd...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.19.0-next-20220808-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/19227 is trying to acquire lock:
ffff8880272aa3f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: __jbd2_log_wait_for_space+0x234/0x460 fs/jbd2/checkpoint.c:110

but task is already holding lock:
ffff888076d40e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:761 [inline]
ffff888076d40e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_dio_write_iter fs/ext4/file.c:510 [inline]
ffff888076d40e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_file_write_iter+0xbea/0x1660 fs/ext4/file.c:677

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&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:771 [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

-> #0 (&journal->j_checkpoint_mutex){+.+.}-{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
__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_handle_inode_extension+0x312/0x870 fs/ext4/file.c:325
ext4_dio_write_iter fs/ext4/file.c:573 [inline]
ext4_file_write_iter+0x12df/0x1660 fs/ext4/file.c:677
call_write_iter include/linux/fs.h:2192 [inline]
do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:729
do_iter_write+0x182/0x700 fs/read_write.c:855
vfs_iter_write+0x70/0xa0 fs/read_write.c:896
iter_file_splice_write+0x741/0xc90 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0x110/0x180 fs/splice.c:931
splice_direct_to_actor+0x331/0x8a0 fs/splice.c:886
do_splice_direct+0x1a7/0x270 fs/splice.c:974
do_sendfile+0xb19/0x1270 fs/read_write.c:1249
__do_sys_sendfile64 fs/read_write.c:1317 [inline]
__se_sys_sendfile64 fs/read_write.c:1303 [inline]
__x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1303
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:

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(&journal->j_checkpoint_mutex);

*** DEADLOCK ***

2 locks held by syz-executor.4/19227:
#0: ffff88801c596460 (sb_writers#4){.+.+}-{0:0}, at: __do_sys_sendfile64 fs/read_write.c:1317 [inline]
#0: ffff88801c596460 (sb_writers#4){.+.+}-{0:0}, at: __se_sys_sendfile64 fs/read_write.c:1303 [inline]
#0: ffff88801c596460 (sb_writers#4){.+.+}-{0:0}, at: __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1303
#1: ffff888076d40e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:761 [inline]
#1: ffff888076d40e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_dio_write_iter fs/ext4/file.c:510 [inline]
#1: ffff888076d40e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_file_write_iter+0xbea/0x1660 fs/ext4/file.c:677

stack backtrace:
CPU: 1 PID: 19227 Comm: syz-executor.4 Not tainted 5.19.0-next-20220808-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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
__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_handle_inode_extension+0x312/0x870 fs/ext4/file.c:325
ext4_dio_write_iter fs/ext4/file.c:573 [inline]
ext4_file_write_iter+0x12df/0x1660 fs/ext4/file.c:677
call_write_iter include/linux/fs.h:2192 [inline]
do_iter_readv_writev+0x20b/0x3b0 fs/read_write.c:729
do_iter_write+0x182/0x700 fs/read_write.c:855
vfs_iter_write+0x70/0xa0 fs/read_write.c:896
iter_file_splice_write+0x741/0xc90 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0x110/0x180 fs/splice.c:931
splice_direct_to_actor+0x331/0x8a0 fs/splice.c:886
do_splice_direct+0x1a7/0x270 fs/splice.c:974
do_sendfile+0xb19/0x1270 fs/read_write.c:1249
__do_sys_sendfile64 fs/read_write.c:1317 [inline]
__se_sys_sendfile64 fs/read_write.c:1303 [inline]
__x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1303
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: 0033:0x7f0ff2c89279
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:00007f0ff3d23168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f0ff2d9bf80 RCX: 00007f0ff2c89279
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004
RBP: 00007f0ff2ce3189 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000f03b2900 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcbe563eef R14: 00007f0ff3d23300 R15: 0000000000022000
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 15f3bff12cf6 Add linux-next specific files for 20221116
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1370fb65880000
kernel config: https://syzkaller.appspot.com/x/.config?x=ec2a1d4f50866178

dashboard link: https://syzkaller.appspot.com/bug?extid=fa1bbda326271b8808c9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=114241dd880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14c2f42d880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b67307c8c3c9/disk-15f3bff1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/956c7b56c5c1/vmlinux-15f3bff1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/505ae2f65529/bzImage-15f3bff1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fa1bbd...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected

6.1.0-rc5-next-20221116-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor164/5304 is trying to acquire lock:
ffff88814baea3f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: __jbd2_log_wait_for_space+0x238/0x460 fs/jbd2/checkpoint.c:110

but task is already holding lock:

ffff888065608e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
ffff888065608e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_unlink+0xd9/0x930 fs/namei.c:4240

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#8){++++}-{3:3}:

down_read+0x9c/0x450 kernel/locking/rwsem.c:1509
inode_lock_shared include/linux/fs.h:766 [inline]
ext4_bmap+0x52/0x470 fs/ext4/inode.c:3164
bmap+0xae/0x120 fs/inode.c:1798
jbd2_journal_bmap+0xac/0x180 fs/jbd2/journal.c:977
__jbd2_journal_erase fs/jbd2/journal.c:1789 [inline]
jbd2_journal_flush+0x853/0xc00 fs/jbd2/journal.c:2492
ext4_ioctl_checkpoint fs/ext4/ioctl.c:1081 [inline]
__ext4_ioctl+0xae8/0x4d60 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+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:

check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
mutex_lock_io_nested+0x143/0x11a0 kernel/locking/mutex.c:833
__jbd2_log_wait_for_space+0x238/0x460 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+0x39d/0x9b0 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x421/0x530 fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_unlink+0x32b/0xae0 fs/ext4/namei.c:3284
vfs_unlink+0x355/0x930 fs/namei.c:4251
do_unlinkat+0x3b7/0x640 fs/namei.c:4319
__do_sys_unlink fs/namei.c:4367 [inline]
__se_sys_unlink fs/namei.c:4365 [inline]
__x64_sys_unlink+0xca/0x110 fs/namei.c:4365
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

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(&journal->j_checkpoint_mutex);

*** DEADLOCK ***

3 locks held by syz-executor164/5304:
#0: ffff88814bae6460 (sb_writers#4){.+.+}-{0:0}, at: do_unlinkat+0x183/0x640 fs/namei.c:4298
#1: ffff888076c1d440 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#1: ffff888076c1d440 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0x270/0x640 fs/namei.c:4302
#2: ffff888065608e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
#2: ffff888065608e08 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_unlink+0xd9/0x930 fs/namei.c:4240

stack backtrace:
CPU: 1 PID: 5304 Comm: syz-executor164 Not tainted 6.1.0-rc5-next-20221116-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]

dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
mutex_lock_io_nested+0x143/0x11a0 kernel/locking/mutex.c:833
__jbd2_log_wait_for_space+0x238/0x460 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+0x39d/0x9b0 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x421/0x530 fs/ext4/ext4_jbd2.c:105
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_unlink+0x32b/0xae0 fs/ext4/namei.c:3284
vfs_unlink+0x355/0x930 fs/namei.c:4251
do_unlinkat+0x3b7/0x640 fs/namei.c:4319
__do_sys_unlink fs/namei.c:4367 [inline]
__se_sys_unlink fs/namei.c:4365 [inline]
__x64_sys_unlink+0xca/0x110 fs/namei.c:4365
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f3a0088bff7
Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 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:00007ffe6d2c0f28 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3a0088bff7
RDX: 00007ffe6d2c0f50 RSI: 00007ffe6d2c0f50 RDI: 00007ffe6d2c0fe0
RBP: 00007ffe6d2c0fe0 R08: 0000000000000001 R09: 00007ffe6d2c0dc0
R10: 0000555555f9e683 R11: 0000000000000206 R12: 00007ffe6d2c20a0
R13: 0000555555f9e5f0 R14: 00007ffe6d2c0f50 R15: 431bde82d7b634db
</TASK>

[Hillf Danton]

On Fri, 18 Nov 2022 20:50:39 -0800

> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: 15f3bff12cf6 Add linux-next specific files for 20221116
> git tree: linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1370fb65880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ec2a1d4f50866178
> dashboard link: https://syzkaller.appspot.com/bug?extid=fa1bbda326271b8808c9
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=114241dd880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14c2f42d880000

Replace inode lock with EXT4_I(inode)->xattr_sem

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 15f3bff12cf6

--- x/fs/ext4/inode.c
+++ i/fs/ext4/inode.c
@@ -3161,7 +3161,7 @@ static sector_t ext4_bmap(struct address
sector_t ret = 0;
int err;

- inode_lock_shared(inode);
+ down_read(&EXT4_I(inode)->xattr_sem);
/*
* We can get here for an inline file via the FIBMAP ioctl
*/
@@ -3211,7 +3211,7 @@ static sector_t ext4_bmap(struct address
ret = iomap_bmap(mapping, block, &ext4_iomap_ops);

out:
- inode_unlock_shared(inode);
+ up_read(&EXT4_I(inode)->xattr_sem);
return ret;
}

--

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: rcu detected stall in corrupted

rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { P5776 } 2683 jiffies s: 2765 root: 0x0/T
rcu: blocking rcu_node structures (internal RCU debug):


Tested on:

commit: 15f3bff1 Add linux-next specific files for 20221116
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=130bea4e880000

kernel config: https://syzkaller.appspot.com/x/.config?x=ec2a1d4f50866178
dashboard link: https://syzkaller.appspot.com/bug?extid=fa1bbda326271b8808c9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=15922a21880000

[Hillf Danton]

On Fri, 18 Nov 2022 20:50:39 -0800

> HEAD commit: 15f3bff12cf6 Add linux-next specific files for 20221116
> git tree: linux-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14c2f42d880000

Replace inode lock with EXT4_I(inode)->xattr_sem

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

--- x/fs/ext4/inode.c
+++ i/fs/ext4/inode.c
@@ -3239,7 +3239,7 @@ static sector_t ext4_bmap(struct address

sector_t ret = 0;
int err;

- inode_lock_shared(inode);
+ down_read(&EXT4_I(inode)->xattr_sem);
/*
* We can get here for an inline file via the FIBMAP ioctl
*/

@@ -3289,7 +3289,7 @@ static sector_t ext4_bmap(struct address

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+fa1bbd...@syzkaller.appspotmail.com

Tested on:

commit: 65aca32e Merge tag 'mm-hotfixes-stable-2023-03-24-17-0..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=161fa54dc80000
kernel config: https://syzkaller.appspot.com/x/.config?x=2deb1e902f2b9c24
dashboard link: https://syzkaller.appspot.com/bug?extid=fa1bbda326271b8808c9
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=1760dbb1c80000

Note: testing is done by a robot and is best-effort only.

[Theodore Ts'o]

#syz fix: ext4, jbd2: add an optimized bmap for the journal inode