INFO: task hung in ext4_mb_initialize_context

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 6d0c334a Linux 4.14.164
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1469c821e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=8b0a5fc97f3338bc
dashboard link: https://syzkaller.appspot.com/bug?extid=2605a8721b8ce7bef61b
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+2605a8...@syzkaller.appspotmail.com

INFO: task syz-executor.3:15658 blocked for more than 140 seconds.
Not tainted 4.14.164-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D27200 15658 11502 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
ext4_mb_group_or_file fs/ext4/mballoc.c:4245 [inline]
ext4_mb_initialize_context+0x7ab/0xba0 fs/ext4/mballoc.c:4288
ext4_mb_new_blocks+0x52f/0x3b30 fs/ext4/mballoc.c:4561
ext4_alloc_branch fs/ext4/indirect.c:335 [inline]
ext4_ind_map_blocks+0x1296/0x23a0 fs/ext4/indirect.c:619
ext4_map_blocks+0xd61/0x17c0 fs/ext4/inode.c:646
_ext4_get_block+0x1a0/0x590 fs/ext4/inode.c:797
ext4_get_block_trans+0x145/0x230 fs/ext4/inode.c:858
ext4_dio_get_block+0x6f/0xb0 fs/ext4/inode.c:875
get_more_blocks fs/direct-io.c:718 [inline]
do_direct_IO fs/direct-io.c:1003 [inline]
do_blockdev_direct_IO+0x1f73/0x9130 fs/direct-io.c:1336
__blockdev_direct_IO+0xa1/0xca fs/direct-io.c:1422
ext4_direct_IO_write fs/ext4/inode.c:3712 [inline]
ext4_direct_IO+0x7c1/0x18f0 fs/ext4/inode.c:3848
generic_file_direct_write+0x1e7/0x430 mm/filemap.c:2950
__generic_file_write_iter+0x2bc/0x5b0 mm/filemap.c:3129
ext4_file_write_iter+0x2ac/0xe90 fs/ext4/file.c:268
call_write_iter include/linux/fs.h:1777 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x4a7/0x6b0 fs/read_write.c:482
vfs_write+0x198/0x500 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xfd/0x230 fs/read_write.c:582
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45af49
RSP: 002b:00007fd8df293c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045af49
RDX: 000000010000000d RSI: 0000000020000000 RDI: 0000000000000009
RBP: 000000000075c118 R08: 0000000000000000 R09: 0000000000000000


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[syzbot]

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