INFO: task hung in vfs_setxattr

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: cec36153 ANDROID: Makefile: Properly resolve 4.14.112 merge
git tree: android-4.14
console output: https://syzkaller.appspot.com/x/log.txt?x=13903447200000
kernel config: https://syzkaller.appspot.com/x/.config?x=35cf872406d24dee
dashboard link: https://syzkaller.appspot.com/bug?extid=d7733b47586629a22411
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+d7733b...@syzkaller.appspotmail.com

INFO: task syz-executor.0:23887 blocked for more than 140 seconds.
Not tainted 4.14.112+ #57
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0 D30176 23887 1840 0x00000004
Call Trace:
schedule+0x92/0x1c0 kernel/sched/core.c:3498
__rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:572 [inline]
rwsem_down_write_failed+0x3b1/0x760 kernel/locking/rwsem-xadd.c:601
call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:105
__down_write arch/x86/include/asm/rwsem.h:126 [inline]
down_write+0x4f/0x90 kernel/locking/rwsem.c:56
inode_lock include/linux/fs.h:715 [inline]
vfs_setxattr+0x89/0xe0 fs/xattr.c:219
setxattr+0x1bc/0x330 fs/xattr.c:453
path_setxattr+0x138/0x150 fs/xattr.c:472
SYSC_lsetxattr fs/xattr.c:494 [inline]
SyS_lsetxattr+0x33/0x40 fs/xattr.c:490
do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289

Showing all locks held in the system:
1 lock held by khungtaskd/23:
#0: (tasklist_lock){.+.+}, at: [<000000007dbd6acf>]
debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544
2 locks held by getty/1748:
#0: (&tty->ldisc_sem){++++}, at: [<00000000fe2cbad5>]
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284
#1: (&ldata->atomic_read_lock){+.+.}, at: [<000000004d05e1fd>]
n_tty_read+0x1f7/0x1700 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.0/23887:
#0: (sb_writers#4){.+.+}, at: [<00000000acdbf830>] sb_start_write
include/linux/fs.h:1545 [inline]
#0: (sb_writers#4){.+.+}, at: [<00000000acdbf830>]
mnt_want_write+0x3a/0xb0 fs/namespace.c:387
#1: (&sb->s_type->i_mutex_key#9){++++}, at: [<0000000036ad98a4>]
inode_lock include/linux/fs.h:715 [inline]
#1: (&sb->s_type->i_mutex_key#9){++++}, at: [<0000000036ad98a4>]
vfs_setxattr+0x89/0xe0 fs/xattr.c:219

=============================================



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[syzbot]

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