[syzbot] WARNING: suspicious RCU usage in write_inode_now (2)

syzbot
2022-12-07T07:00:48Z

Hello,

syzbot found the following issue on:

HEAD commit: a5541c0811a0 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1080851d880000
kernel config: https://syzkaller.appspot.com/x/.config?x=cbd4e584773e9397
dashboard link: https://syzkaller.appspot.com/bug?extid=5294a9e355351fddb4b2
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4b7702208fb9/disk-a5541c08.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9ec0153ec051/vmlinux-a5541c08.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f8725ad290a/Image-a5541c08.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5294a9e355351fddb4b2@syzkaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0 Not tainted
-----------------------------
kernel/sched/core.c:9870 Illegal context switch in RCU-bh read-side critical section!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor.5/19612:
#0: ffff0001428b30e0 (&type->s_umount_key#94/1){+.+.}-{3:3}, at: alloc_super+0xf8/0x430 fs/super.c:228

stack backtrace:
CPU: 0 PID: 19612 Comm: syz-executor.5 Not tainted 6.1.0-rc8-syzkaller-33330-ga5541c0811a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
Call trace:
dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:163
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
lockdep_rcu_suspicious+0x138/0x154 kernel/locking/lockdep.c:6597
__might_resched+0x6c/0x218 kernel/sched/core.c:9870
__might_sleep+0x48/0x78 kernel/sched/core.c:9837
write_inode_now+0xa4/0xdc fs/fs-writeback.c:2743
iput_final fs/inode.c:1734 [inline]
iput+0x1e4/0x324 fs/inode.c:1773
ntfs_fill_super+0x1254/0x14a4 fs/ntfs3/super.c:1190
get_tree_bdev+0x1e8/0x2a0 fs/super.c:1324
ntfs_fs_get_tree+0x28/0x38 fs/ntfs3/super.c:1358
vfs_get_tree+0x40/0x140 fs/super.c:1531
do_new_mount+0x1dc/0x4e4 fs/namespace.c:3040
path_mount+0x358/0x890 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__arm64_sys_mount+0x2c4/0x3c4 fs/namespace.c:3568
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x140 arch/arm64/kernel/syscall.c:197
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:584

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