Re: [syzbot] WARNING: suspicious RCU usage in evict

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    521a547ced64 Linux 6.0-rc6
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13cd7937080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=122d7bd4fc8e0ecb
dashboard link: https://syzkaller.appspot.com/bug?extid=45df7ccc8b5bade4f745
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=143df15f080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+45df7ccc8b5bade4f745@xxxxxxxxxxxxxxxxxxxxxxxxx

ntfs3: loop1: RAW NTFS volume: Filesystem size 0.00 Gb > volume size 0.00 Gb. Mount in read-only
=============================
WARNING: suspicious RCU usage
6.0.0-rc6-syzkaller #0 Not tainted
-----------------------------
include/trace/events/lock.h:69 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor.1/3793:
 #0: ffff88806df000e0 (&type->s_umount_key#47/1){+.+.}-{3:3}, at: alloc_super+0x22e/0xb60 fs/super.c:228
 #1: ffff88806df009d8 (&s->s_inode_list_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline]
 #1: ffff88806df009d8 (&s->s_inode_list_lock){+.+.}-{2:2}, at: inode_sb_list_del fs/inode.c:503 [inline]
 #1: ffff88806df009d8 (&s->s_inode_list_lock){+.+.}-{2:2}, at: evict+0x179/0x6b0 fs/inode.c:654

stack backtrace:
CPU: 1 PID: 3793 Comm: syz-executor.1 Not tainted 6.0.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release.cold+0x1f/0x4e kernel/locking/lockdep.c:5677
 __raw_spin_unlock include/linux/spinlock_api_smp.h:141 [inline]
 _raw_spin_unlock+0x12/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:389 [inline]
 inode_sb_list_del fs/inode.c:505 [inline]
 evict+0x2aa/0x6b0 fs/inode.c:654
 iput_final fs/inode.c:1748 [inline]
 iput.part.0+0x55d/0x810 fs/inode.c:1774
 iput+0x58/0x70 fs/inode.c:1764
 ntfs_fill_super+0x2309/0x37f0 fs/ntfs3/super.c:1278
 get_tree_bdev+0x440/0x760 fs/super.c:1323
 vfs_get_tree+0x89/0x2f0 fs/super.c:1530
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 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]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 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: 0033:0x7f67e5a8a93a
Code: 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 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:00007f67e6cb5f88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f67e5a8a93a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f67e6cb5fe0
RBP: 00007f67e6cb6020 R08: 00007f67e6cb6020 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 00007f67e6cb5fe0 R15: 0000000020003580
 </TASK>