Re: [syzbot] WARNING: suspicious RCU usage in __ext4_handle_dirty_metadata

[Matthew Wilcox <willy@infradead.org>]

#syz dup: WARNING: suspicious RCU usage in get_timespec64

On Sun, Apr 04, 2021 at 01:55:17PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    5e46d1b7 reiserfs: update reiserfs_xattrs_initialized() co..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10808831d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=78ef1d159159890
> dashboard link: https://syzkaller.appspot.com/bug?extid=cb293a00f01b422bac7d
> 
> 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+cb293a00f01b422bac7d@syzkaller.appspotmail.com
> 
> =============================
> WARNING: suspicious RCU usage
> 5.12.0-rc5-syzkaller #0 Not tainted
> -----------------------------
> kernel/sched/core.c:8294 Illegal context switch in RCU-bh read-side critical section!
> 
> other info that might help us debug this:
> 
> 
> rcu_scheduler_active = 2, debug_locks = 0
> 7 locks held by syz-executor.2/17885:
>  #0: 
> ffff888014000930
>  (
> &f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:961
>  #1: ffff88802455a460 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x12d/0x250 fs/read_write.c:658
>  #2: ffff888080e91888 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:775 [inline]
>  #2: ffff888080e91888 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: ext4_dio_write_iter fs/ext4/file.c:493 [inline]
>  #2: ffff888080e91888 (&sb->s_type->i_mutex_key#9){+.+.}-{3:3}, at: ext4_file_write_iter+0xaeb/0x14e0 fs/ext4/file.c:661
>  #3: ffff888080e91678 (&ei->i_data_sem){++++}-{3:3}, at: ext4_map_blocks+0x5e1/0x17d0 fs/ext4/inode.c:631
>  #4: ffffffff8bf718a0 (rcu_read_lock){....}-{1:2}, at: ieee80211_rx_napi+0x0/0x3d0 arch/x86/include/asm/bitops.h:207
>  #5: ffff88807b381580 (&local->rx_path_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline]
>  #5: ffff88807b381580 (&local->rx_path_lock){+.-.}-{2:2}, at: ieee80211_rx_handlers+0xd7/0xae60 net/mac80211/rx.c:3758
>  #6: ffff8880b9d26358 (hrtimer_bases.lock){-.-.}-{2:2}, at: __run_hrtimer kernel/time/hrtimer.c:1541 [inline]
>  #6: ffff8880b9d26358 (hrtimer_bases.lock){-.-.}-{2:2}, at: __hrtimer_run_queues+0x243/0xe40 kernel/time/hrtimer.c:1601
> 
> stack backtrace:
> CPU: 1 PID: 17885 Comm: syz-executor.2 Not tainted 5.12.0-rc5-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:79 [inline]
>  dump_stack+0x141/0x1d7 lib/dump_stack.c:120
>  ___might_sleep+0x229/0x2c0 kernel/sched/core.c:8294
>  __ext4_handle_dirty_metadata+0x37/0x730 fs/ext4/ext4_jbd2.c:326
>  ext4_mb_mark_diskspace_used+0x991/0x1160 fs/ext4/mballoc.c:3279
>  ext4_mb_new_blocks+0xd46/0x51a0 fs/ext4/mballoc.c:5000
>  ext4_new_meta_blocks+0x2fe/0x360 fs/ext4/balloc.c:693
>  ext4_alloc_branch fs/ext4/indirect.c:335 [inline]
>  ext4_ind_map_blocks+0xb0d/0x2450 fs/ext4/indirect.c:626
>  ext4_map_blocks+0x9c9/0x17d0 fs/ext4/inode.c:640
>  ext4_iomap_alloc fs/ext4/inode.c:3428 [inline]
>  ext4_iomap_begin+0x463/0x7a0 fs/ext4/inode.c:3478
>  iomap_apply+0x177/0xb50 fs/iomap/apply.c:46
>  __iomap_dio_rw+0x71b/0x1280 fs/iomap/direct-io.c:553
>  iomap_dio_rw+0x30/0x90 fs/iomap/direct-io.c:641
>  ext4_dio_write_iter fs/ext4/file.c:551 [inline]
>  ext4_file_write_iter+0xe18/0x14e0 fs/ext4/file.c:661
>  call_write_iter include/linux/fs.h:1977 [inline]
>  new_sync_write+0x426/0x650 fs/read_write.c:518
>  vfs_write+0x796/0xa30 fs/read_write.c:605
>  ksys_write+0x12d/0x250 fs/read_write.c:658
>  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x466459
> 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fadff8ad188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
> RDX: 0000000000248800 RSI: 0000000020000000 RDI: 0000000000000005
> RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
> R13: 00007ffc9e5e3caf R14: 00007fadff8ad300 R15: 0000000000022000
> 
> 
> ---
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