=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
fs/btrfs/volumes.h:872 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
6 locks held by syz.4.353/7093:
 #0: ffff888025eee9b8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1261
 #1: ffff888078edc420 (sb_writers#23){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2710 [inline]
 #1: ffff888078edc420 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x227/0xb90 fs/read_write.c:684
 #2: ffff888078edc610 (sb_internal#4){.+.+}-{0:0}, at: btrfs_sync_file+0xcaa/0x1230 fs/btrfs/file.c:1724
 #3: ffff8880586367c0 (btrfs_trans_completed){.+.+}-{0:0}, at: btrfs_commit_transaction+0x1a2/0x2fc0 fs/btrfs/transaction.c:2212
 #4: ffff888058636798 (btrfs_trans_super_committed){.+.+}-{0:0}, at: btrfs_commit_transaction+0x1a2/0x2fc0 fs/btrfs/transaction.c:2212
 #5: ffff888058634838 (&fs_info->tree_log_mutex){+.+.}-{4:4}, at: btrfs_commit_transaction+0x1c48/0x2fc0 fs/btrfs/transaction.c:2534

stack backtrace:
CPU: 0 UID: 0 PID: 7093 Comm: syz.4.353 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 lockdep_rcu_suspicious+0x13f/0x1d0 kernel/locking/lockdep.c:6876
 btrfs_dev_name fs/btrfs/volumes.h:872 [inline]
 btrfs_dev_stat_inc_and_print+0x328/0x400 fs/btrfs/volumes.c:8282
 btrfs_log_dev_io_error fs/btrfs/bio.c:-1 [inline]
 btrfs_simple_end_io+0x1e6/0x3e0 fs/btrfs/bio.c:399
 btrfs_submit_chunk fs/btrfs/bio.c:848 [inline]
 btrfs_submit_bbio+0x1316/0x1ea0 fs/btrfs/bio.c:906
 btree_writepages+0xb68/0x1260 fs/btrfs/extent_io.c:2390
 do_writepages+0x32e/0x550 mm/page-writeback.c:2554
 filemap_writeback mm/filemap.c:387 [inline]
 filemap_fdatawrite_range+0x1ef/0x2f0 mm/filemap.c:412
 btrfs_write_marked_extents+0x1ac/0x300 fs/btrfs/transaction.c:1174
 btrfs_write_and_wait_transaction fs/btrfs/transaction.c:1282 [inline]
 btrfs_commit_transaction+0x1e01/0x2fc0 fs/btrfs/transaction.c:2550
 btrfs_sync_file+0xdf0/0x1230 fs/btrfs/file.c:1817
 generic_write_sync include/linux/fs.h:2640 [inline]
 btrfs_do_write_iter+0x72e/0x880 fs/btrfs/file.c:1468
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:688
 ksys_write+0x150/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbc6f79c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc7060f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fbc6fa16090 RCX: 00007fbc6f79c799
RDX: 0000000000000020 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007fbc6f832bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc6fa16128 R14: 00007fbc6fa16090 R15: 00007ffd7e74c958
 </TASK>
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 1, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 2, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 3, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 4, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 5, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 6, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): bdev /dev/loop4 errs: wr 7, rd 0, flush 0, corrupt 0, gen 0
BTRFS error (device loop4): error while writing out transaction: -5
BTRFS warning (device loop4): Skipping commit of aborted transaction.
BTRFS error (device loop4 state A): Transaction aborted (error -5)
BTRFS: error (device loop4 state A) in cleanup_transaction:2042: errno=-5 IO failure
BTRFS info (device loop4 state EA): forced readonly