[syzbot] [f2fs?] WARNING: suspicious RCU usage in __f2fs_add_ino_entry

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4477a78374a5 Add linux-next specific files for 20260814
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=150bea25580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b32a36dd637b06f
dashboard link: https://syzkaller.appspot.com/bug?extid=014a7b70788139e6196d
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d3fa79580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/994c1c8c560e/disk-4477a783.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cd54543d69ae/vmlinux-4477a783.xz
kernel image: https://storage.googleapis.com/syzbot-assets/407cdf8f3fc2/bzImage-4477a783.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/12687adce9ef/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=171cd949580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+014a7b...@syzkaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
./include/linux/radix-tree.h:179 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
locks held by kworker/u9:3/5775: 4, last CPU#0:
#0: ffff88807f597940 ((wq_completion)f2fs_evict_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88807f597940 ((wq_completion)f2fs_evict_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88807f597940 ((wq_completion)f2fs_evict_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
#0: ffff88807f597940 ((wq_completion)f2fs_evict_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
#1: ffffc90003fb7c40 ((work_completion)(&ew->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90003fb7c40 ((work_completion)(&ew->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90003fb7c40 ((work_completion)(&ew->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3352 [inline]
#1: ffffc90003fb7c40 ((work_completion)(&ew->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3470
#2: ffff8880b863a820 (lock){+.+.}-{3:3}, at: local_lock_acquire include/linux/local_lock_internal.h:46 [inline]
#2: ffff8880b863a820 (lock){+.+.}-{3:3}, at: __radix_tree_preload+0x82/0x870 lib/radix-tree.c:334
#3: ffff8880338688c8 (&im->ino_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:347 [inline]
#3: ffff8880338688c8 (&im->ino_lock){+.+.}-{3:3}, at: __set_ino_bitmap fs/f2fs/checkpoint.c:781 [inline]
#3: ffff8880338688c8 (&im->ino_lock){+.+.}-{3:3}, at: __f2fs_add_ino_entry+0x14c/0x830 fs/f2fs/checkpoint.c:842

stack backtrace:
CPU: 0 UID: 0 PID: 5775 Comm: kworker/u9:3 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: f2fs_evict_wq f2fs_evict_inode_work
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
lockdep_rcu_suspicious+0x140/0x1d0 kernel/locking/lockdep.c:6938
radix_tree_deref_slot include/linux/radix-tree.h:179 [inline]
__set_ino_bitmap fs/f2fs/checkpoint.c:784 [inline]
__f2fs_add_ino_entry+0x782/0x830 fs/f2fs/checkpoint.c:842
f2fs_record_inode_state fs/f2fs/inode.c:877 [inline]
f2fs_evict_inode_work+0xa1/0x120 fs/f2fs/inode.c:887
process_one_work kernel/workqueue.c:3387 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


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