syzbot

efivarfs: resyncing variable state
============================================
WARNING: possible recursive locking detected
6.14.0-rc7-syzkaller-ga2392f333575 #0 Not tainted
--------------------------------------------
syz-executor372/6438 is trying to acquire lock:
ffff0000c6c8e558 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
ffff0000c6c8e558 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: efivarfs_actor+0x1b8/0x2b8 fs/efivarfs/super.c:424

but task is already holding lock:
ffff0000c70c6558 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: iterate_dir+0x3b4/0x5f4 fs/readdir.c:101

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sb->s_type->i_mutex_key#16);
  lock(&sb->s_type->i_mutex_key#16);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz-executor372/6438:
 #0: ffff80008fc57588 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x68/0xc0 kernel/power/main.c:56
 #1: ffff80008fc760f0 ((pm_chain_head).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0 kernel/notifier.c:379
 #2: ffff0000c70c6558 (&sb->s_type->i_mutex_key#16){++++}-{4:4}, at: iterate_dir+0x3b4/0x5f4 fs/readdir.c:101

stack backtrace:
CPU: 0 UID: 0 PID: 6438 Comm: syz-executor372 Not tainted 6.14.0-rc7-syzkaller-ga2392f333575 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_deadlock_bug+0x4e8/0x668 kernel/locking/lockdep.c:3039
 check_deadlock kernel/locking/lockdep.c:3091 [inline]
 validate_chain kernel/locking/lockdep.c:3893 [inline]
 __lock_acquire+0x6240/0x7904 kernel/locking/lockdep.c:5228
 lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5851
 down_write+0x50/0xc0 kernel/locking/rwsem.c:1577
 inode_lock include/linux/fs.h:877 [inline]
 efivarfs_actor+0x1b8/0x2b8 fs/efivarfs/super.c:424
 dir_emit include/linux/fs.h:3851 [inline]
 dcache_readdir+0x2dc/0x4e8 fs/libfs.c:209
 iterate_dir+0x46c/0x5f4 fs/readdir.c:108
 efivarfs_pm_notify+0x2f4/0x350 fs/efivarfs/super.c:519
 notifier_call_chain+0x1c4/0x550 kernel/notifier.c:85
 blocking_notifier_call_chain+0x70/0xa0 kernel/notifier.c:380
 pm_notifier_call_chain+0x2c/0x3c kernel/power/main.c:109
 snapshot_release+0x128/0x1b8 kernel/power/user.c:125
 __fput+0x340/0x760 fs/file_table.c:464
 ____fput+0x20/0x30 fs/file_table.c:492
 task_work_run+0x230/0x2e0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 do_notify_resume+0x178/0x1f4 arch/arm64/kernel/entry-common.c:151
 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
 el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:745
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600