[syzbot] [kernel?] possible deadlock in assign_fw

[syzbot <syzbot+e70e4c6f6eee43357ba7@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    e9d22f7a6655 Merge tag 'linux_kselftest-fixes-6.10-rc7' of..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1471b399980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=864caee5f78cab51
dashboard link: https://syzkaller.appspot.com/bug?extid=e70e4c6f6eee43357ba7
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c3dd72a93425/disk-e9d22f7a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9d79986da9dc/vmlinux-e9d22f7a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0df271bec574/bzImage-e9d22f7a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e70e4c6f6eee43357ba7@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 000000000000006e R14: 00007f30c0504038 R15: 00007f30c062fa68
 </TASK>
============================================
WARNING: possible recursive locking detected
6.10.0-rc6-syzkaller-00061-ge9d22f7a6655 #0 Not tainted
--------------------------------------------
syz.1.2110/15436 is trying to acquire lock:
ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: assign_fw+0x56/0x890 drivers/base/firmware_loader/main.c:700

but task is already holding lock:
ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: device_cache_fw_images drivers/base/firmware_loader/main.c:1483 [inline]
ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: fw_pm_notify+0x232/0x2f0 drivers/base/firmware_loader/main.c:1536

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

       CPU0
       ----
  lock(fw_lock);
  lock(fw_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz.1.2110/15436:
 #0: ffffffff8eb2f6e8 (misc_mtx){+.+.}-{3:3}, at: misc_open+0x5c/0x390 drivers/char/misc.c:129
 #1: ffffffff8e1e7368 (system_transition_mutex){+.+.}-{3:3}, at: lock_system_sleep+0x60/0xa0 kernel/power/main.c:56
 #2: ffffffff8e2077f0 ((pm_chain_head).rwsem){++++}-{3:3}, at: blocking_notifier_call_chain_robust+0xac/0x1e0 kernel/notifier.c:352
 #3: ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: device_cache_fw_images drivers/base/firmware_loader/main.c:1483 [inline]
 #3: ffffffff8ec73968 (fw_lock){+.+.}-{3:3}, at: fw_pm_notify+0x232/0x2f0 drivers/base/firmware_loader/main.c:1536
 #4: ffffffff8ec6ea08 (dpm_list_mtx){+.+.}-{3:3}, at: device_pm_lock drivers/base/power/main.c:113 [inline]
 #4: ffffffff8ec6ea08 (dpm_list_mtx){+.+.}-{3:3}, at: dpm_for_each_dev+0x2b/0xc0 drivers/base/power/main.c:1961

stack backtrace:
CPU: 0 PID: 15436 Comm: syz.1.2110 Not tainted 6.10.0-rc6-syzkaller-00061-ge9d22f7a6655 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain+0x15d3/0x5900 kernel/locking/lockdep.c:3856
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 assign_fw+0x56/0x890 drivers/base/firmware_loader/main.c:700
 _request_firmware+0xd0a/0x12b0 drivers/base/firmware_loader/main.c:917
 request_firmware drivers/base/firmware_loader/main.c:963 [inline]
 cache_firmware drivers/base/firmware_loader/main.c:1265 [inline]
 __async_dev_cache_fw_image+0xe7/0x320 drivers/base/firmware_loader/main.c:1379
 async_schedule_node_domain+0xdc/0x110 kernel/async.c:221
 async_schedule_domain include/linux/async.h:72 [inline]
 dev_cache_fw_image+0x36d/0x3e0 drivers/base/firmware_loader/main.c:1435
 dpm_for_each_dev+0x58/0xc0 drivers/base/power/main.c:1963
 device_cache_fw_images drivers/base/firmware_loader/main.c:1485 [inline]
 fw_pm_notify+0x24a/0x2f0 drivers/base/firmware_loader/main.c:1536
 notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
 notifier_call_chain_robust kernel/notifier.c:128 [inline]
 blocking_notifier_call_chain_robust+0xe8/0x1e0 kernel/notifier.c:353
 pm_notifier_call_chain_robust+0x2c/0x60 kernel/power/main.c:102
 snapshot_open+0x1a1/0x280 kernel/power/user.c:77
 misc_open+0x313/0x390 drivers/char/misc.c:165
 chrdev_open+0x5b0/0x630 fs/char_dev.c:414
 do_dentry_open+0x970/0x1450 fs/open.c:955
 vfs_open+0x3e/0x330 fs/open.c:1086
 do_open fs/namei.c:3654 [inline]
 path_openat+0x2c01/0x35f0 fs/namei.c:3813
 do_filp_open+0x235/0x490 fs/namei.c:3840
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1413
 do_sys_open fs/open.c:1428 [inline]
 __do_sys_openat fs/open.c:1444 [inline]
 __se_sys_openat fs/open.c:1439 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1439
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f30c0375bd9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f30c1120048 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f30c0504038 RCX: 00007f30c0375bd9
RDX: 0000000000000000 RSI: 0000000020000080 RDI: ffffffffffffff9c
RBP: 00007f30c11200a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 000000000000006e R14: 00007f30c0504038 R15: 00007f30c062fa68
 </TASK>


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