[syzbot] [integrity?] [lsm?] WARNING: bad unlock balance in __filemap_add_folio

[syzbot <syzbot+914bc925a90b7e137017@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    2e6803928193 Merge tag 'tracefs-v7.1-2' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=117dff16580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=80b28e8d6ef9384a
dashboard link: https://syzkaller.appspot.com/bug?extid=914bc925a90b7e137017
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/690094a31275/disk-2e680392.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7d17ea4e1f81/vmlinux-2e680392.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c1478f49f523/bzImage-2e680392.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+914bc925a90b7e137017@syzkaller.appspotmail.com

cgroup: Unknown subsys name 'cpuset'
cgroup: Unknown subsys name 'rlimit'
=====================================
WARNING: bad unlock balance detected!
syzkaller #0 Not tainted
-------------------------------------
syz-executor/5795 is trying to release lock (rcu_read_lock) at:
[<ffffffff8b2f32cf>] rcu_lock_release include/linux/rcupdate.h:310 [inline]
[<ffffffff8b2f32cf>] rcu_read_unlock include/linux/rcupdate.h:869 [inline]
[<ffffffff8b2f32cf>] rt_spin_unlock+0x14f/0x200 kernel/locking/spinlock_rt.c:82
but there are no more locks to release!

other info that might help us debug this:
2 locks held by syz-executor/5795:
 #0: ffff888035e50f58 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: process_measurement+0x7fd/0x1c90 security/integrity/ima/ima_main.c:319
 #1: ffff8880434dc100 (mapping.invalidate_lock#2){++++}-{4:4}, at: filemap_invalidate_lock_shared include/linux/fs.h:1094 [inline]
 #1: ffff8880434dc100 (mapping.invalidate_lock#2){++++}-{4:4}, at: do_page_cache_ra mm/readahead.c:333 [inline]
 #1: ffff8880434dc100 (mapping.invalidate_lock#2){++++}-{4:4}, at: page_cache_ra_order+0x2a5/0x490 mm/readahead.c:538

stack backtrace:
CPU: 1 UID: 0 PID: 5795 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0xdc/0xf0 kernel/locking/lockdep.c:5298
 __lock_release kernel/locking/lockdep.c:5537 [inline]
 lock_release+0x248/0x3c0 kernel/locking/lockdep.c:5889
 rcu_lock_release include/linux/rcupdate.h:310 [inline]
 rcu_read_unlock include/linux/rcupdate.h:869 [inline]
 rt_spin_unlock+0x15b/0x200 kernel/locking/spinlock_rt.c:82
 spin_unlock_irq include/linux/spinlock_rt.h:122 [inline]
 __filemap_add_folio+0xc85/0x1200 mm/filemap.c:931
 filemap_add_folio+0x2de/0x610 mm/filemap.c:967
 page_cache_ra_unbounded+0x407/0x980 mm/readahead.c:282
 do_page_cache_ra mm/readahead.c:334 [inline]
 page_cache_ra_order+0x2b5/0x490 mm/readahead.c:538
 filemap_readahead mm/filemap.c:2664 [inline]
 filemap_get_pages+0x832/0x1e70 mm/filemap.c:2710
 filemap_read+0x44a/0x1240 mm/filemap.c:2806
 __kernel_read+0x50d/0x9c0 fs/read_write.c:532
 integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
 ima_calc_file_hash+0x452/0x870 security/integrity/ima/ima_crypto.c:280
 ima_collect_measurement+0x523/0x9d0 security/integrity/ima/ima_api.c:300
 process_measurement+0x12d9/0x1c90 security/integrity/ima/ima_main.c:425
 ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
 security_file_post_open+0xb3/0x260 security/security.c:2755
 do_open fs/namei.c:4701 [inline]
 path_openat+0x2e88/0x38a0 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 file_open_name+0x162/0x1c0 fs/open.c:1322
 __do_sys_swapon mm/swapfile.c:3467 [inline]
 __se_sys_swapon+0x856/0x2010 mm/swapfile.c:3432
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f884264c7d7
Code: 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a7 00 00 00 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:00007ffe6306a658 EFLAGS: 00000246 ORIG_RAX: 00000000000000a7
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f884264c7d7
RDX: 0000000000000000 RSI: 0000000000008000 RDI: 00007f88426e2e5b
RBP: 00007f88426e2e5b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 00007f88428963e0
R13: 00007f88426fdd26 R14: 0000000000200000 R15: 00007f88428963a0
 </TASK>
------------[ cut here ]------------
rrln < 0 || rrln > RCU_NEST_PMAX
WARNING: kernel/rcu/tree_plugin.h:443 at __rcu_read_unlock+0x79/0xe0 kernel/rcu/tree_plugin.h:443, CPU#1: syz-executor/5795
Modules linked in:
CPU: 1 UID: 0 PID: 5795 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__rcu_read_unlock+0x79/0xe0 kernel/rcu/tree_plugin.h:443
Code: 75 66 41 83 3e 00 75 27 43 0f b6 04 3c 84 c0 75 41 8b 03 3d 00 00 00 40 73 0f 5b 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc cc 90 <0f> 0b 90 eb eb e8 6d 00 00 00 eb d2 89 d9 80 e1 07 80 c1 03 38 c1
RSP: 0018:ffffc900046e6418 EFLAGS: 00010286
RAX: 00000000ffffffff RBX: ffff888039e82384 RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8d8986dc RDI: ffff888039e81ec0
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1bcaacc R12: 1ffff110073d0470
R13: ffff888039e81ec0 R14: ffff8880b893c610 R15: dffffc0000000000
FS:  000055555b61b540(0000) GS:ffff8881261fb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec05db0e9c CR3: 0000000042cbe000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_unlock include/linux/rcupdate.h:871 [inline]
 rt_spin_unlock+0x160/0x200 kernel/locking/spinlock_rt.c:82
 spin_unlock_irq include/linux/spinlock_rt.h:122 [inline]
 __filemap_add_folio+0xc85/0x1200 mm/filemap.c:931
 filemap_add_folio+0x2de/0x610 mm/filemap.c:967
 page_cache_ra_unbounded+0x407/0x980 mm/readahead.c:282
 do_page_cache_ra mm/readahead.c:334 [inline]
 page_cache_ra_order+0x2b5/0x490 mm/readahead.c:538
 filemap_readahead mm/filemap.c:2664 [inline]
 filemap_get_pages+0x832/0x1e70 mm/filemap.c:2710
 filemap_read+0x44a/0x1240 mm/filemap.c:2806
 __kernel_read+0x50d/0x9c0 fs/read_write.c:532
 integrity_kernel_read+0x89/0xd0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:222 [inline]
 ima_calc_file_hash+0x452/0x870 security/integrity/ima/ima_crypto.c:280
 ima_collect_measurement+0x523/0x9d0 security/integrity/ima/ima_api.c:300
 process_measurement+0x12d9/0x1c90 security/integrity/ima/ima_main.c:425
 ima_file_check+0xe1/0x130 security/integrity/ima/ima_main.c:685
 security_file_post_open+0xb3/0x260 security/security.c:2755
 do_open fs/namei.c:4701 [inline]
 path_openat+0x2e88/0x38a0 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 file_open_name+0x162/0x1c0 fs/open.c:1322
 __do_sys_swapon mm/swapfile.c:3467 [inline]
 __se_sys_swapon+0x856/0x2010 mm/swapfile.c:3432
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f884264c7d7
Code: 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a7 00 00 00 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:00007ffe6306a658 EFLAGS: 00000246 ORIG_RAX: 00000000000000a7
RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f884264c7d7
RDX: 0000000000000000 RSI: 0000000000008000 RDI: 00007f88426e2e5b
RBP: 00007f88426e2e5b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 00007f88428963e0
R13: 00007f88426fdd26 R14: 0000000000200000 R15: 00007f88428963a0
 </TASK>


---
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