[syzbot] [cgroups?] possible deadlock in static_key_slow_inc (3)

* [syzbot] [cgroups?] possible deadlock in static_key_slow_inc (3)
@ 2023-06-08 16:56 ` syzbot
  0 siblings, 0 replies; 6+ messages in thread
From: syzbot @ 2023-06-08 16:56 UTC (permalink / raw)
  To: cgroups, hannes, linux-kernel, lizefan.x, syzkaller-bugs, tj

Hello,

syzbot found the following issue on:

HEAD commit:    5f63595ebd82 Merge tag 'input-for-v6.4-rc5' of git://git.k..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=153fcc63280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7474de833c217bf4
dashboard link: https://syzkaller.appspot.com/bug?extid=2ab700fe1829880a2ec6
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1321e2fd280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11946afd280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d12b9e46ffe8/disk-5f63595e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c9044ded7edd/vmlinux-5f63595e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/09f0fd3926e8/bzImage-5f63595e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ab700fe1829880a2ec6@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc5-syzkaller-00024-g5f63595ebd82 #0 Not tainted
------------------------------------------------------
syz-executor324/4995 is trying to acquire lock:
ffffffff8cdc3ff0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0x12/0x30 kernel/jump_label.c:185

but task is already holding lock:
ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4f/0x150 kernel/cgroup/legacy_freezer.c:111

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (freezer_mutex){+.+.}-{3:3}:
       lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5705
       __mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799
       freezer_change_state kernel/cgroup/legacy_freezer.c:389 [inline]
       freezer_write+0xa8/0x3f0 kernel/cgroup/legacy_freezer.c:429
       cgroup_file_write+0x2ca/0x6a0 kernel/cgroup/cgroup.c:4071
       kernfs_fop_write_iter+0x3a6/0x4f0 fs/kernfs/file.c:334
       call_write_iter include/linux/fs.h:1868 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x790/0xb20 fs/read_write.c:584
       ksys_write+0x1a0/0x2c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (cpu_hotplug_lock){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3113 [inline]
       check_prevs_add kernel/locking/lockdep.c:3232 [inline]
       validate_chain+0x166b/0x58f0 kernel/locking/lockdep.c:3847
       __lock_acquire+0x1316/0x2070 kernel/locking/lockdep.c:5088
       lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5705
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       cpus_read_lock+0x42/0x150 kernel/cpu.c:310
       static_key_slow_inc+0x12/0x30 kernel/jump_label.c:185
       freezer_css_online+0xc6/0x150 kernel/cgroup/legacy_freezer.c:117
       online_css+0xba/0x260 kernel/cgroup/cgroup.c:5491
       css_create kernel/cgroup/cgroup.c:5562 [inline]
       cgroup_apply_control_enable+0x7d1/0xae0 kernel/cgroup/cgroup.c:3249
       cgroup_mkdir+0xd8f/0x1000 kernel/cgroup/cgroup.c:5758
       kernfs_iop_mkdir+0x279/0x400 fs/kernfs/dir.c:1219
       vfs_mkdir+0x29d/0x450 fs/namei.c:4115
       do_mkdirat+0x264/0x520 fs/namei.c:4138
       __do_sys_mkdirat fs/namei.c:4153 [inline]
       __se_sys_mkdirat fs/namei.c:4151 [inline]
       __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(freezer_mutex);
                               lock(cpu_hotplug_lock);
                               lock(freezer_mutex);
  rlock(cpu_hotplug_lock);

 *** DEADLOCK ***

4 locks held by syz-executor324/4995:
 #0: ffff88807da6c460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:394
 #1: ffff888075c6eee0 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:810 [inline]
 #1: ffff888075c6eee0 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: filename_create+0x260/0x530 fs/namei.c:3884
 #2: ffffffff8cf4f768 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock include/linux/cgroup.h:370 [inline]
 #2: ffffffff8cf4f768 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xe9/0x290 kernel/cgroup/cgroup.c:1683
 #3: ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4f/0x150 kernel/cgroup/legacy_freezer.c:111

stack backtrace:
CPU: 0 PID: 4995 Comm: syz-executor324 Not tainted 6.4.0-rc5-syzkaller-00024-g5f63595ebd82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2fe/0x3b0 kernel/locking/lockdep.c:2188
 check_prev_add kernel/locking/lockdep.c:3113 [inline]
 check_prevs_add kernel/locking/lockdep.c:3232 [inline]
 validate_chain+0x166b/0x58f0 kernel/locking/lockdep.c:3847
 __lock_acquire+0x1316/0x2070 kernel/locking/lockdep.c:5088
 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5705
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 cpus_read_lock+0x42/0x150 kernel/cpu.c:310
 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:185
 freezer_css_online+0xc6/0x150 kernel/cgroup/legacy_freezer.c:117
 online_css+0xba/0x260 kernel/cgroup/cgroup.c:5491
 css_create kernel/cgroup/cgroup.c:5562 [inline]
 cgroup_apply_control_enable+0x7d1/0xae0 kernel/cgroup/cgroup.c:3249
 cgroup_mkdir+0xd8f/0x1000 kernel/cgroup/cgroup.c:5758
 kernfs_iop_mkdir+0x279/0x400 fs/kernfs/dir.c:1219
 vfs_mkdir+0x29d/0x450 fs/namei.c:4115
 do_mkdirat+0x264/0x520 fs/namei.c:4138
 __do_sys_mkdirat fs/namei.c:4153 [inline]
 __se_sys_mkdirat fs/namei.c:4151 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7e55624e09
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 15 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff7236ac98 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f7e55624e09
RDX: 00000000000001ff RSI: 0000000020000180 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fff7236acc0 R09: 00007fff7236acc0
R10: 00007fff7236acc0 R11: 0000000000000246 R12: 00007fff7236acbc
R13: 00007fff7236acd0 R14: 00007fff7236ad10 R15: 0000000000000000
 </TASK>

---
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