[syzbot] [cgroups?] possible deadlock in freezer_css_online

From: syzbot
Date: Sat Jun 10 2023 - 07:08:09 EST

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Hello,

syzbot found the following issue on:

HEAD commit: f8dba31b0a82 Merge tag 'asym-keys-fix-for-linus-v6.4-rc5' ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12464b7d280000
kernel config: https://syzkaller.appspot.com/x/.config?x=befacc9fbc9cd0ac
dashboard link: https://syzkaller.appspot.com/bug?extid=387de8f7ae917a47dc5e
compiler: aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/384ffdcca292/non_bootable_disk-f8dba31b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7059eda5ac77/vmlinux-f8dba31b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/25f8cdcaad99/Image-f8dba31b.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+387de8f7ae917a47dc5e@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc5-syzkaller-00002-gf8dba31b0a82 #0 Not tainted
------------------------------------------------------
syz-executor.1/11374 is trying to acquire lock:
ffff80000e31c1b0 (cpu_hotplug_lock){++++}-{0:0}, at: cpus_read_lock+0x10/0x1c kernel/cpu.c:310

but task is already holding lock:
ffff80000e4c0da8 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4c/0x178 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}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x124/0x830 kernel/locking/mutex.c:747
mutex_lock_nested+0x24/0x30 kernel/locking/mutex.c:799
freezer_change_state kernel/cgroup/legacy_freezer.c:389 [inline]
freezer_write+0x84/0x640 kernel/cgroup/legacy_freezer.c:429
cgroup_file_write+0x218/0x5b4 kernel/cgroup/cgroup.c:4071
kernfs_fop_write_iter+0x264/0x3c4 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+0x4cc/0x748 fs/read_write.c:584
ksys_write+0xec/0x1d0 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x6c/0x9c fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x50/0x124 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x130 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0xb8/0xbc arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

-> #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 kernel/locking/lockdep.c:3847 [inline]
__lock_acquire+0x27c4/0x5270 kernel/locking/lockdep.c:5088
lock_acquire kernel/locking/lockdep.c:5705 [inline]
lock_acquire+0x478/0x7c0 kernel/locking/lockdep.c:5670
percpu_down_read.constprop.0+0x58/0x1f0 include/linux/percpu-rwsem.h:51
cpus_read_lock+0x10/0x1c kernel/cpu.c:310
static_key_slow_inc+0x18/0x50 kernel/jump_label.c:185
freezer_css_online+0xe4/0x178 kernel/cgroup/legacy_freezer.c:117
online_css+0x90/0x260 kernel/cgroup/cgroup.c:5491
css_create kernel/cgroup/cgroup.c:5562 [inline]
cgroup_apply_control_enable+0x48c/0x960 kernel/cgroup/cgroup.c:3249
cgroup_mkdir+0x4b0/0xdf0 kernel/cgroup/cgroup.c:5758
kernfs_iop_mkdir+0x104/0x184 fs/kernfs/dir.c:1219
vfs_mkdir+0x1a8/0x370 fs/namei.c:4115
do_mkdirat+0x20c/0x24c fs/namei.c:4138
__do_sys_mkdirat fs/namei.c:4153 [inline]
__se_sys_mkdirat fs/namei.c:4151 [inline]
__arm64_sys_mkdirat+0xdc/0x138 fs/namei.c:4151
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x50/0x124 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x130 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0xb8/0xbc arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

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-executor.1/11374:
#0: ffff0000143f8460 (sb_writers#10){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1494 [inline]
#0: ffff0000143f8460 (sb_writers#10){.+.+}-{0:0}, at: sb_start_write include/linux/fs.h:1569 [inline]
#0: ffff0000143f8460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3c/0xb0 fs/namespace.c:394
#1: ffff00000f0733f0 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:810 [inline]
#1: ffff00000f0733f0 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: filename_create+0x150/0x348 fs/namei.c:3884
#2: ffff80000e4b0fa8 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock include/linux/cgroup.h:370 [inline]
#2: ffff80000e4b0fa8 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xe0/0x578 kernel/cgroup/cgroup.c:1683
#3: ffff80000e4c0da8 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4c/0x178 kernel/cgroup/legacy_freezer.c:111

stack backtrace:
CPU: 0 PID: 11374 Comm: syz-executor.1 Not tainted 6.4.0-rc5-syzkaller-00002-gf8dba31b0a82 #0
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x9c/0x11c arch/arm64/kernel/stacktrace.c:233
show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x74/0xd4 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
print_circular_bug+0x400/0x704 kernel/locking/lockdep.c:2066
check_noncircular+0x26c/0x2e0 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 kernel/locking/lockdep.c:3847 [inline]
__lock_acquire+0x27c4/0x5270 kernel/locking/lockdep.c:5088
lock_acquire kernel/locking/lockdep.c:5705 [inline]
lock_acquire+0x478/0x7c0 kernel/locking/lockdep.c:5670
percpu_down_read.constprop.0+0x58/0x1f0 include/linux/percpu-rwsem.h:51
cpus_read_lock+0x10/0x1c kernel/cpu.c:310
static_key_slow_inc+0x18/0x50 kernel/jump_label.c:185
freezer_css_online+0xe4/0x178 kernel/cgroup/legacy_freezer.c:117
online_css+0x90/0x260 kernel/cgroup/cgroup.c:5491
css_create kernel/cgroup/cgroup.c:5562 [inline]
cgroup_apply_control_enable+0x48c/0x960 kernel/cgroup/cgroup.c:3249
cgroup_mkdir+0x4b0/0xdf0 kernel/cgroup/cgroup.c:5758
kernfs_iop_mkdir+0x104/0x184 fs/kernfs/dir.c:1219
vfs_mkdir+0x1a8/0x370 fs/namei.c:4115
do_mkdirat+0x20c/0x24c fs/namei.c:4138
__do_sys_mkdirat fs/namei.c:4153 [inline]
__se_sys_mkdirat fs/namei.c:4151 [inline]
__arm64_sys_mkdirat+0xdc/0x138 fs/namei.c:4151
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x50/0x124 arch/arm64/kernel/syscall.c:193
el0_svc+0x4c/0x130 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0xb8/0xbc arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

---
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Next message: Alan Huang: "Re: [PATCH 4/4] Docs/RCU/rculist_nulls: Drop unnecessary '_release' in insert function"
Previous message: Arınç ÜNAL: "Re: [PATCH net-next 08/30] net: dsa: mt7530: change p{5,6}_interface to p{5,6}_configured"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]