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 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the bug is already fixed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to change bug's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the bug is a duplicate of another bug, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
