Tue, 06 Aug 2019 20:18:05 -0700 (PDT) > Hello, > > syzbot found the following crash on: > > HEAD commit: 31cc088a Merge tag 'drm-next-2019-07-19' of git://anongit... > git tree: net-next > console output: https://syzkaller.appspot.com/x/log.txt?x=102db48c600000 > kernel config: https://syzkaller.appspot.com/x/.config?x=4dba67bf8b8c9ad7 > dashboard link: https://syzkaller.appspot.com/bug?extid=370e4739fa489334a4ef > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16dd57dc600000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+370e4739fa489334a4ef@xxxxxxxxxxxxxxxxxxxxxxxxx > > 8021q: adding VLAN 0 to HW filter on device batadv0 > WARNING: CPU: 1 PID: 9095 at mm/page_counter.c:62 page_counter_cancel > mm/page_counter.c:62 [inline] > WARNING: CPU: 1 PID: 9095 at mm/page_counter.c:62 > page_counter_cancel+0x5a/0x70 mm/page_counter.c:55 > Kernel panic - not syncing: panic_on_warn set ... > Shutting down cpus with NMI > Kernel Offset: disabled > > ====================================================== > WARNING: possible circular locking dependency detected > 5.2.0+ #67 Not tainted > ------------------------------------------------------ > syz-executor.2/9306 is trying to acquire lock: > 00000000e4252251 ((console_sem).lock){-.-.}, at: down_trylock+0x13/0x70 > kernel/locking/semaphore.c:135 > > but task is already holding lock: > 000000000fdb8781 (per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu)){-...}, at: > cgroup_rstat_updated+0x115/0x2f0 kernel/cgroup/rstat.c:49 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #3 (per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu)){-...}: > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 > cgroup_rstat_updated+0x115/0x2f0 kernel/cgroup/rstat.c:49 > cgroup_base_stat_cputime_account_end.isra.0+0x1d/0x60 kernel/cgroup/rstat.c:361 > __cgroup_account_cputime+0x9e/0xd0 kernel/cgroup/rstat.c:371 > cgroup_account_cputime include/linux/cgroup.h:782 [inline] > update_curr+0x3c8/0x8d0 kernel/sched/fair.c:862 > dequeue_entity+0x1e/0x1100 kernel/sched/fair.c:4014 > dequeue_task_fair+0x65/0x870 kernel/sched/fair.c:5306 > dequeue_task+0x77/0x2e0 kernel/sched/core.c:1195 > sched_move_task+0x1fb/0x350 kernel/sched/core.c:6847 > cpu_cgroup_attach+0x6d/0xb0 kernel/sched/core.c:6970 > cgroup_migrate_execute+0xc56/0x1350 kernel/cgroup/cgroup.c:2524 > cgroup_migrate+0x14f/0x1f0 kernel/cgroup/cgroup.c:2780 > cgroup_attach_task+0x57f/0x860 kernel/cgroup/cgroup.c:2817 > cgroup_procs_write+0x340/0x400 kernel/cgroup/cgroup.c:4777 > cgroup_file_write+0x241/0x790 kernel/cgroup/cgroup.c:3754 > kernfs_fop_write+0x2b8/0x480 fs/kernfs/file.c:315 > __vfs_write+0x8a/0x110 fs/read_write.c:494 > vfs_write+0x268/0x5d0 fs/read_write.c:558 > ksys_write+0x14f/0x290 fs/read_write.c:611 > __do_sys_write fs/read_write.c:623 [inline] > __se_sys_write fs/read_write.c:620 [inline] > __x64_sys_write+0x73/0xb0 fs/read_write.c:620 > do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #2 (&rq->lock){-.-.}: > __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] > _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 > rq_lock kernel/sched/sched.h:1207 [inline] > task_fork_fair+0x6a/0x520 kernel/sched/fair.c:9940 > sched_fork+0x3af/0x900 kernel/sched/core.c:2783 > copy_process+0x1b04/0x6b00 kernel/fork.c:1987 > _do_fork+0x146/0xfa0 kernel/fork.c:2369 > kernel_thread+0xbb/0xf0 kernel/fork.c:2456 > rest_init+0x28/0x37b init/main.c:417 > arch_call_rest_init+0xe/0x1b > start_kernel+0x912/0x951 init/main.c:785 > x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:472 > x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:453 > secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 > > -> #1 (&p->pi_lock){-.-.}: > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 > try_to_wake_up+0xb0/0x1aa0 kernel/sched/core.c:2432 > wake_up_process+0x10/0x20 kernel/sched/core.c:2548 > __up.isra.0+0x136/0x1a0 kernel/locking/semaphore.c:261 > up+0x9c/0xe0 kernel/locking/semaphore.c:186 > __up_console_sem+0xb7/0x1c0 kernel/printk/printk.c:244 > console_unlock+0x695/0xf10 kernel/printk/printk.c:2481 > vprintk_emit+0x2a0/0x700 kernel/printk/printk.c:1986 > vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 > vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 > printk+0xba/0xed kernel/printk/printk.c:2046 > check_stack_usage kernel/exit.c:765 [inline] > do_exit.cold+0x18b/0x314 kernel/exit.c:927 > do_group_exit+0x135/0x360 kernel/exit.c:981 > __do_sys_exit_group kernel/exit.c:992 [inline] > __se_sys_exit_group kernel/exit.c:990 [inline] > __x64_sys_exit_group+0x44/0x50 kernel/exit.c:990 > do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > -> #0 ((console_sem).lock){-.-.}: > check_prev_add kernel/locking/lockdep.c:2405 [inline] > check_prevs_add kernel/locking/lockdep.c:2507 [inline] > validate_chain kernel/locking/lockdep.c:2897 [inline] > __lock_acquire+0x25a9/0x4c30 kernel/locking/lockdep.c:3880 > lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 > down_trylock+0x13/0x70 kernel/locking/semaphore.c:135 > __down_trylock_console_sem+0xa8/0x210 kernel/printk/printk.c:227 > console_trylock+0x15/0xa0 kernel/printk/printk.c:2297 > console_trylock_spinning kernel/printk/printk.c:1706 [inline] > vprintk_emit+0x283/0x700 kernel/printk/printk.c:1985 > vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 > vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 > printk+0xba/0xed kernel/printk/printk.c:2046 > kasan_die_handler arch/x86/mm/kasan_init_64.c:254 [inline] > kasan_die_handler.cold+0x11/0x23 arch/x86/mm/kasan_init_64.c:249 > notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 > __atomic_notifier_call_chain+0xa6/0x1a0 kernel/notifier.c:185 > atomic_notifier_call_chain kernel/notifier.c:195 [inline] > notify_die+0xfb/0x180 kernel/notifier.c:551 > do_general_protection+0x13d/0x300 arch/x86/kernel/traps.c:558 > general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1181 > cgroup_rstat_updated+0x174/0x2f0 kernel/cgroup/rstat.c:64 > cgroup_base_stat_cputime_account_end.isra.0+0x1d/0x60 kernel/cgroup/rstat.c:361 > __cgroup_account_cputime_field+0xd3/0x130 kernel/cgroup/rstat.c:395 > cgroup_account_cputime_field include/linux/cgroup.h:797 [inline] > task_group_account_field kernel/sched/cputime.c:109 [inline] > account_system_index_time+0x1f7/0x390 kernel/sched/cputime.c:172 > irqtime_account_process_tick.isra.0+0x386/0x490 kernel/sched/cputime.c:389 > account_process_tick+0x27f/0x350 kernel/sched/cputime.c:484 > update_process_times+0x25/0x80 kernel/time/timer.c:1637 > tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167 > tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1296 > __run_hrtimer kernel/time/hrtimer.c:1389 [inline] > __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1451 > hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1068 [inline] > smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1093 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:828 > > other info that might help us debug this: > > Chain exists of: > (console_sem).lock --> &rq->lock --> per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu) > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu)); > lock(&rq->lock); > lock(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu)); > lock((console_sem).lock); > > *** DEADLOCK *** > > 6 locks held by syz-executor.2/9306: > #0: 0000000032d2cedf (&sb->s_type->i_mutex_key#12){+.+.}, at: inode_lock > include/linux/fs.h:778 [inline] > #0: 0000000032d2cedf (&sb->s_type->i_mutex_key#12){+.+.}, at: > __sock_release+0x89/0x280 net/socket.c:589 > #1: 000000002033d24d (sk_lock-AF_INET6){+.+.}, at: lock_sock > include/net/sock.h:1522 [inline] > #1: 000000002033d24d (sk_lock-AF_INET6){+.+.}, at: tcp_close+0x27/0x10e0 > net/ipv4/tcp.c:2329 > #2: 0000000067f2fc6a (rcu_read_lock){....}, at: tcp_bpf_unhash+0x0/0x390 > net/ipv4/tcp_bpf.c:480 > #3: 0000000067f2fc6a (rcu_read_lock){....}, at: arch_atomic64_add > arch/x86/include/asm/atomic64_64.h:46 [inline] > #3: 0000000067f2fc6a (rcu_read_lock){....}, at: atomic64_add > include/asm-generic/atomic-instrumented.h:873 [inline] > #3: 0000000067f2fc6a (rcu_read_lock){....}, at: account_group_system_time > include/linux/sched/cputime.h:154 [inline] > #3: 0000000067f2fc6a (rcu_read_lock){....}, at: > account_system_index_time+0xf7/0x390 kernel/sched/cputime.c:169 > #4: 000000000fdb8781 (per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu)){-...}, at: > cgroup_rstat_updated+0x115/0x2f0 kernel/cgroup/rstat.c:49 > #5: 0000000067f2fc6a (rcu_read_lock){....}, at: > __atomic_notifier_call_chain+0x0/0x1a0 kernel/notifier.c:404 > > stack backtrace: > CPU: 0 PID: 9306 Comm: syz-executor.2 Not tainted 5.2.0+ #67 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > print_circular_bug.cold+0x163/0x172 kernel/locking/lockdep.c:1617 > check_noncircular+0x345/0x3e0 kernel/locking/lockdep.c:1741 > check_prev_add kernel/locking/lockdep.c:2405 [inline] > check_prevs_add kernel/locking/lockdep.c:2507 [inline] > validate_chain kernel/locking/lockdep.c:2897 [inline] > __lock_acquire+0x25a9/0x4c30 kernel/locking/lockdep.c:3880 > lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 > down_trylock+0x13/0x70 kernel/locking/semaphore.c:135 > __down_trylock_console_sem+0xa8/0x210 kernel/printk/printk.c:227 > console_trylock+0x15/0xa0 kernel/printk/printk.c:2297 > console_trylock_spinning kernel/printk/printk.c:1706 [inline] > vprintk_emit+0x283/0x700 kernel/printk/printk.c:1985 > vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 > vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 > printk+0xba/0xed kernel/printk/printk.c:2046 > kasan_die_handler arch/x86/mm/kasan_init_64.c:254 [inline] > kasan_die_handler.cold+0x11/0x23 arch/x86/mm/kasan_init_64.c:249 > notifier_call_chain+0xc2/0x230 kernel/notifier.c:95 > __atomic_notifier_call_chain+0xa6/0x1a0 kernel/notifier.c:185 > atomic_notifier_call_chain kernel/notifier.c:195 [inline] > notify_die+0xfb/0x180 kernel/notifier.c:551 > do_general_protection+0x13d/0x300 arch/x86/kernel/traps.c:558 > general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1181 > RIP: 0010:cgroup_rstat_updated+0x174/0x2f0 kernel/cgroup/rstat.c:64 > Code: 00 fc ff df 48 8b 45 c0 48 c1 e8 03 4c 01 f8 48 89 45 c8 eb 60 e8 6c > e1 05 00 49 8d 7c 24 30 48 8b 55 d0 49 89 f9 49 c1 e9 03 <43> 80 3c 39 00 > 0f 85 00 01 00 00 49 8b 7c 24 30 48 89 7a 38 49 8d > RSP: 0018:ffff8880ae809c08 EFLAGS: 00010006 > RAX: ffff88809378a480 RBX: 0000000000000000 RCX: ffffffff8159c5ca > RDX: ffff8880ae800000 RSI: ffffffff816ca374 RDI: 47ff8883313e8861 > RBP: ffff8880ae809c58 R08: 0000000000000004 R09: 08fff1106627d10c > R10: ffffed1015d0136d R11: 0000000000000003 R12: 47ff8883313e8831 > R13: ffff88807b60a280 R14: ffffffff8626cbf5 R15: dffffc0000000000 > cgroup_base_stat_cputime_account_end.isra.0+0x1d/0x60 kernel/cgroup/rstat.c:361 > __cgroup_account_cputime_field+0xd3/0x130 kernel/cgroup/rstat.c:395 > cgroup_account_cputime_field include/linux/cgroup.h:797 [inline] > task_group_account_field kernel/sched/cputime.c:109 [inline] > account_system_index_time+0x1f7/0x390 kernel/sched/cputime.c:172 > irqtime_account_process_tick.isra.0+0x386/0x490 kernel/sched/cputime.c:389 > account_process_tick+0x27f/0x350 kernel/sched/cputime.c:484 > update_process_times+0x25/0x80 kernel/time/timer.c:1637 > tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:167 > tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1296 > __run_hrtimer kernel/time/hrtimer.c:1389 [inline] > __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1451 > hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1509 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1068 [inline] > smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1093 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:828 > </IRQ> > Rebooting in 86400 seconds.. ==================================== > general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1181 > RIP: 0010:cgroup_rstat_updated+0x174/0x2f0 kernel/cgroup/rstat.c:64 Is rcu needed to avoid the gpf above while walking up the cgroup tree? --- a/kernel/cgroup/rstat.c +++ b/kernel/cgroup/rstat.c @@ -47,6 +47,7 @@ void cgroup_rstat_updated(struct cgroup return; raw_spin_lock_irqsave(cpu_lock, flags); + rcu_read_lock(); /* put @cgrp and all ancestors on the corresponding updated lists */ for (parent = cgroup_parent(cgrp); parent; @@ -65,6 +66,7 @@ void cgroup_rstat_updated(struct cgroup prstatc->updated_children = cgrp; } + rcu_read_unlock(); raw_spin_unlock_irqrestore(cpu_lock, flags); } EXPORT_SYMBOL_GPL(cgroup_rstat_updated); --
