Date:   Thu, 13 Aug 2020 17:29:51 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     syzbot <syzbot+35d35ef677516d65bdda@...kaller.appspotmail.com>,
        Roman Gushchin <guro@...com>
Cc:     akpm@...ux-foundation.org, cgroups@...r.kernel.org,
        hannes@...xchg.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, syzkaller-bugs@...glegroups.com,
        vdavydov.dev@...il.com
Subject: Re: upstream boot error: WARNING in mem_cgroup_css_alloc

On Thu 13-08-20 12:44:16, Michal Hocko wrote:
> This smells like 3e38e0aaca9e ("mm: memcg: charge memcg percpu memory to
> the parent cgroup"). 

This should be addressed by http://lkml.kernel.org/r/20200813152033.GA701678@cmpxchg.org
I haven't noticed this is panic_on_warn earlier.
 
> On Thu 13-08-20 02:47:26, syzbot wrote:
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    dc06fe51 Merge tag 'rtc-5.9' of git://git.kernel.org/pub/s..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=12d34bd6900000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=9c89856ae5fc8b6
> > dashboard link: https://syzkaller.appspot.com/bug?extid=35d35ef677516d65bdda
> > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+35d35ef677516d65bdda@...kaller.appspotmail.com
> > 
> > mem auto-init: stack:off, heap alloc:on, heap free:off
> > Memory: 6461180K/7863916K available (116743K kernel code, 17665K rwdata, 21624K rodata, 2792K init, 23940K bss, 1402480K reserved, 0K cma-reserved)
> > Running RCU self tests
> > rcu: Preemptible hierarchical RCU implementation.
> > rcu: 	RCU lockdep checking is enabled.
> > rcu: 	RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=2.
> > rcu: 	RCU callback double-/use-after-free debug enabled.
> > rcu: 	RCU debug extended QS entry/exit.
> > 	All grace periods are expedited (rcu_expedited).
> > 	Trampoline variant of Tasks RCU enabled.
> > rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
> > rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
> > NR_IRQS: 4352, nr_irqs: 440, preallocated irqs: 16
> > random: get_random_bytes called from boot_init_stack_canary arch/x86/include/asm/stackprotector.h:80 [inline] with crng_init=0
> > random: get_random_bytes called from start_kernel+0x23b/0x46a init/main.c:957 with crng_init=0
> > Console: colour VGA+ 80x25
> > printk: console [ttyS0] enabled
> > printk: console [ttyS0] enabled
> > printk: bootconsole [earlyser0] disabled
> > printk: bootconsole [earlyser0] disabled
> > Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
> > ... MAX_LOCKDEP_SUBCLASSES:  8
> > ... MAX_LOCK_DEPTH:          48
> > ... MAX_LOCKDEP_KEYS:        8192
> > ... CLASSHASH_SIZE:          4096
> > ... MAX_LOCKDEP_ENTRIES:     32768
> > ... MAX_LOCKDEP_CHAINS:      65536
> > ... CHAINHASH_SIZE:          32768
> >  memory used by lock dependency info: 6301 kB
> >  memory used for stack traces: 4224 kB
> >  per task-struct memory footprint: 1920 bytes
> > mempolicy: Enabling automatic NUMA balancing. Configure with numa_balancing= or the kernel.numa_balancing sysctl
> > ACPI: Core revision 20200717
> > APIC: Switch to symmetric I/O mode setup
> > x2apic enabled
> > Switched APIC routing to physical x2apic.
> > ..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1
> > clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x212735223b2, max_idle_ns: 440795277976 ns
> > Calibrating delay loop (skipped) preset value.. 4600.00 BogoMIPS (lpj=23000000)
> > pid_max: default: 32768 minimum: 301
> > LSM: Security Framework initializing
> > LSM: security= is ignored because it is superseded by lsm=
> > Yama: becoming mindful.
> > TOMOYO Linux initialized
> > AppArmor: AppArmor initialized
> > LSM support for eBPF active
> > Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, vmalloc)
> > Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes, vmalloc)
> > Mount-cache hash table entries: 16384 (order: 5, 131072 bytes, vmalloc)
> > Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes, vmalloc)
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 0 at mm/memcontrol.c:5226 memalloc_unuse_memcg include/linux/sched/mm.h:331 [inline]
> > WARNING: CPU: 0 PID: 0 at mm/memcontrol.c:5226 mem_cgroup_css_alloc+0x535/0x1c30 mm/memcontrol.c:5285
> > Kernel panic - not syncing: panic_on_warn set ...
> > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.8.0-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> >  __dump_stack lib/dump_stack.c:77 [inline]
> >  dump_stack+0x18f/0x20d lib/dump_stack.c:118
> >  panic+0x2e3/0x75c kernel/panic.c:231
> >  __warn.cold+0x20/0x4a kernel/panic.c:600
> >  report_bug+0x1bd/0x210 lib/bug.c:198
> >  handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234
> >  exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254
> >  asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
> > RIP: 0010:mem_cgroup_alloc mm/memcontrol.c:5226 [inline]
> > RIP: 0010:mem_cgroup_css_alloc+0x535/0x1c30 mm/memcontrol.c:5284
> > Code: 01 00 48 8d bb 28 14 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 74 81 e8 e0 00 c2 f9 e9 77 ff ff ff <0f> 0b e9 21 fc ff ff 48 89 ef e8 bc 28 c7 f9 48 b8 00 00 00 00 00
> > RSP: 0000:ffffffff89a07e20 EFLAGS: 00010246
> > RAX: dffffc0000000000 RBX: ffffffff89a99dc0 RCX: 1ffff110152b2028
> > RDX: 1ffffffff135363d RSI: ffffffff83b0f2c2 RDI: ffffffff89a9b1e8
> > RBP: ffff8880a9590000 R08: 0000000000000001 R09: ffff88821b801aef
> > R10: 0000000000000000 R11: ffffffff810000d4 R12: ffffffff8ab224b4
> > R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff8ab224d0
> >  cgroup_init_subsys+0x215/0x4d7 kernel/cgroup/cgroup.c:5587
> >  cgroup_init+0x359/0xa63 kernel/cgroup/cgroup.c:5713
> >  start_kernel+0x426/0x46a init/main.c:1035
> >  secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243
> > Rebooting in 86400 seconds..
> > 
> > 
> > ---
> > 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@...glegroups.com.
> > 
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> -- 
> Michal Hocko
> SUSE Labs

-- 
Michal Hocko
SUSE Labs

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