Re: 4.0.0-rc1-next-20150303: cgroup: BUG: unable to handle kernel NULL pointer dereference at

[Zefan Li <lizefan@huawei.com>]

Caused by this commit:

295458e67284f57d1 cgroup: call cgroup_subsys->bind on cgroup subsys initialization

cpuset_init() is called after cgroup_init(), so when cgroup_init() calls cpuset_bind()
top_cpuset.cpus_allowed is NULL.

I'll send out a fix soon.

On 2015/3/4 13:17, Ming Lei wrote:
> Hi Guys,
> 
> [    0.014166] BUG: unable to handle kernel NULL pointer dereference
> at           (null)^M
> [    0.014920] IP: [<ffffffff810ab011>] cpumask_copy+0x17/0x1a^M
> [    0.015000] PGD 0 ^M
> [    0.015000] Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M
> [    0.015000] Dumping ftrace buffer:^M
> [    0.015000]    (ftrace buffer empty)^M
> [    0.015000] Modules linked in:^M
> [    0.015000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
> 4.0.0-rc1-next-20150303 #123^M
> [    0.015000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS Bochs 01/01/2011^M
> [    0.015000] task: ffffffff81a10460 ti: ffffffff81a00000 task.ti:
> ffffffff81a00000^M
> [    0.015000] RIP: 0010:[<ffffffff810ab011>]  [<ffffffff810ab011>]
> cpumask_copy+0x17/0x1a^M
> [    0.015000] RSP: 0000:ffffffff81a03f00  EFLAGS: 00010002^M
> [    0.015000] RAX: ffffffff81e7aa80 RBX: ffffffff81a96060 RCX:
> 0000000000000008^M
> [    0.015000] RDX: ffffffff81a96000 RSI: ffffffff81b19f10 RDI:
> 0000000000000000^M
> [    0.015000] RBP: ffffffff81a03f18 R08: 00000000000000d0 R09:
> ffff880235138120^M
> [    0.015000] R10: 0000000000000000 R11: 0000000000017078 R12:
> ffffffff81a94dc0^M
> [    0.015000] R13: ffffffff81e7aba0 R14: 0000000000000000 R15:
> 0000000000000000^M
> [    0.015000] FS:  0000000000000000(0000) GS:ffff88023ec00000(0000)
> knlGS:0000000000000000^M
> [    0.015000] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M
> [    0.015000] CR2: 0000000000000000 CR3: 0000000001a0b000 CR4:
> 00000000000006b0^M
> [    0.015000] Stack:^M
> [    0.015000]  ffffffff810ab202 ffffffff81a96000 ffffffff81a952d0
> ffffffff81a03f68^M
> [    0.015000]  ffffffff81b557ae 0000000000000000 ffffffff81a95fa0
> ffffffffffffffff^M
> [    0.015000]  ffffffffffffffff ffffffff81bc88d0 ffff88023efa4480
> ffffffff81bd02c0^M
> [    0.015000] Call Trace:^M
> [    0.015000]  [<ffffffff810ab202>] ? cpuset_bind+0x50/0x99^M
> [    0.015000]  [<ffffffff81b557ae>] cgroup_init+0x1ef/0x27b^M
> [    0.015000]  [<ffffffff81b39e7f>] start_kernel+0x3fa/0x43f^M
> [    0.015000]  [<ffffffff81b3987d>] ? set_init_arg+0x55/0x55^M
> [    0.015000]  [<ffffffff81b39489>] x86_64_start_reservations+0x2a/0x2c^M
> [    0.015000]  [<ffffffff81b3958d>] x86_64_start_kernel+0x102/0x106^M
> [    0.015000] Code: 15 29 04 a7 00 48 89 e5 e8 3b 4d 20 00 85 c0 0f
> 95 c0 5d c3 8b 0d 14 04 a7 00 55 48 89 e5 5d 48 83 c1 3f 48 c1 e9 06
> 48 c1 e1 03 <f3> a4 c3 55 8b 35 f9 03 a7 00 48 89 e5 e8 7f 4c 20 00 85
> c0 0f ^M
> [    0.015000] RIP  [<ffffffff810ab011>] cpumask_copy+0x17/0x1a^M
> [    0.015000]  RSP <ffffffff81a03f00>^M
> [    0.015000] CR2: 0000000000000000^M
> [    0.015000] ---[ end trace 15a4fd3fb5107ec6 ]---^M
> [    0.015000] Kernel panic - not syncing: Attempted to kill the idle task!^M
> [    0.015000] Dumping ftrace buffer:^M
> [    0.015000]    (ftrace buffer empty)^M
> 
> 
> Thanks,
> Ming Lei
> .
>