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SubjectRe: [PATCH] x86/numa: kernel stack corruption fix
On 2015/4/1 15:41, Dave Young wrote:

> On 04/01/15 at 03:27pm, Xishi Qiu wrote:
>> On 2015/4/1 13:11, Dave Young wrote:
>>
>>> Ccing Xishi Qiu who wrote the clear_kernel_node_hotplug code.
>>>
>>> On 04/01/15 at 12:53pm, Dave Young wrote:
>>>> I got below kernel panic during kdump test on Thinkpad T420 laptop:
>>>>
>>>> [ 0.000000] No NUMA configuration found
>>>> [ 0.000000] Faking a node at [mem 0x0000000000000000-0x0000000037ba4fff]
>>>> [ 0.000000] Kernel panic - not syncing: stack-protector: Kernel stack is cor
>>>> upted in: ffffffff81d21910 r
>>>> [ 0.000000]
>>>> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.0.0-rc6+ #44
>>>> [ 0.000000] Hardware name: LENOVO 4236NUC/4236NUC, BIOS 83ET76WW (1.46 ) 07/
>>>> 5/2013 0
>>>> [ 0.000000] 0000000000000000 c70296ddd809e4f6 ffffffff81b67ce8 ffffffff817c
>>>> a26 2
>>>> [ 0.000000] 0000000000000000 ffffffff81a61c90 ffffffff81b67d68 ffffffff817b
>>>> 8d2 c
>>>> [ 0.000000] 0000000000000010 ffffffff81b67d78 ffffffff81b67d18 c70296ddd809
>>>> 4f6 e
>>>> [ 0.000000] Call Trace:
>>>> [ 0.000000] [<ffffffff817c2a26>] dump_stack+0x45/0x57
>>>> [ 0.000000] [<ffffffff817bc8d2>] panic+0xd0/0x204
>>>> [ 0.000000] [<ffffffff81d21910>] ? numa_clear_kernel_node_hotplug+0xe6/0xf2
>>>> [ 0.000000] [<ffffffff8107741b>] __stack_chk_fail+0x1b/0x20
>>>> [ 0.000000] [<ffffffff81d21910>] numa_clear_kernel_node_hotplug+0xe6/0xf2
>>>> [ 0.000000] [<ffffffff81d21e5d>] numa_init+0x1a5/0x520
>>>> [ 0.000000] [<ffffffff81d222b1>] x86_numa_init+0x19/0x3d
>>>> [ 0.000000] [<ffffffff81d22460>] initmem_init+0x9/0xb
>>>> [ 0.000000] [<ffffffff81d0d00c>] setup_arch+0x94f/0xc82
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff817bd0bb>] ? printk+0x55/0x6b
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff81d05d9b>] start_kernel+0xe8/0x4d6
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff81d055ee>] x86_64_start_reservations+0x2a/0x2c
>>>> [ 0.000000] [<ffffffff81d05751>] x86_64_start_kernel+0x161/0x184
>>>> [ 0.000000] ---[ end Kernel panic - not syncing: stack-protector: Kernel sta
>>>> k is corrupted in: ffffffff81d21910 c
>>>> [ 0.000000]
>>>> PANIC: early exception 0d rip 10:ffffffff8105d2a6 error 7eb cr2 ffff8800371dd00
>>>> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.0.0-rc6+ #44 0
>>>> [ 0.000000] Hardware name: LENOVO 4236NUC/4236NUC, BIOS 83ET76WW (1.46 ) 07/
>>>> 5/2013 0
>>>> [ 0.000000] 0000000000000000 c70296ddd809e4f6 ffffffff81b67c60 ffffffff817c
>>>> a26 2
>>>> [ 0.000000] 0000000000000096 ffffffff81a61c90 ffffffff81b67d68 fffffff00000
>>>> 084 0000000000000a0d 0000000000000a00 0
>>>> [ 0.000000] Call Trace:
>>>> [ 0.000000] [<ffffffff817c2a26>] dump_stack+0x45/0x57
>>>> [ 0.000000] [<ffffffff81d051b0>] early_idt_handler+0x90/0xb7
>>>> [ 0.000000] [<ffffffff8105d2a6>] ? native_irq_enable+0x6/0x10
>>>> [ 0.000000] [<ffffffff817bc9c5>] ? panic+0x1c3/0x204
>>>> [ 0.000000] [<ffffffff81d21910>] ? numa_clear_kernel_node_hotplug+0xe6/0xf2
>>>> [ 0.000000] [<ffffffff8107741b>] __stack_chk_fail+0x1b/0x20
>>>> [ 0.000000] [<ffffffff81d21910>] numa_clear_kernel_node_hotplug+0xe6/0xf2
>>>> [ 0.000000] [<ffffffff81d21e5d>] numa_init+0x1a5/0x520
>>>> [ 0.000000] [<ffffffff81d222b1>] x86_numa_init+0x19/0x3d
>>>> [ 0.000000] [<ffffffff81d22460>] initmem_init+0x9/0xb
>>>> [ 0.000000] [<ffffffff81d0d00c>] setup_arch+0x94f/0xc82
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff817bd0bb>] ? printk+0x55/0x6b
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff81d05d9b>] start_kernel+0xe8/0x4d6
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120
>>>> [ 0.000000] [<ffffffff81d055ee>] x86_64_start_reservations+0x2a/0x2c
>>>> [ 0.000000] [<ffffffff81d05751>] x86_64_start_kernel+0x161/0x184
>>>> [ 0.000000] RIP 0x46
>>>>
>>>> This is caused by writing over end of numa mask bitmap.
>>>>
>>>> numa_clear_kernel_node try to set node id in a mask bitmap, it iterating all
>>>> reserved region and assume every regions have valid nid. It is not true because
>>>> There's an exception for graphic memory quirks. see function trim_snb_memory
>>>> in arch/x86/kernel/setup.c
>>>>
>>>> It is easily to reproduce the bug in kdump kernel because kdump kernel use
>>>> prereserved memory instead of whole memory, but kexec pass other reserved memory
>>>> ranges to 2nd kernel as well. like below in my test:
>>>> kdump kernel ram 0x2d000000 - 0x37bfffff
>>>> One of the reserved regions: 0x40000000 - 0x40100000
>>>>
>>>> The above reserved region includes 0x40004000, a page excluded in
>>>> trim_snb_memory. For this memblock reserved region the nid is not set it is
>>>> still default value MAX_NUMNODES. later node_set callback will set bit
>>>> MAX_NUMNODES in nodemask bitmap thus stack corruption happen.
>>>>
>>
>> Hi Dave,
>>
>> Is it means, first reserved region 0x40000000 - 0x40100000, then boot the kdump
>> kernel, so this region is not include in "numa_meminfo", and memblock.reserved
>> (0x40004000) is still MAX_NUMNODES from trim_snb_memory().
>
> Right, btw, I booted kdump kernel with numa=off for saving memory.
>
> I suspect it will also be reproduced with mem=XYZ with normal kernel.
>

cc Tang Chen, numa_clear_kernel_node_hotplug() is original written by him.

Hi Dave,
I tested the problem, and find the kdump's "numa_meminfo" is the same as the first
kernel. I did not set "numa=off" in kdump kernel, maybe this will lead to the
difference of "numa_meminfo"

Thanks,
Xishi Qiu

>>
>> numa_clear_kernel_node_hotplug
>> {
>> ...
>> for (i = 0; i < numa_meminfo.nr_blks; i++) {
>> struct numa_memblk *mb = &numa_meminfo.blk[i];
>>
>> memblock_set_node(mb->start, mb->end - mb->start,
>> &memblock.reserved, mb->nid); // this will not reset 0x40004000's node, right?
>> }
>> ...
>> }
>>
>> Thanks
>> Xishi Qiu
>>





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