by YASUAKI ISHIMATSU

[permalink] [raw]

Subject: Re: [PATCH] x86/numa: kernel stack corruption fix

Hi Dave,

On Tue, 7 Apr 2015 11:33:55 +0800
Dave Young <[email protected]> wrote:

> On 04/06/15 at 07:26am, Yasuaki Ishimatsu wrote:
> > Hi,
> >
> > On Fri, 3 Apr 2015 15:15:13 +0800
> > Dave Young <[email protected]> wrote:
> >
> > > Hi,
> > >
> > > On 04/02/15 at 12:36pm, Yasuaki Ishimatsu wrote:
> > > >
> > > > On Wed, 1 Apr 2015 12:53:46 +0800
> > > > Dave Young <[email protected]> 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.
> > > > >
> > > > > Fixing this by adding a check, do not call node_set in case nid is MAX_NUMNODES.
> > > > >
> > > > > Signed-off-by: Dave Young <[email protected]>
> > > > > ---
> > > >
> > > > Looks good to me.
> > > >
> > > > Reviewed-by: Yasuaki Ishimatsu <[email protected]>
> > >
> >
> > > Per suggestion from Xishi Qiu, I would like to add below comment in code and repost
> > > Could I carry with your Reviewed-by line?
> > >
> > > /* In case booting with numa=off and only using part of system ram
> > > * ie. mem=nn[kMG] or in kdump kernel, numa_meminfo may not include all the
> > > * memblock.reserved memory because trim_snb_memory() reserves specific pages
> > > * for Sandy Bridge graphics. */
> >
> > I don't think the issue is related to numa=off. If we use numa=off,
> > all memory ranges which are informed by e820 are managed to Node 0.
> >
> > The issue occurs when reserved memory ranges are not included
> > in system ram which informed by e820.
>
> Maybe in theory it is possible that it occurs without numa=off so that numa
> meminfo does not include some reserved regions, but I think I can only
> reproduce it with numa=off.
>
> But ok, I can use the comment below instead:
>

> /*
> * In case booting with mem=nn[kMG] or in kdump kernel, numa_meminfo may not
> * include all the memblock.reserved memory ranges because trim_snb_memory()
> * reserves specific pages for Sandy Bridge graphics.
> */

Looks good to me.

Feel free to add my reviewed by.

Thanks,
Yasuaki Ishimatsu

>
> Thanks
> Dave