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Date: Wed, 1 Apr 2015 15:41:20 +0800
From: Dave Young <dyoung@...hat.com>
To: Xishi Qiu <qiuxishi@...wei.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, tglx@...utronix.de,
bhe@...hat.com, mingo@...hat.com, hpa@...or.com,
akpm@...ux-foundation.org
Subject: Re: [PATCH] x86/numa: kernel stack corruption fix
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.
>
> 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
>
> >> Fixing this by adding a check, do not call node_set in case nid is MAX_NUMNODES.
> >>
> >> Signed-off-by: Dave Young <dyoung@...hat.com>
> >> ---
> >> arch/x86/mm/numa.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> --- linux.orig/arch/x86/mm/numa.c
> >> +++ linux/arch/x86/mm/numa.c
> >> @@ -484,7 +484,8 @@ static void __init numa_clear_kernel_nod
> >>
> >> /* Mark all kernel nodes. */
> >> for_each_memblock(reserved, r)
> >> - node_set(r->nid, numa_kernel_nodes);
> >> + if (r->nid != MAX_NUMNODES)
> >> + node_set(r->nid, numa_kernel_nodes);
> >>
> >> /* Clear MEMBLOCK_HOTPLUG flag for memory in kernel nodes. */
> >> for (i = 0; i < numa_meminfo.nr_blks; i++) {
> >>
> >
> > .
> >
>
>
>
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