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Date: Wed, 1 Apr 2015 17:17:38 +0800
From: Dave Young <dyoung@redhat.com>
To: Xishi Qiu <qiuxishi@huawei.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de,
        bhe@redhat.com, mingo@redhat.com, hpa@zytor.com,
        akpm@linux-foundation.org, Tang Chen <tangchen@cn.fujitsu.com>
Subject: Re: [PATCH] x86/numa: kernel stack corruption fix
Message-ID: <20150401091738.GI8680@dhcp-128-53.nay.redhat.com>
References: <20150401045346.GA3461@dhcp-16-198.nay.redhat.com>
 <20150401051133.GC8680@dhcp-128-53.nay.redhat.com>
 <551B9DD7.5010603@huawei.com>
 <20150401074120.GF8680@dhcp-128-53.nay.redhat.com>
 <551BAA6D.30104@huawei.com>
 <551BADAE.4080404@huawei.com>
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On 04/01/15 at 04:34pm, Xishi Qiu wrote:
> On 2015/4/1 16:21, Xishi Qiu wrote:
> 
> > 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"
> >
> 
> Hi Dave,
> 
> I find the reason, it's "dummy_numa_init() -> numa_add_memblk(0, 0, PFN_PHYS(max_pfn));",
> this lead to the difference of "numa_meminfo" when set "numa=off".
> 
> However we should fix the bug when set "numa=off".

So do you means MAXPFN should include non system ram region at the end?

The case like below, I believe max_pfn is set to the end of system ram currently:
[what ever] [ system ram ] [ bios reserved region ]

Thanks
Dave
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