[PATCH] makedumpfile: memset() in cyclic bitmap initialization introduce segment fault
HATAYAMA Daisuke
d.hatayama at jp.fujitsu.com
Wed Dec 25 19:10:41 EST 2013
(2013/12/20 21:58), Lisa Mitchell wrote:
> On Fri, 2013-12-20 at 14:13 +0000, Vivek Goyal wrote:
>> On Fri, Dec 20, 2013 at 10:08:08AM +0900, HATAYAMA Daisuke wrote:
>>
>> [..]
>>>
>>>> cat /proc/iomem:
>>>> 00000000-00000fff : reserved
>>>> 00001000-0009ffff : System RAM
>>>> 000a0000-000bffff : PCI Bus 0000:00
>>>> 000f0000-000fffff : System ROM
>>>> 00100000-3d162017 : System RAM
>>>> 01000000-015cab9b : Kernel code
>>>> 015cab9c-019beb3f : Kernel data
>>>> 01b4f000-01da9fff : Kernel bss
>>>> 30000000-37ffffff : Crash kernel
>>>> 3d162018-3d171e57 : System RAM
>>>> 3d171e58-3d172017 : System RAM
>>>> 3d172018-3d17ae57 : System RAM
>>>> 3d17ae58-3dc10fff : System RAM
>>>
>>> this part is consecutive but somehow is divided into 4 entries.
>>> You called your environment as ``EFI virtual machine'', could you tell
>>> me precisely what it mean? qemu/KVM or VMware guest system? I do want
>>> to understand how this kind of memory map was created. I think this
>>> kind of memory mapping is odd and I guess this is caused by the fact
>>> that the system is a virtual environment.
>>>
>>> And for Vivek, this case is a concrete example of multiple RAM entries
>>> appearing in a single page I suspected in the mmap failure patch,
>>> although these entries are consecutive in physical address and can be
>>> represented by a single entry by merging them in a single entry. But
>>> then it seems to me that there could be more odd case that multiple
>>> RAM entries but not consecutive. I again think this should be addressed
>>> in the patch for the mmap failure issue. How do you think?
>>
>> Hi Hatayama,
>>
>> This indeed looks very odd. See if a very small number of systems have it,
>> the only thing we will do is allocate extra page in second kernel for
>> a memory range. It will not make mmap() fail. So it is just a matter of
>> optimization.
>>
>> Given the fact I have not seen many systems with this anomaly, I am not
>> too worried about it even if you don't this optimization in your patch
>> series. We can always take care of it later if need be.
>>
>> At the same time, if you feel strongly about it and want to fix it in
>> same patch series, I don't mind.
>>
>> Thanks
>> Vivek
>
> Did I get this same segmentation fault? It happened a few times on a
> 3.10 based kernel on a large EFI based system , but then hasn't repeated
> in further testing on this machine. This machine had no virtualization
> active. Here is partial console log of dump process:
>
> =============================================================================
>
> kdump: dump target is /dev/mapper/mpathc3
> kdump: saving to /sysroot//var/crash/127.0.0.1-2013.11.11-09:58:20/
> kdump: saving vmcore-dmesg.txt
> kdump: saving vmcore-dmesg.txt complete
> kdump: saving vmcore
> [ 46.017827] scsi 20:0:0:0: Direct-Access Geek Squad
> 8192 PQ: 0 ANSI: 0 CCS
> [ 46.027849] scsi 20:0:0:0: alua: supports implicit and explicit TPGS
> [ 46.035641] scsi 20:0:0:0: alua: No target port descriptors found
> [ 46.042491] scsi 20:0:0:0: alua: not attached
> [ 46.048152] sd 20:0:0:0: [sdak] 15663104 512-byte logical blocks:
> (8.01 GB/7.46 GiB)
> [ 46.057892] sd 20:0:0:0: [sdak] Write Protect is off
> [ 46.064516] sd 20:0:0:0: [sdak] No Caching mode page present
> [ 46.070877] sd 20:0:0:0: [sdak] Assuming drive cache: write through
> [ 46.081639] sd 20:0:0:0: [sdak] No Caching mode page present
> [ 46.088035] sd 20:0:0:0: [sdak] Assuming drive cache: write through
> [ 46.107070] sdak: sdak1 sdak2 sdak3
> [ 46.114636] sd 20:0:0:0: [sdak] No Caching mode page present
> [ 46.121021] sd 20:0:0:0: [sdak] Assuming drive cache: write through
> [ 46.128060] sd 20:0:0:0: [sdak] Attached SCSI removable disk
>
> Excluding unnecessary pages : [ 0 %]
> Excluding unnecessary
> sary pages : [ 0 %]
> Excluding unnecessary pages : [ 0
> %]
> Excluding unnecessary pages : [ 8 %]
> Excluding unnecessary
> pages : [ 15 %]
> Excluding unnecessary pages : [ 21 %] [
> 53.800116] usb 4-1.6: device descriptor read/64, error -110
>
> Excluding unnecessary pages : [ 28 %]
> Excluding unnecessary
> pages : [ 34 %]
> Excluding unnecessary pages : [ 41 %]
> Excluding unnecessary pages : [100 %] [ 59.174433] scsi
> 18:0:0:0: Enclosure HP P2000 G3 FC T240 PQ: 0 ANSI: 5
> [ 59.183866] scsi 18:0:0:0: alua: supports implicit TPGS
> [ 59.190190] scsi 18:0:0:0: alua: port group 01 rel port 05
> [ 59.197694] scsi 18:0:0:0: alua: transition timeout set to 60 seconds
>
> ......
>
> [ 76.968265] makedumpfile[1291]: segfault at 7f5ac0c39010 ip
> 00000000004297fd sp 00007fff691683a0 error 4 in makedumpfile[400000
> +46000]
> //lib/dracut/hooks/pre-pivot/9999-kdump.sh: line 88: 1291 Segmentation
> fault [ 76.996926] sd 18:0:1:51: [sdao] Synchronizing SCSI cache
> $CORE_COLLECT[ 77.003416] sd 18:0:1:50: [sdan] Synchronizing SCSI
> cache
> OR /proc/vmcore [ 77.010991] sd 18:0:0:51: [sdam] Synchronizing SCSI
> cache
> $_mp/$KDUMP_PATH[ 77.018590] sd 18:0:0:50: [sdal] Synchronizing SCSI
> cache
> /$HOST_IP-$DATED[ 77.026611] sd 14:0:1:71: [sdaj] Synchronizing SCSI
> cache
> IR/vmcore-incomp[ 77.033849] sd 14:0:1:70: [sdai] Synchronizing SCSI
> cache
> lete
> kdump: sav[ 77.041467] sd 14:0:0:71: [sdah] Synchronizing SCSI cache
> ing vmcore faile[ 77.049146] sd 14:0:0:70: [sdag] Synchronizing SCSI
> cached
> Rebooting.
>
>
> =======================================================================
>
> I do not have a current /proc/iomem output to go with the above.
> However this dump was nr_cpus=8 during crashkernel boot, with a 3.10
> kernel with Daisuke's version 4 of Daisuke Hatayama's patch to allow
> multi-cpu crashkernel boot.
>
> I have the efi memory map displayed as Linux booted, before this dump if
> that helps
>
> 0.000000] efi: ACPI=0x73ffe000 ACPI 2.0=0x73ffe014 SMBIOS=0x72ef8000
> [ 0.000000] efi: mem00: type=3, attr=0xf,
> range=[0x0000000000000000-0x0000000000001000) (0MB)
> [ 0.000000] efi: mem01: type=2, attr=0xf,
> range=[0x0000000000001000-0x0000000000004000) (0MB)
> [ 0.000000] efi: mem02: type=7, attr=0xf,
> range=[0x0000000000004000-0x000000000008e000) (0MB)
> [ 0.000000] efi: mem03: type=0, attr=0xf,
> range=[0x000000000008e000-0x0000000000090000) (0MB)
> [ 0.000000] efi: mem04: type=7, attr=0xf,
> range=[0x0000000000090000-0x00000000000a0000) (0MB)
> [ 0.000000] efi: mem05: type=7, attr=0xf,
> range=[0x0000000000100000-0x0000000001000000) (15MB)
> [ 0.000000] efi: mem06: type=2, attr=0xf,
> range=[0x0000000001000000-0x0000000002268000) (18MB)
> [ 0.000000] efi: mem07: type=7, attr=0xf,
> range=[0x0000000002268000-0x0000000010000000) (221MB)
> [ 0.000000] efi: mem08: type=3, attr=0xf,
> range=[0x0000000010000000-0x0000000010066000) (0MB)
> [ 0.000000] efi: mem09: type=7, attr=0xf,
> range=[0x0000000010066000-0x0000000029dfb000) (413MB)
> [ 0.000000] efi: mem10: type=2, attr=0xf,
> range=[0x0000000029dfb000-0x0000000039ba0000) (253MB)
> [ 0.000000] efi: mem11: type=4, attr=0xf,
> range=[0x0000000039ba0000-0x000000003e179000) (69MB)
> [ 0.000000] efi: mem12: type=3, attr=0xf,
> range=[0x000000003e179000-0x000000003e55c000) (3MB)
> [ 0.000000] efi: mem13: type=4, attr=0xf,
> range=[0x000000003e55c000-0x000000003e567000) (0MB)
> [ 0.000000] efi: mem14: type=3, attr=0xf,
> range=[0x000000003e567000-0x000000003e6e9000) (1MB)
> [ 0.000000] efi: mem15: type=4, attr=0xf,
> range=[0x000000003e6e9000-0x000000003e6f4000) (0MB)
> [ 0.000000] efi: mem16: type=3, attr=0xf,
> range=[0x000000003e6f4000-0x000000003e88f000) (1MB)
> [ 0.000000] efi: mem17: type=4, attr=0xf,
> range=[0x000000003e88f000-0x000000003e8f4000) (0MB)
> [ 0.000000] efi: mem18: type=3, attr=0xf,
> range=[0x000000003e8f4000-0x000000003e9cf000) (0MB)
> [ 0.000000] efi: mem19: type=4, attr=0xf,
> range=[0x000000003e9cf000-0x000000003e9d0000) (0MB)
> [ 0.000000] efi: mem20: type=3, attr=0xf,
> range=[0x000000003e9d0000-0x000000003ee9d000) (4MB)
> [ 0.000000] efi: mem21: type=4, attr=0xf,
> range=[0x000000003ee9d000-0x000000003ef9b000) (0MB)
> [ 0.000000] efi: mem22: type=0, attr=0xf,
> range=[0x000000003ef9b000-0x000000003efab000) (0MB)
> [ 0.000000] efi: mem23: type=4, attr=0xf,
> range=[0x000000003efab000-0x000000006ba1b000) (714MB)
> [ 0.000000] efi: mem24: type=10, attr=0xf,
> range=[0x000000006ba1b000-0x000000006ca1b000) (16MB)
> [ 0.000000] efi: mem25: type=4, attr=0xf,
> range=[0x000000006ca1b000-0x00000000709ff000) (63MB)
> [ 0.000000] efi: mem26: type=7, attr=0xf,
> range=[0x00000000709ff000-0x0000000070a10000) (0MB)
> [ 0.000000] efi: mem27: type=2, attr=0xf,
> range=[0x0000000070a10000-0x0000000070c34000) (2MB)
> [ 0.000000] efi: mem28: type=7, attr=0xf,
> range=[0x0000000070c34000-0x0000000070c35000) (0MB)
> [ 0.000000] efi: mem29: type=2, attr=0xf,
> range=[0x0000000070c35000-0x0000000070dff000) (1MB)
> [ 0.000000] efi: mem30: type=7, attr=0xf,
> range=[0x0000000070dff000-0x0000000070fa9000) (1MB)
> [ 0.000000] efi: mem31: type=1, attr=0xf,
> range=[0x0000000070fa9000-0x00000000711ff000) (2MB)
> [ 0.000000] efi: mem32: type=7, attr=0xf,
> range=[0x00000000711ff000-0x000000007120e000) (0MB)
> [ 0.000000] efi: mem33: type=3, attr=0xf,
> range=[0x000000007120e000-0x00000000721ff000) (15MB)
> [ 0.000000] efi: mem34: type=6, attr=0x800000000000000f,
> range=[0x00000000721ff000-0x00000000725ff000) (4MB)
> [ 0.000000] efi: mem35: type=5, attr=0x800000000000000f,
> range=[0x00000000725ff000-0x0000000072dff000) (8MB)
> [ 0.000000] efi: mem36: type=0, attr=0xf,
> range=[0x0000000072dff000-0x0000000072eff000) (1MB)
> [ 0.000000] efi: mem37: type=10, attr=0xf,
> range=[0x0000000072eff000-0x0000000073eff000) (16MB)
> [ 0.000000] efi: mem38: type=9, attr=0xf,
> range=[0x0000000073eff000-0x0000000073fff000) (1MB)
> [ 0.000000] efi: mem39: type=4, attr=0xf,
> range=[0x0000000073fff000-0x000000007c000000) (128MB)
> [ 0.000000] efi: mem40: type=7, attr=0xf,
> range=[0x0000000100000000-0x0000001080000000) (63488MB)
> [ 0.000000] efi: mem41: type=7, attr=0xf,
> range=[0x0000020000000000-0x0000021000000000) (65536MB)
> [ 0.000000] efi: mem42: type=7, attr=0xf,
> range=[0x0000038000000000-0x0000039000000000) (65536MB)
> [ 0.000000] efi: mem43: type=7, attr=0xf,
> range=[0x0000050000000000-0x0000051000000000) (65536MB)
> [ 0.000000] efi: mem44: type=7, attr=0xf,
> range=[0x0000068000000000-0x0000069000000000) (65536MB)
> [ 0.000000] efi: mem45: type=7, attr=0xf,
> range=[0x0000080000000000-0x0000081000000000) (65536MB)
> [ 0.000000] efi: mem46: type=7, attr=0xf,
> range=[0x0000098000000000-0x0000099000000000) (65536MB)
> [ 0.000000] efi: mem47: type=7, attr=0xf,
> range=[0x00000b0000000000-0x00000b1000000000) (65536MB)
> [ 0.000000] efi: mem48: type=7, attr=0xf,
> range=[0x00000c8000000000-0x00000c9000000000) (65536MB)
> [ 0.000000] efi: mem49: type=7, attr=0xf,
> range=[0x00000e0000000000-0x00000e1000000000) (65536MB)
> [ 0.000000] efi: mem50: type=7, attr=0xf,
> range=[0x00000f8000000000-0x00000f9000000000) (65536MB)
> [ 0.000000] efi: mem51: type=7, attr=0xf,
> range=[0x0000110000000000-0x0000111000000000) (65536MB)
> [ 0.000000] efi: mem52: type=7, attr=0xf,
> range=[0x0000128000000000-0x0000129000000000) (65536MB)
> [ 0.000000] efi: mem53: type=7, attr=0xf,
> range=[0x0000140000000000-0x0000141000000000) (65536MB)
> [ 0.000000] efi: mem54: type=7, attr=0xf,
> range=[0x0000158000000000-0x0000159000000000) (65536MB)
> [ 0.000000] efi: mem55: type=7, attr=0xf,
> range=[0x0000170000000000-0x0000171000000000) (65536MB)
> [ 0.000000] efi: mem56: type=11, attr=0x8000000000000001,
> range=[0x0000000080000000-0x0000000090000000) (256MB)
> [ 0.000000] efi: mem57: type=11, attr=0x8000000000000001,
> range=[0x00000000fed1c000-0x00000000fed20000) (0MB)
> [ 0.000000] efi: mem58: type=11, attr=0x8000000000000001,
> range=[0x00000000ff000000-0x00000000ff200000) (2MB)
> [ 0.000000] efi: mem59: type=11, attr=0x8000000000000001,
> range=[0x00003fdfe0000000-0x00003fdff4000000) (320MB)
> [ 0.000000] efi: mem60: type=11, attr=0x8000000000000001,
> range=[0x00003fe060000000-0x00003fe074000000) (320MB)
> [ 0.000000] efi: mem61: type=11, attr=0x8000000000000001,
> range=[0x00003fe0e0000000-0x00003fe0f4000000) (320MB)
> [ 0.000000] efi: mem62: type=11, attr=0x8000000000000001,
> range=[0x00003fe160000000-0x00003fe174000000) (320MB)
> [ 0.000000] efi: mem63: type=11, attr=0x8000000000000001,
> range=[0x00003fe1e0000000-0x00003fe1f4000000) (320MB)
> [ 0.000000] efi: mem64: type=11, attr=0x8000000000000001,
> range=[0x00003fe260000000-0x00003fe274000000) (320MB)
> [ 0.000000] efi: mem65: type=11, attr=0x8000000000000001,
> range=[0x00003fe2e0000000-0x00003fe2f4000000) (320MB)
> [ 0.000000] efi: mem66: type=11, attr=0x8000000000000001,
> range=[0x00003fe360000000-0x00003fe374000000) (320MB)
> [ 0.000000] efi: mem67: type=11, attr=0x8000000000000001,
> range=[0x00003fe3e0000000-0x00003fe3f4000000) (320MB)
> [ 0.000000] efi: mem68: type=11, attr=0x8000000000000001,
> range=[0x00003fe460000000-0x00003fe474000000) (320MB)
> [ 0.000000] efi: mem69: type=11, attr=0x8000000000000001,
> range=[0x00003fe4e0000000-0x00003fe4f4000000) (320MB)
> [ 0.000000] efi: mem70: type=11, attr=0x8000000000000001,
> range=[0x00003fe560000000-0x00003fe574000000) (320MB)
> [ 0.000000] efi: mem71: type=11, attr=0x8000000000000001,
> range=[0x00003fe5e0000000-0x00003fe5f4000000) (320MB)
> [ 0.000000] efi: mem72: type=11, attr=0x8000000000000001,
> range=[0x00003fe660000000-0x00003fe674000000) (320MB)
> [ 0.000000] efi: mem73: type=11, attr=0x8000000000000001,
> range=[0x00003fe6e0000000-0x00003fe6f4000000) (320MB)
> [ 0.000000] efi: mem74: type=11, attr=0x8000000000000001,
> range=[0x00003fe760000000-0x00003fe774000000) (320MB)
> [ 0.000000] efi: mem75: type=11, attr=0x8000000000000001,
> range=[0x00003fe7e0000000-0x00003fe7f4000000) (320MB)
>
This is an original memory map passed to by UEFI. kexec tool
uses /proc/iomem, which can be modified during boot by kernel.
Although the above EFI memory map is all page-size aligned,
the one in /proc/iomem might be not so.
The best way to check the bug here is to see a full back trace
of makedumpfile to see where and how it resulted in
segmentation fault, just as Wang did.
If you feel awkward to get process core dump of makedumpfile
in the 2nd kernel, it's simpler to first get crash dump by
cp command to keep shape of /proc/vmcore and then use makedumpfile
to the generated crash dump. If makedumpfile crashes in the 2nd
kernel, it also crashes in the 1st kernel, since the crash dump
collected by cp command is the same as /proc/vmcore.
--
Thanks.
HATAYAMA, Daisuke
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