Re: [Xen-devel] VM Crash when Xen open page sharing

[Jui-Hao Chiang <juihaochiang@xxxxxxxxx>]

Hi, Pengfei:

Could you turn on the #define MEM_SHARING_AUDIT  0 in mem_sharing.c?
It seems you reach the last bug found by Xiaoyun, which crashes at the
exactly same position as yours. (you can try to search the archive).

At the last test, we found there are pages missing from the hash list
of mem_sharing, which is taken by other unknown components in Xen.
And we wonder the reason is the p2m type can't protect well the
mem_sharing pages, so the page is used by someone else.

Bests,
Jui-Hao


On Sun, Apr 10, 2011 at 8:53 PM, pengfei zhang <zpfalpc23@xxxxxxxxxxx> wrote:
> Hi all,
> Recently, I try to fix the bugs of xen memory sharing and now it nearly
> works. I boot 28 VM(RHEL5.4, 4 VCPUS and 512M memory) in every 20s, and
> reboot each one in 10 mins, and find that it saves 4G for Xen when I use "xm
> info".
>
> But sometimes in my test, it encounter VM crashes, after viewing  the kernel
> stack backtrace of VM, I find it crash on the same point!
> Here come the kernel stack backtrace:
>
> crash> bt -l
> PID: 1682   TASK: ffff81001cc727e0  CPU: 1   COMMAND: "setfont"
>  #0 [ffff810018f5f900] xen_panic_event at ffffffff88001d28
>  #1 [ffff810018f5f920] notifier_call_chain at ffffffff80066eaa
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/kernel/sys.c:
> 146
>  #2 [ffff810018f5f940] panic at ffffffff8009094a
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/kernel/panic.c:
> 101
>  #3 [ffff810018f5fa30] oops_end at ffffffff80064fca
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/arch/x86_64/kernel/traps.c:
> 539
>  #4 [ffff810018f5fa48] zone_statistics at ffffffff800caabe
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/mm/vmstat.c: 372
>  #5 [ffff810018f5fac8] zone_statistics at ffffffff800caabe
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/mm/vmstat.c: 372
>  #6 [ffff810018f5fb30] error_exit at ffffffff8005dde9
>    include/linux/bitops.h: 42
>    [exception RIP: vgacon_do_font_op+363]
>    RIP: ffffffff800515e5  RSP: ffff810018f5fbe8  RFLAGS: 00010203
>    RAX: 0000000000000000  RBX: ffffffff804b3740  RCX: ffff8100000a056d
>    RDX: 000000000000056e  RSI: ffff81001c458000  RDI: ffffffff803244c4
>    RBP: ffff81001c458000   R8: d0d6999996000000   R9: 0000009090b0b0ff
>    R10: 0000000000000000  R11: 0000000000000000  R12: 0000000000000004
>    R13: 0000000000000001  R14: 0000000000000001  R15: 000000000000000e
>    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
>  #7 [ffff810018f5fbe0] vgacon_do_font_op at ffffffff800514e5
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/video/console/vgacon.c:
> 1078
>  #8 [ffff810018f5fc20] vgacon_font_set at ffffffff8016bec5
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/video/console/vgacon.c:
> 1238
>  #9 [ffff810018f5fc60] con_font_op at ffffffff801aa86b
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/char/vt.c:
> 3645
> #10 [ffff810018f5fcd0] vt_ioctl at ffffffff801a5af4
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/char/vt_ioctl.c:
> 965
> #11 [ffff810018f5fd70] tty_ioctl at ffffffff80038a2c
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/char/tty_io.c:
> 3340
> #12 [ffff810018f5feb0] do_ioctl at ffffffff800420d9
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/fs/ioctl.c: 39
> #13 [ffff810018f5fed0] vfs_ioctl at ffffffff800302ce
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/fs/ioctl.c: 500
> #14 [ffff810018f5ff40] sys_ioctl at ffffffff8004c766
>    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/fs/ioctl.c: 520
> #15 [ffff810018f5ff80] system_call at ffffffff8005d116
>
> /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/arch/x86_64/kernel/entry.S
>    RIP: 00000039294cc557  RSP: 00007fff63bcf668  RFLAGS: 00010206
>    RAX: 0000000000000010  RBX: ffffffff8005d116  RCX: 0000000000000000
>    RDX: 00007fff63bcf600  RSI: 0000000000004b72  RDI: 0000000000000003
>    RBP: 000000001b7d8ab0   R8: 0000000000000010   R9: 0000000000800000
>    R10: 0000000000000000  R11: 0000000000000246  R12: 0000000000000010
>    R13: 0000000000000200  R14: 0000000000000008  R15: 0000000000000008
>    ORIG_RAX: 0000000000000010  CS: 0033  SS: 002b
>
> the VM redhat kernel is from
> http://rhkernel.org/kernelrpmsRHEL5/kernel-2.6.18-164.el5.src.rpm
>
> Can some one help me with this problem? Thx!
>                       --pengfei zhang
>
> --
> View this message in context: 
> http://xen.1045712.n5.nabble.com/VM-Crash-when-Xen-open-page-sharing-tp4294225p4294225.html
> Sent from the Xen - Dev mailing list archive at Nabble.com.
>
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