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Date: Fri, 04 Mar 2011 10:39:05 +0100 From: Jean-Philippe Menil <jean-philippe.menil@...v-nantes.fr> To: "Michael S. Tsirkin" <mst@...hat.com> CC: netdev@...r.kernel.org, kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org Subject: Re: Bug inkvm_set_irq Le 04/03/2011 10:35, Michael S. Tsirkin a écrit : > On Fri, Mar 04, 2011 at 10:22:03AM +0100, Jean-Philippe Menil wrote: >> Le 03/03/2011 16:55, Michael S. Tsirkin a écrit : >>> On Thu, Mar 03, 2011 at 04:26:11PM +0100, Jean-Philippe Menil wrote: >>>> Le 03/03/2011 15:47, Michael S. Tsirkin a écrit : >>>>> On Tue, Mar 01, 2011 at 03:39:12PM +0100, Jean-Philippe Menil wrote: >>>>>> so this time the bug is: >>>>>> >>>>>> [17882.612303] BUG: unable to handle kernel paging request at >>>>>> 0000000000002458 >>>>>> [17882.612342] IP: [<ffffffffa03898a0>] kvm_set_irq+0x30/0x140 [kvm] >>>>>> >>>>>> markup_oops give me this: >>>>>> >>>>>> root@...shire:~# cat bug-0103.txt | perl markup_oops.pl -m >>>>>> /lib/modules/2.6.37.2-dsiun-110105+/kernel/arch/x86/kvm/kvm.ko >>>>>> /boot/vmlinuz-2.6.37.2-dsiun-110105+ >>>>>> vmaoffset = 18446744072102621184 ffffffffa0389871: 48 89 e5 mov >>>>>> %rsp,%rbp >>>>>> ffffffffa0389874: 41 57 push %r15 >>>>>> ffffffffa0389876: 41 89 cf mov %ecx,%r15d | %r15 >>>>>> => 1 %ecx = 1 >>>>>> ffffffffa0389879: 41 56 push %r14 | %r14 >>>>>> => ffffffffa038aad0 >>>>>> ffffffffa038987b: 41 55 push %r13 >>>>>> ffffffffa038987d: 49 89 fd mov %rdi,%r13 | %edi >>>>>> = 0 %r13 => 0 >>>>>> ffffffffa0389880: 41 54 push %r12 | %r12 => 0 >>>>>> ffffffffa0389882: 53 push %rbx >>>>>> ffffffffa0389883: 89 d3 mov %edx,%ebx | %ebx => 1a >>>>>> ffffffffa0389885: 48 81 ec a8 00 00 00 sub $0xa8,%rsp >>>>>> ffffffffa038988c: 8b 15 00 00 00 00 mov 0x0(%rip),%edx >>>>>> # ffffffffa0389892<kvm_set_irq+0x22> >>>>>> ffffffffa0389892: 89 b5 3c ff ff ff mov %esi,-0xc4(%rbp) | >>>>>> %esi = 0 >>>>>> ffffffffa0389898: 85 d2 test %edx,%edx | %edx => 0 >>>>>> ffffffffa038989a: 0f 85 d5 00 00 00 jne ffffffffa0389975 >>>>>> <kvm_set_irq+0x105> >>>>>> *ffffffffa03898a0: 49 8b 85 58 24 00 00 mov 0x2458(%r13),%rax | >>>>>> %eax = 0 %r13 = 0<--- faulting instruction >>>>>> ffffffffa03898a7: 3b 98 28 01 00 00 cmp 0x128(%rax),%ebx >>>>>> ffffffffa03898ad: 73 61 jae ffffffffa0389910 >>>>>> <kvm_set_irq+0xa0> >>>>>> ffffffffa03898af: 89 db mov %ebx,%ebx >>>>>> ffffffffa03898b1: 48 8b 84 d8 30 01 00 mov 0x130(%rax,%rbx,8),%rax >>>>>> ffffffffa03898b8: 00 >>>>>> ffffffffa03898b9: 48 85 c0 test %rax,%rax >>>>>> ffffffffa03898bc: 74 52 je ffffffffa0389910 >>>>>> <kvm_set_irq+0xa0> >>>>>> ffffffffa03898be: 48 8d 95 40 ff ff ff lea -0xc0(%rbp),%rdx >>>>>> ffffffffa03898c5: 31 db xor %ebx,%ebx >>>>>> ffffffffa03898c7: 48 8b 08 mov (%rax),%rcx >>>>>> ffffffffa03898ca: 83 c3 01 add $0x1,%ebx >>>>>> ffffffffa03898cd: 0f 18 09 prefetcht0 (%rcx) >>>>>> ffffffffa03898d0: 48 8b 48 e0 mov -0x20(%rax),%rcx >>>>>> ffffffffa03898d4: 48 89 0a mov %rcx,(%rdx) >>>>>> ffffffffa03898d7: 48 8b 48 e8 mov -0x18(%rax),%rcx >>>>>> ffffffffa03898db: 48 89 4a 08 mov %rcx,0x8(%rdx) >>>>>> ffffffffa03898df: 48 8b 48 f0 mov -0x10(%rax),%rcx >>>>>> ffffffffa03898e3: 48 89 4a 10 mov %rcx,0x10(%rdx) >>>>>> ffffffffa03898e7: 48 8b 48 f8 mov -0x8(%rax),%rcx >>>>>> ffffffffa03898eb: 48 89 4a 18 mov %rcx,0x18(%rdx) >>>>>> >>>>>> wich correspond to offset 68a0 (from objdump): >>>>>> >>>>>> kvm_set_irq(): >>>>>> /usr/src/GIT/linux-2.6-stable/arch/x86/kvm/../../../virt/kvm/irq_comm.c:161 >>>>>> 68a0: 49 8b 85 58 24 00 00 mov 0x2458(%r13),%rax >>>>>> /usr/src/GIT/linux-2.6-stable/arch/x86/kvm/../../../virt/kvm/irq_comm.c:162 >>>>>> 68a7: 3b 98 28 01 00 00 cmp 0x128(%rax),%ebx >>>>>> >>>>>> root@...shire:~# addr2line -e >>>>>> /lib/modules/2.6.37.2-dsiun-110105+/kernel/arch/x86/kvm/kvm.ko >>>>>> 0x68a0 >>>>>> /usr/src/GIT/linux-2.6-stable/arch/x86/kvm/../../../virt/kvm/irq_comm.c:161 >>>>>> >>>>>> So here kvm->irq_routing is null. >>>>>> >>>>>> How can it be? >>>>>> >>>>>> Regards. >>>>> Not null, this seems to be invalid. >>>>> I suspect use after free where the kvm pointer is >>>>> pointing at some random memory. Use after free? >>>>> Could you please try enabling a slab debugger, >>>>> recompile and rerun the test? >>>>> >>>> Hi, >>>> >>>> I'm not sure to activate the right thing. >>>> Is that what you want? >>>> >>>> CONFIG_SLAB=y >>>> CONFIG_SLABINFO=y >>>> CONFIG_DEBUG_SLAB=y >>>> CONFIG_DEBUG_SLAB_LEAK=y >>>> >>>> Regards. >>> Yes, maybe disable SLAB_LEAK. >>> >>>> -- >>>> Jean-Philippe Menil - Pôle réseau Service IRTS >>>> DSI Université de Nantes >>>> jean-philippe.menil@...v-nantes.fr >>>> Tel : 02.53.48.49.27 - Fax : 02.53.48.49.09 >>> -- >>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>> the body of a message to majordomo@...r.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Hi, >> >> so this time, here is what markup_oops says: >> >> root@...shire:~# cat oops-0403.txt | perl markup_oops.pl -m >> /lib/modules/2.6.37.2.999-dsiun-110105+/kernel/arch/x86/kvm/kvm.ko >> /boot/vmlinuz-2.6.37.2.999-dsiun-110105+ >> vmaoffset = 18446744072102948864 ffffffffa03d9811: 48 89 e5 >> mov %rsp,%rbp >> ffffffffa03d9814: 41 57 push %r15 >> ffffffffa03d9816: 41 89 cf mov %ecx,%r15d | >> %r15 => 1 %ecx = 1 >> ffffffffa03d9819: 41 56 push %r14 | >> %r14 => ffffffffa03daa50 >> ffffffffa03d981b: 41 55 push %r13 >> ffffffffa03d981d: 49 89 fd mov %rdi,%r13 | >> %edi = 6b6b6b6b6b6b6b6b %r13 => 6b6b6b6b6b6b6b6b >> ffffffffa03d9820: 41 54 push %r12 | >> %r12 => 6b6b6b6b6b6b6b6b >> ffffffffa03d9822: 53 push %rbx >> ffffffffa03d9823: 89 d3 mov %edx,%ebx | >> %ebx => 6b6b6b6b >> ffffffffa03d9825: 48 81 ec a8 00 00 00 sub $0xa8,%rsp >> ffffffffa03d982c: 8b 15 00 00 00 00 mov 0x0(%rip),%edx >> # ffffffffa03d9832<kvm_set_irq+0x22> >> ffffffffa03d9832: 89 b5 3c ff ff ff mov >> %esi,-0xc4(%rbp) | %esi = 0 >> ffffffffa03d9838: 85 d2 test %edx,%edx | >> %edx => 0 >> ffffffffa03d983a: 0f 85 d5 00 00 00 jne >> ffffffffa03d9915<kvm_set_irq+0x105> >> *ffffffffa03d9840: 49 8b 85 58 24 00 00 mov >> 0x2458(%r13),%rax | %eax = 0 %r13 = 6b6b6b6b6b6b6b6b<--- faulting >> instruction >> ffffffffa03d9847: 3b 98 28 01 00 00 cmp 0x128(%rax),%ebx >> ffffffffa03d984d: 73 61 jae >> ffffffffa03d98b0<kvm_set_irq+0xa0> >> ffffffffa03d984f: 89 db mov %ebx,%ebx >> ffffffffa03d9851: 48 8b 84 d8 30 01 00 mov >> 0x130(%rax,%rbx,8),%rax >> ffffffffa03d9858: 00 >> ffffffffa03d9859: 48 85 c0 test %rax,%rax >> ffffffffa03d985c: 74 52 je >> ffffffffa03d98b0<kvm_set_irq+0xa0> >> ffffffffa03d985e: 48 8d 95 40 ff ff ff lea -0xc0(%rbp),%rdx >> ffffffffa03d9865: 31 db xor %ebx,%ebx >> ffffffffa03d9867: 48 8b 08 mov (%rax),%rcx >> ffffffffa03d986a: 83 c3 01 add $0x1,%ebx >> ffffffffa03d986d: 0f 18 09 prefetcht0 (%rcx) >> ffffffffa03d9870: 48 8b 48 e0 mov -0x20(%rax),%rcx >> ffffffffa03d9874: 48 89 0a mov %rcx,(%rdx) >> ffffffffa03d9877: 48 8b 48 e8 mov -0x18(%rax),%rcx >> ffffffffa03d987b: 48 89 4a 08 mov %rcx,0x8(%rdx) >> ffffffffa03d987f: 48 8b 48 f0 mov -0x10(%rax),%rcx >> ffffffffa03d9883: 48 89 4a 10 mov %rcx,0x10(%rdx) >> ffffffffa03d9887: 48 8b 48 f8 mov -0x8(%rax),%rcx >> ffffffffa03d988b: 48 89 4a 18 mov %rcx,0x18(%rdx) >> >> >> Is that you wanted, the "6b6b6b6b6b6b6b6b" ? >> >> Regards. > Yes, excellent. So now we can detect the problem by comparing > kvm with 6b6b6b6b6b6b6b6b, and print out stuff to understand where > this comes from. > I will prepare such a debugging patch. > > For that, could you please tell me which kernel version, exactly, are > you using? > > Yes, it's a 2.6.37.2 kernel. Thanks a lot. -- Jean-Philippe Menil - Pôle réseau Service IRTS DSI Université de Nantes jean-philippe.menil@...v-nantes.fr Tel : 02.53.48.49.27 - Fax : 02.53.48.49.09 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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