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SubjectRE: page fault in mem_cgroup_page_lruvec() due to memory hot-add
Date


> -----Original Message-----
> From: Michal Hocko [mailto:mstsxfx@gmail.com] On Behalf Of Michal Hocko
> Sent: Thursday, September 11, 2014 5:29 AM
> To: Dexuan Cui
> Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; Johannes Weiner;
> Hugh Dickins; KY Srinivasan
> Subject: Re: page fault in mem_cgroup_page_lruvec() due to memory hot-
> add
>
> On Thu 11-09-14 12:07:13, Dexuan Cui wrote:
> > Hi all,
> >
> > When I try to run Ubuntu 14.10 guest (the nightly build with the
> > kernel version 3.16.0-12-generic) on hyper-v, occasionally, I get the
> > below panic(see the end of the mail) suddenly.
> > (I suppose it's likely the upstream kernel has the issue too)
> >
> > When the panic happens, I'm running a memory stress program to test
> > the balloon driver drivers/hv/hv_balloon.c, which can hot-add memory
> > to the guest by invoking memory_add_physaddr_to_nid() and
> > add_memory(), if the feature "Dynamic Memory" is enabled.
> >
> > The issue here is: the memory hot-add seems successful, but
> > occasionally the page fault can happen and crash the whole guest.
> >
> > It looks the crash only happens to the guest in the SMP guest case. I
> > never get the crash when the guest is configured with 1 vCPU.
> >
> > Sometimes it's very difficult to reproduce the crash while sometimes
> > it's relatively easy.
> >
> > Can anybody please shed some light?
> >
> > Thanks!
> >
> > -- Dexuan
> >
> > [ 99.211382] BUG: unable to handle kernel paging request at
> 0000000000c0b608
> > [ 99.215308] IP: [<ffffffff811d2e9c>]
> mem_cgroup_page_lruvec+0x2c/0xa0
> > [ 99.215308] PGD 37544067 PUD 393c2067 PMD 0
> > [ 99.215308] Oops: 0000 [#1] SMP
> > [ 99.215308] Modules linked in: bnep rfcomm bluetooth 6lowpan_iphc
> joydev hid_generic crct10dif_pclmul crc32_pclmul ghash_clmulni_intel
> aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd
> hyperv_keyboard hv_balloon hid_hyperv hid serio_raw i2c_piix4 mac_hid
> parport_pc ppdev lp parport hv_netvsc hv_utils hv_storvsc psmouse
> hv_vmbus pata_acpi floppy
> > [ 99.215308] CPU: 3 PID: 1919 Comm: stressapptest Not tainted 3.16.0-12-
> generic #18-Ubuntu
> > [ 99.215308] Hardware name: Microsoft Corporation Virtual
> Machine/Virtual Machine, BIOS 090006 05/23/2012
> > [ 99.215308] task: ffff880034282880 ti: ffff8800415f8000 task.ti:
> ffff8800415f8000
> > [ 99.215308] RIP: 0010:[<ffffffff811d2e9c>] [<ffffffff811d2e9c>]
> mem_cgroup_page_lruvec+0x2c/0xa0
> > [ 99.215308] RSP: 0000:ffff8800415fbc58 EFLAGS: 00010006
> > [ 99.215308] RAX: 0000000000c0b600 RBX: ffff88003ffebf80 RCX:
> ffff88003ffea300
> > [ 99.215308] RDX: 02ffff00000d0001 RSI: ffff88003ffebf80 RDI:
> ffffea000302d800
> > [ 99.215308] RBP: ffff8800415fbc68 R08: 0000000000000008 R09:
> 0000000000000004
> > [ 99.215308] R10: 00000000ffffffff R11: ffff880033ffd400 R12:
> ffffea000302d800
> > [ 99.215308] R13: ffffea000302d800 R14: ffff88003b4703c0 R15:
> 0000000000000202
> > [ 99.215308] FS: 00007fb0075fa700(0000) GS:ffff88003b460000(0000)
> knlGS:0000000000000000
> > [ 99.215308] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> > [ 99.215308] CR2: 0000000000c0b608 CR3: 00000000389b4000 CR4:
> 00000000000006e0
> > [ 99.215308] Stack:
> > [ 99.215308] ffff88003ffebf80 0000000000000002 ffff8800415fbcc0
> ffffffff81178604
> > [ 99.215308] 0000000000000000 ffffffff81177bf0 0000000000000296
> ffff8800415fbc90
> > [ 99.215308] 0000000000000003 000000000004b5d8 00000000000200da
> ffff880036db6480
> > [ 99.215308] Call Trace:
> > [ 99.215308] [<ffffffff81178604>] pagevec_lru_move_fn+0xc4/0x130
> > [ 99.215308] [<ffffffff81177bf0>] ? __activate_page+0x1e0/0x1e0
> > [ 99.215308] [<ffffffff81178b7e>] lru_add_drain_cpu+0xce/0xe0
> > [ 99.215308] [<ffffffff81178c96>] lru_add_drain+0x16/0x20
> > [ 99.215308] [<ffffffff811aa2e6>] swapin_readahead+0x126/0x1a0
> > [ 99.215308] [<ffffffff81198c17>] handle_mm_fault+0xc87/0xf90
> > [ 99.215308] [<ffffffff8105ce42>] __do_page_fault+0x1c2/0x580
> > [ 99.215308] [<ffffffff810a9d18>] ? __enqueue_entity+0x78/0x80
> > [ 99.215308] [<ffffffff810ae8c4>] ? update_curr+0xf4/0x180
> > [ 99.215308] [<ffffffff810ab3f8>] ? pick_next_entity+0x88/0x180
> > [ 99.215308] [<ffffffff810b3b8e>] ? pick_next_task_fair+0x57e/0x8d0
> > [ 99.215308] [<ffffffff810a84e8>] ? sched_clock_cpu+0x88/0xb0
> > [ 99.215308] [<ffffffff8105d231>] do_page_fault+0x31/0x70
> > [ 99.215308] [<ffffffff81782908>] page_fault+0x28/0x30
> > [ 99.215308] Code: 66 66 66 90 8b 15 15 2a b5 00 55 48 8d 86 48 05 00 00 48
> 89 e5 41 54 53 85 d2 48 89 f3 75 56 49 89 fc e8 18 44 00 00 49 8b 14 24 <48> 8b
> 48 08 83 e2 20 75 1b 48 8b 10 83 e2 02 75 13 48 8b 15 54
> > [ 99.215308] RIP [<ffffffff811d2e9c>]
> mem_cgroup_page_lruvec+0x2c/0xa0
> > [ 99.215308] RSP <ffff8800415fbc58>
> > [ 99.215308] CR2: 0000000000c0b608
> > [ 99.215308] ---[ end trace 24db5f2378e898cb ]---
>
> This decodes to:
> All code
> ========
> 0: 66 66 66 90 data16 data16 xchg %ax,%ax
> 4: 8b 15 15 2a b5 00 mov 0xb52a15(%rip),%edx # 0xb52a1f
> a: 55 push %rbp
> b: 48 8d 86 48 05 00 00 lea 0x548(%rsi),%rax
> 12: 48 89 e5 mov %rsp,%rbp
> 15: 41 54 push %r12
> 17: 53 push %rbx
> 18: 85 d2 test %edx,%edx
> 1a: 48 89 f3 mov %rsi,%rbx
> 1d: 75 56 jne 0x75
> 1f: 49 89 fc mov %rdi,%r12
> 22: e8 18 44 00 00 callq 0x443f
> 27: 49 8b 14 24 mov (%r12),%rdx
> 2b:* 48 8b 48 08 mov 0x8(%rax),%rcx <-- trapping instruction
> 2f: 83 e2 20 and $0x20,%edx
> 32: 75 1b jne 0x4f
> 34: 48 8b 10 mov (%rax),%rdx
> 37: 83 e2 02 and $0x2,%edx
> 3a: 75 13 jne 0x4f
> 3c: 48 rex.W
> 3d: 8b .byte 0x8b
> 3e: 15 .byte 0x15
> 3f: 54 push %rsp
>
> and that matches to the following code:
> pc = lookup_page_cgroup(page);
> memcg = pc->mem_cgroup; <<< BANG
>
> So the lookup_page_cgroup returned a garbage (rax is supposed to be pc
> pointer but the value is definitely not a kernel pointer. It looks like an offset
> from zero base address). The page itself (rdi resp. r12 looks pretty normal to
> me). I would strongly suspect that the HyperV is doing something nasty
> when offlining the memory. Because there shouldn't be any page left behind
> when the node_data resp. mem_section (depending on the used memory
> model) is torn down.
>
> KY, any ideas?

I will take a look.

K. Y
> --
> Michal Hocko
> SUSE Labs


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