From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by kanga.kvack.org (Postfix) with ESMTP id E76E16B0036 for ; Mon, 28 Oct 2013 06:00:57 -0400 (EDT) Received: by mail-pa0-f49.google.com with SMTP id lj1so6911136pab.36 for ; Mon, 28 Oct 2013 03:00:57 -0700 (PDT) Received: from psmtp.com ([74.125.245.141]) by mx.google.com with SMTP id kk1si11549606pbc.34.2013.10.28.03.00.56 for ; Mon, 28 Oct 2013 03:00:56 -0700 (PDT) Received: by mail-pb0-f42.google.com with SMTP id jt11so6224658pbb.15 for ; Mon, 28 Oct 2013 03:00:55 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20131025161555.GA4398@plex.lan> <20131026033936.GA14971@cmpxchg.org> <526BB98B.4070207@alibaba-inc.com> Date: Mon, 28 Oct 2013 18:00:54 +0800 Message-ID: Subject: Re: RIP: mem_cgroup_move_account+0xf4/0x290 From: Sha Zhengju Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Greg Thelen Cc: Andrew Morton , fbl@redhat.com, Johannes Weiner , LKML , "linux-mm@kvack.org" On Sat, Oct 26, 2013 at 11:41 PM, Greg Thelen wrote: > On Sat, Oct 26 2013, wrote: > >> On 10/26/2013 11:39 AM, Johannes Weiner wrote: >>> On Fri, Oct 25, 2013 at 02:15:55PM -0200, Flavio Leitner wrote: >>>> While playing with guests and net-next kernel, I've triggered >>>> this with some frequency. Even Fedora 19 kernel reproduces. >>>> >>>> It it a known issue? >>>> >>>> Thanks, >>>> fbl >>>> >>>> [ 6790.349763] kvm: zapping shadow pages for mmio generation wraparound >>>> [ 6792.283879] kvm: zapping shadow pages for mmio generation wraparound >>>> [ 7535.654438] perf samples too long (2719 > 2500), lowering kernel.perf_event_max_sample_rate to 50000 >>>> [ 7535.665948] INFO: NMI handler (perf_event_nmi_handler) took too long to run: 11.560 msecs >>>> [ 7691.048392] virbr0: port 1(vnet0) entered disabled state >>>> [ 7691.056281] device vnet0 left promiscuous mode >>>> [ 7691.061674] virbr0: port 1(vnet0) entered disabled state >>>> [ 7691.163363] BUG: unable to handle kernel paging request at 000060fbc0002a20 >>>> [ 7691.171145] IP: [] mem_cgroup_move_account+0xf4/0x290 >>>> [ 7691.178574] PGD 0 >>>> [ 7691.181042] Oops: 0000 [#1] SMP >>>> [ 7691.184761] Modules linked in: vhost_net vhost macvtap macvlan tun veth >>>> openvswitch xt_CHECKSUM nf_conntrack_netbios_ns nf_conntrack_broadcast >>>> ipt_MASQUERADE ip6t_REJECT xt_conntrack ebtable_nat ebtable_broute bridge stp >>>> llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 >>>> nf_nat_ipv6 vxlan ip_tunnel gre libcrc32c ip6table_mangle ip6table_security >>>> ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 >>>> nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle >>>> iptable_security iptable_raw coretemp kvm_intel snd_hda_codec_realtek >>>> snd_hda_intel nfsd snd_hda_codec kvm auth_rpcgss nfs_acl snd_hwdep lockd >>>> snd_seq snd_seq_device snd_pcm e1000e snd_page_alloc sunrpc snd_timer >>>> crc32c_intel i7core_edac bnx2 shpchp ptp snd iTCO_wdt joydev pps_core >>>> iTCO_vendor_support pcspkr soundcore microcode serio_raw lpc_ich edac_core >>>> mfd_core i2c_i801 acpi_cpufreq hid_logitech_dj nouveau ata_generic pata_acpi >>>> video i2c_algo_bit drm_kms_helper ttm drm mxm_wmi i2c_core pata_marvell wmi >>>> [last unloaded: openvswitch] >>>> [ 7691.285989] CPU: 1 PID: 14 Comm: kworker/1:0 Tainted: G I 3.12.0-rc6-01188-gb45bd46 #1 >>>> [ 7691.295779] Hardware name: /DX58SO, BIOS SOX5810J.86A.5599.2012.0529.2218 05/29/2012 >>>> [ 7691.306066] Workqueue: events css_killed_work_fn >>>> [ 7691.311303] task: ffff880429555dc0 ti: ffff88042957a000 task.ti: ffff88042957a000 >>>> [ 7691.319673] RIP: 0010:[] [] mem_cgroup_move_account+0xf4/0x290 >>>> [ 7691.329728] RSP: 0018:ffff88042957bcc8 EFLAGS: 00010002 >>>> [ 7691.335747] RAX: 0000000000000246 RBX: ffff88042b17bc30 RCX: 0000000000000004 >>>> [ 7691.343720] RDX: ffff880424cd6000 RSI: 000060fbc0002a08 RDI: ffff880424cd622c >>>> [ 7691.351735] RBP: ffff88042957bd20 R08: ffff880424cd4000 R09: 0000000000000001 >>>> [ 7691.359751] R10: 0000000000000001 R11: 0000000000000001 R12: ffffea00103ef0c0 >>>> [ 7691.367745] R13: ffff880424cd6000 R14: 0000000000000000 R15: ffff880424cd622c >>>> [ 7691.375738] FS: 0000000000000000(0000) GS:ffff88043fc20000(0000) knlGS:0000000000000000 >>>> [ 7691.384755] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b >>>> [ 7691.391238] CR2: 000060fbc0002a20 CR3: 0000000001c0c000 CR4: 00000000000027e0 >>>> [ 7691.399235] Stack: >>>> [ 7691.401672] ffff88042957bce8 ffff88042957bce8 ffffffff81312b6d ffff880424cd4000 >>>> [ 7691.409968] ffff880400000001 ffff880424cd6000 ffffea00103ef0c0 ffff880424cd0430 >>>> [ 7691.418264] ffff88042b17bc30 ffffea00103ef0e0 ffff880424cd6000 ffff88042957bda8 >>>> [ 7691.426578] Call Trace: >>>> [ 7691.429513] [] ? list_del+0xd/0x30 >>>> [ 7691.435250] [] mem_cgroup_reparent_charges+0x247/0x460 >>>> [ 7691.442874] [] mem_cgroup_css_offline+0xaf/0x1b0 >>>> [ 7691.449942] [] offline_css+0x27/0x50 >>>> [ 7691.455874] [] css_killed_work_fn+0x2d/0xa0 >>>> [ 7691.462466] [] process_one_work+0x175/0x430 >>>> [ 7691.469041] [] worker_thread+0x11b/0x3a0 >>>> [ 7691.475345] [] ? rescuer_thread+0x340/0x340 >>>> [ 7691.481919] [] kthread+0xc0/0xd0 >>>> [ 7691.487478] [] ? insert_kthread_work+0x40/0x40 >>>> [ 7691.494352] [] ret_from_fork+0x7c/0xb0 >>>> [ 7691.500464] [] ? insert_kthread_work+0x40/0x40 >>>> [ 7691.507335] Code: 85 f6 48 8b 55 d0 44 8b 4d c8 4c 8b 45 c0 0f 85 b3 00 00 >>>> 00 41 8b 4c 24 18 85 c9 0f 88 a6 00 00 00 48 8b b2 30 02 00 00 45 89 ca <4c> >>>> 39 56 18 0f 8c 36 01 00 00 44 89 c9 f7 d9 89 cf 65 48 01 7e >>> This is >>> >>> All code >>> ======== >>> 0: 85 f6 test %esi,%esi >>> 2: 48 8b 55 d0 mov -0x30(%rbp),%rdx >>> 6: 44 8b 4d c8 mov -0x38(%rbp),%r9d >>> a: 4c 8b 45 c0 mov -0x40(%rbp),%r8 >>> e: 0f 85 b3 00 00 00 jne 0xc7 >>> 14: 41 8b 4c 24 18 mov 0x18(%r12),%ecx >>> 19: 85 c9 test %ecx,%ecx >>> 1b: 0f 88 a6 00 00 00 js 0xc7 >>> 21: 48 8b b2 30 02 00 00 mov 0x230(%rdx),%rsi >>> 28: 45 89 ca mov %r9d,%r10d >>> 2b:* 4c 39 56 18 cmp %r10,0x18(%rsi) <-- trapping instruction >>> 2f: 0f 8c 36 01 00 00 jl 0x16b >>> 35: 44 89 c9 mov %r9d,%ecx >>> 38: f7 d9 neg %ecx >>> 3a: 89 cf mov %ecx,%edi >>> 3c: 65 gs >>> 3d: 48 rex.W >>> 3e: 01 .byte 0x1 >>> 3f: 7e .byte 0x7e >>> >>> which corresponds to >>> >>> WARN_ON_ONCE(from->stat->count[idx] < nr_pages); >>> >>> Humm. from->stat is a percpu pointer... This patch should fix it: >>> >>> --- >>> From 4e9fe9d7e8502eab1c8bb4761de838f61cd4a8e0 Mon Sep 17 00:00:00 2001 >>> From: Johannes Weiner >>> Date: Fri, 25 Oct 2013 23:23:31 -0400 >>> Subject: [patch] mm: memcg: fix percpu variable access crash >>> >>> 3ea67d06e467 ("memcg: add per cgroup writeback pages accounting") >>> added a WARN_ON_ONCE() to sanity check the page statistics counter >>> when moving charges. Unfortunately, it dereferences the percpu >>> counter directly, which may result in a crash like this: >>> >>> [ 7691.163363] BUG: unable to handle kernel paging request at 000060fbc0002a20 >>> [ 7691.171145] IP: [] mem_cgroup_move_account+0xf4/0x290 >>> [ 7691.178574] PGD 0 >>> [ 7691.181042] Oops: 0000 [#1] SMP >>> [...] >>> [ 7691.285989] CPU: 1 PID: 14 Comm: kworker/1:0 Tainted: G I 3.12.0-rc6-01188-gb45bd46 #1 >>> [ 7691.295779] Hardware name: /DX58SO, BIOS SOX5810J.86A.5599.2012.0529.2218 05/29/2012 >>> [ 7691.306066] Workqueue: events css_killed_work_fn >>> [ 7691.311303] task: ffff880429555dc0 ti: ffff88042957a000 task.ti: ffff88042957a000 >>> [ 7691.319673] RIP: 0010:[] [] mem_cgroup_move_account+0xf4/0x290 >>> [ 7691.329728] RSP: 0018:ffff88042957bcc8 EFLAGS: 00010002 >>> [ 7691.335747] RAX: 0000000000000246 RBX: ffff88042b17bc30 RCX: 0000000000000004 >>> [ 7691.343720] RDX: ffff880424cd6000 RSI: 000060fbc0002a08 RDI: ffff880424cd622c >>> [ 7691.351735] RBP: ffff88042957bd20 R08: ffff880424cd4000 R09: 0000000000000001 >>> [ 7691.359751] R10: 0000000000000001 R11: 0000000000000001 R12: ffffea00103ef0c0 >>> [ 7691.367745] R13: ffff880424cd6000 R14: 0000000000000000 R15: ffff880424cd622c >>> [ 7691.375738] FS: 0000000000000000(0000) GS:ffff88043fc20000(0000) knlGS:0000000000000000 >>> [ 7691.384755] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b >>> [ 7691.391238] CR2: 000060fbc0002a20 CR3: 0000000001c0c000 CR4: 00000000000027e0 >>> [ 7691.399235] Stack: >>> [ 7691.401672] ffff88042957bce8 ffff88042957bce8 ffffffff81312b6d ffff880424cd4000 >>> [ 7691.409968] ffff880400000001 ffff880424cd6000 ffffea00103ef0c0 ffff880424cd0430 >>> [ 7691.418264] ffff88042b17bc30 ffffea00103ef0e0 ffff880424cd6000 ffff88042957bda8 >>> [ 7691.426578] Call Trace: >>> [ 7691.429513] [] ? list_del+0xd/0x30 >>> [ 7691.435250] [] mem_cgroup_reparent_charges+0x247/0x460 >>> [ 7691.442874] [] mem_cgroup_css_offline+0xaf/0x1b0 >>> [ 7691.449942] [] offline_css+0x27/0x50 >>> [ 7691.455874] [] css_killed_work_fn+0x2d/0xa0 >>> [ 7691.462466] [] process_one_work+0x175/0x430 >>> [ 7691.469041] [] worker_thread+0x11b/0x3a0 >>> [ 7691.475345] [] ? rescuer_thread+0x340/0x340 >>> [ 7691.481919] [] kthread+0xc0/0xd0 >>> [ 7691.487478] [] ? insert_kthread_work+0x40/0x40 >>> [ 7691.494352] [] ret_from_fork+0x7c/0xb0 >>> [ 7691.500464] [] ? insert_kthread_work+0x40/0x40 >>> [ 7691.507335] Code: 85 f6 48 8b 55 d0 44 8b 4d c8 4c 8b 45 c0 0f 85 b3 00 00 00 41 8b 4c 24 18 >>> 85 c9 0f 88 a6 00 00 00 48 8b b2 30 02 00 00 45 89 ca <4c> 39 56 18 0f 8c 36 01 00 00 44 89 c9 >>> f7 d9 89 cf 65 48 01 7e >>> [ 7691.528638] RIP [] mem_cgroup_move_account+0xf4/0x290 >>> >>> Add the required __this_cpu_read(). >> >> Sorry for my mistake and thanks for the fix up, it looks good to me. >> >> Reviewed-by: Sha Zhengju >> >> >> Thanks, >> Sha >>> >>> Signed-off-by: Johannes Weiner >>> --- >>> mm/memcontrol.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>> index 4097a78..a4864b6 100644 >>> --- a/mm/memcontrol.c >>> +++ b/mm/memcontrol.c >>> @@ -3773,7 +3773,7 @@ void mem_cgroup_move_account_page_stat(struct mem_cgroup *from, >>> { >>> /* Update stat data for mem_cgroup */ >>> preempt_disable(); >>> - WARN_ON_ONCE(from->stat->count[idx] < nr_pages); >>> + WARN_ON_ONCE(__this_cpu_read(from->stat->count[idx]) < nr_pages); >>> __this_cpu_add(from->stat->count[idx], -nr_pages); >>> __this_cpu_add(to->stat->count[idx], nr_pages); >>> preempt_enable(); >> >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: email@kvack.org > > I was just polishing up this following patch which I think is better > because it should avoid spurious warnings. > > ---8<--- > > From c1f43ef0f4cc42fb2ecaeaca71bd247365e3521e Mon Sep 17 00:00:00 2001 > From: Greg Thelen > Date: Fri, 25 Oct 2013 21:59:57 -0700 > Subject: [PATCH] memcg: remove incorrect underflow check > > When a memcg is deleted mem_cgroup_reparent_charges() moves charged > memory to the parent memcg. As of v3.11-9444-g3ea67d0 "memcg: add per > cgroup writeback pages accounting" there's bad pointer read. The goal > was to check for counter underflow. The counter is a per cpu counter > and there are two problems with the code: > (1) per cpu access function isn't used, instead a naked pointer is > used which easily causes panic. > (2) the check doesn't sum all cpus > > Test: > $ cd /sys/fs/cgroup/memory > $ mkdir x > $ echo 3 > /proc/sys/vm/drop_caches > $ (echo $BASHPID >> x/tasks && exec cat) & > [1] 7154 > $ grep ^mapped x/memory.stat > mapped_file 53248 > $ echo 7154 > tasks > $ rmdir x > > > The fix is to remove the check. It's currently dangerous and isn't > worth fixing it to use something expensive, such as > percpu_counter_sum(), for each reparented page. __this_cpu_read() > isn't enough to fix this because there's no guarantees of the current > cpus count. The only guarantees is that the sum of all per-cpu > counter is >= nr_pages. Yes... you're right. We should check the total stats of 'from' memcg rather than the per cpu stat. I vote to remove the check completely. Thanks for fixing this. > > Signed-off-by: Greg Thelen Reviewed-by: Sha Zhengju Thanks. > --- > mm/memcontrol.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 34d3ca9..aa8185c 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3773,7 +3773,6 @@ void mem_cgroup_move_account_page_stat(struct mem_cgroup *from, > { > /* Update stat data for mem_cgroup */ > preempt_disable(); > - WARN_ON_ONCE(from->stat->count[idx] < nr_pages); > __this_cpu_add(from->stat->count[idx], -nr_pages); > __this_cpu_add(to->stat->count[idx], nr_pages); > preempt_enable(); > -- > 1.8.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Thanks, Sha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org