Messages in this thread | | | Date | Mon, 19 Sep 2005 20:56:26 +0200 | From | Petr Vandrovec <> | Subject | Re: 2.6.14-rc1-git-now still dying in mm/slab - this time line 1849 |
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Andrew Morton wrote: > Petr Vandrovec <vandrove@vc.cvut.cz> wrote: > >>Andrew Morton wrote: >> >>>Petr Vandrovec <vandrove@vc.cvut.cz> wrote: >>> >>> >>>>Andrew Morton wrote: >>>> >>>>>Petr Vandrovec <vandrove@vc.cvut.cz> wrote: >>>>> >>>>> >>>>>> so now once crashes on UP system were sorted out, I tried to >>>>>>put new kernel on my SMP host - and sorry to say, but it does not >>>>>>seem to work as advertised :-( >>>>> >>>>>.config (again), please. >>>> >>>>Any SMP with NUMA. One which I'm trying to debug now is attached. >>>>It is available at http://vana.vc.cvut.cz/config as well. >>> >>>I can get 2.6.14-rc1 to crash with your .config, but current -linus is OK. >> >>It still dies for me, with current git (tree 7513cdadc661cfe0bd1625145a4876e54df191ca, >>commit 6c0741fbdee5bd0f8ed13ac287c4ab18e8ba7d83). Config is available at >>http://platan.vc.cvut.cz/config-vana.txt. Box is dual opteron Tyan K8W, S2885. >> >>... >> >> ide0: BM-DMA at 0xffa0-0xffa7, BIOS settings: hda:DMA, hdb:pio >> ide1: BM-DMA at 0xffa8-0xffaf, BIOS settings: hdc:DMA, hdd:pio >>----------- [cut here ] --------- [please bite here ] --------- >>Kernel BUG at mm/slab.c:1849 >>invalid operand: 0000 [1] SMP >>CPU 0 >>Modules linked in: >>Pid: 8, comm: events/0 Not tainted 2.6.14-rc1-6c07 #1 >>RIP: 0010:[<ffffffff8016d316>] <ffffffff8016d316>{free_block+294} >>RSP: 0000:ffff81007ff21d88 EFLAGS: 00010002 >>RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000310 >>RDX: 0000000000000000 RSI: ffff81007ffddd10 RDI: ffff81007ffda080 >>RBP: ffff81007ffde000 R08: ffff81003ffa0d50 R09: 0000000000000000 >>R10: 00000000ffffffff R11: 0000000000000000 R12: ffff81007ffc9b50 >>R13: ffff81007ffde048 R14: ffff81007ffda080 R15: ffff81007ffda080 >>FS: 0000000000000000(0000) GS:ffffffff805f2800(0000) knlGS:0000000000000000 >>CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b >>CR2: 0000000000000000 CR3: 0000000000101000 CR4: 00000000000006e0 >>Process events/0 (pid: 8, threadinfo ffff81007ff20000, task ffff81003ff8c790) >>Stack: 0000000000000000 0000000000000000 0000000000000292 hda: _NEC DVD_RW ND-3500AG, ATAPI CD/DVD-ROM drive >>0000000200000000 >> ffff81007ffddd10 ffff81007ffddd10 ffff81007ffddce8 0000000000000002 >> 0000000000000000 ffff81007ffda080 >>Call Trace:<ffffffff8016e8b7>{drain_array_locked+167} <ffffffff8016e9f7>{cache_reap+231} >> <ffffffff80131e23>{__wake_up+67} <ffffffff8016e910>{cache_reap+0} >> <ffffffff8014930c>{worker_thread+476} <ffffffff80131d60>{default_wake_function+0} >> <ffffffff80131d60>{default_wake_function+0} <ffffffff80149130>{worker_thread+0} >> <ffffffff8014db82>{kthread+146} <ffffffff8010ec22>{child_rip+8} >> <ffffffff80149130>{worker_thread+0} <ffffffff8014daf0>{kthread+0} >> <ffffffff8010ec1a>{child_rip+0} >> >>Code: 0f 0b 68 9d 26 3d 80 c2 39 07 48 89 ee 4c 89 ff 4c 8d 75 30 >>RIP <ffffffff8016d316>{free_block+294} RSP <ffff81007ff21d88> >> ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 > > > Well. The CPU_UP_CANCELED locking in cpuup_callback() looks borked to me - > it takes cachep->nodelists[node]->list_lock and then calls > drain_alien_cache() which appears to take the same lock. But that's not > the problem here. > > The code in cache_reap() recalculates numa_node_id() multiple times, so if > the caller changes CPUs then this assertion will trigger. However it's > running under keventd here, which is pinned to a single CPU. Still, it > would be useful if you could try putting preempt_disable()s in > cache_reap(), or change cache_reap() to evaluate numa_node_id() just the > once, and cache that in a local variable. > > I wonder why numa_node_id() uses raw_smp_processor_id()? That's just > asking for preempt non-atomicity bugs.
I've thought that this is problem, but as far as I can tell while this is problem it does not happen here. Just free_block() finds that pointer it got from caller belongs to the slab that belongs to the CPU#1/node#1 while caller obtained lock on CPU#0/node#0 structures. Which suggests that drain_array_locked() was issued with node #0 while array_cache->entry it got contains blocks which belong to node #1. Which I cannot explain. Petr
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