Re: [crash, -git] NULL pointer dereference, IP: [<c0190884>] page_cgroup_zoneinfo+0xf/0x1b

From: Balbir Singh
Date: Tue Oct 21 2008 - 06:43:27 EST


Ingo Molnar wrote:
> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>
>>> BUG: unable to handle kernel NULL pointer dereference at 00000000
>>> IP: [<c018faa4>] page_cgroup_zoneinfo+0xf/0x1b
> [...]
>>> bad: a9b6148: USB: Fix unused label warnings in drivers/usb/host/ehci-hcd.c
>>> good: c813b4e: Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/
>>>
>> yes, now chasing. and have found
>>
>> page_cgroup->page is NULL because of unknown reason.
>
> i've attempted to bisect it - but the most critical part of this series
> is not bisectable, the bootup hangs at this tree:
>
> 40b6a76: cpuset.c: remove extra variable
>
> It hangs in the mm/cgroups code at:
>
> [<c01895fe>] ? constant_test_bit+0xe/0x1b
> [<c01898a1>] lock_page_cgroup+0x13/0x25
> [<c0189e5f>] mem_cgroup_charge_common+0xfd/0x1bf
> [<c018a56f>] mem_cgroup_cache_charge+0x7c/0x8a
> [<c016bceb>] add_to_page_cache_locked+0x2f/0xc4
> [<c016bda3>] add_to_page_cache_lru+0x23/0x5e
> [<c016c3e9>] find_or_create_page+0x3f/0x62
> [<c01a4709>] __getblk+0xfa/0x1cc
> [<c01ff4fb>] jread+0x110/0x1ed
> [<c01ff6d4>] do_one_pass+0xfc/0x476
> [<c01408b0>] ? wake_bit_function+0x0/0x43
> [<c01ffac8>] journal_recover+0x7a/0x13d
> [<c0200d8e>] ? buffer_uptodate+0xc/0xe
> [<c0201bd9>] journal_load+0x42/0x76
> [<c01f810b>] ext3_fill_super+0xd9c/0x1491
>
> My bisection got this far:
>
> # good: [c813b4e1] Merge git://git.kernel.org/pub/scm/linux/kernel/gi
> # bad: [a9b6148d] USB: Fix unused label warnings in drivers/usb/host
> # bad: [656eb2cd] add CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS
> # good: [bdbf0ac7] Merge branch 'hwmon-for-linus' of git://jdelvare.p
> # good: [f7ea4a4b] Merge branch 'drm-next' of git://git.kernel.org/pu
> # good: [556adecb] vmscan: second chance replacement for anonymous pa
> # good: [28f74e71] hwmon/pc87360 separate alarm files: define some co
> # good: [46d01a22] ext3: fix ext3 block reservation early ENOSPC issu
> # good: [47c59803] devcgroup: remove spin_lock()
>
> The remaining bisection window of uncategorized commits is:
>
> nr of bisection commits: 14
> ----------------------------
> 656eb2c: add CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS
> 6409324: coredump: format_corename: don't append .%pid if multi-threaded
> b747c8c: make ptrace_untrace() static
> c459643: bitmask: remove bitmap_scnprintf_len()
> 30e8e13: cpuset: use seq_*mask_* to print masks
> 3eda201: seq_file: add seq_cpumask_list(), seq_nodemask_list()
> 85dd030: seq_file: don't call bitmap_scnprintf_len()
> 40b6a76: cpuset.c: remove extra variable
> 52d4b9a: memcg: allocate all page_cgroup at boot
> c05555b: memcg: atomic ops for page_cgroup->flags
> addb9ef: memcg: optimize per-cpu statistics
> 5b4e655: memcg: avoid accounting special pages
> b7abea9: memcg: make page->mapping NULL before uncharge
> 073e587: memcg: move charge swapin under lock
>
> i'll poke in the middle - maybe i'm lucky and can find a
> working/crashing tree to nudge the bisection back into life.

Hi, Ingo,

Li Zefan has reported this problem and Kamezawa is looking into it. I am unwell,
I hope to look into the problem when I feel better or at-least in the intervals
of time that I feel better.

--
Balbir
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