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

From: Ingo Molnar
Date: Tue Oct 21 2008 - 06:39:49 EST

* 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://
> >
> 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://
# bad: [a9b6148d] USB: Fix unused label warnings in drivers/usb/host
# good: [bdbf0ac7] Merge branch 'hwmon-for-linus' of git://jdelvare.p
# good: [f7ea4a4b] Merge branch 'drm-next' of git://
# 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
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.


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