On Wed, Sep 02, 2009 at 11:02:14AM -0700, Luis R. Rodriguez wrote:

On Wed, Sep 2, 2009 at 10:48 AM, Bartlomiej
Zolnierkiewicz[off-list ref] wrote:

quoted

On Sunday 30 August 2009 14:37:42 Bartlomiej Zolnierkiewicz wrote:

quoted

On Friday 28 August 2009 05:42:31 Zhu Yi wrote:

quoted

Bartlomiej Zolnierkiewicz reported an atomic order-6 allocation failure
for ipw2200 firmware loading in kernel 2.6.30. High order allocation is

s/2.6.30/2.6.31-rc6/

The issue has always been there but it was some recent change that
explicitly triggered the allocation failures (after 2.6.31-rc1).

ipw2200 fix works fine but yesterday I got the following error while mounting
ext4 filesystem (mb_history is optional so the mount succeeded):

OK so the mount succeeded.

quoted

EXT4-fs (dm-2): barriers enabled
kjournald2 starting: pid 3137, dev dm-2:8, commit interval 5 seconds
EXT4-fs (dm-2): internal journal on dm-2:8
EXT4-fs (dm-2): delayed allocation enabled
EXT4-fs: file extents enabled
mount: page allocation failure. order:5, mode:0xc0d0
Pid: 3136, comm: mount Not tainted 2.6.31-rc8-00015-gadda766-dirty #78
Call Trace:
 [<c0394de3>] ? printk+0xf/0x14
 [<c016a693>] __alloc_pages_nodemask+0x400/0x442
 [<c016a71b>] __get_free_pages+0xf/0x32
 [<c01865cf>] __kmalloc+0x28/0xfa
 [<c023d96f>] ? __spin_lock_init+0x28/0x4d
 [<c01f529d>] ext4_mb_init+0x392/0x460
 [<c01e99d2>] ext4_fill_super+0x1b96/0x2012
 [<c0239bc8>] ? snprintf+0x15/0x17
 [<c01c0b26>] ? disk_name+0x24/0x69
 [<c018ba63>] get_sb_bdev+0xda/0x117
 [<c01e6711>] ext4_get_sb+0x13/0x15
 [<c01e7e3c>] ? ext4_fill_super+0x0/0x2012
 [<c018ad2d>] vfs_kern_mount+0x3b/0x76
 [<c018adad>] do_kern_mount+0x33/0xbd
 [<c019d0af>] do_mount+0x660/0x6b8
 [<c016a71b>] ? __get_free_pages+0xf/0x32
 [<c019d168>] sys_mount+0x61/0x99
 [<c0102908>] sysenter_do_call+0x12/0x36
Mem-Info:
DMA per-cpu:
CPU    0: hi:    0, btch:   1 usd:   0
Normal per-cpu:
CPU    0: hi:  186, btch:  31 usd:   0
Active_anon:25471 active_file:22802 inactive_anon:25812
 inactive_file:33619 unevictable:2 dirty:2452 writeback:135 unstable:0
 free:4346 slab:4308 mapped:26038 pagetables:912 bounce:0
DMA free:2060kB min:84kB low:104kB high:124kB active_anon:1660kB inactive_anon:1848kB active_file:144kB inactive_file:868kB unevictable:0kB present:15788kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 489 489
Normal free:15324kB min:2788kB low:3484kB high:4180kB active_anon:100224kB inactive_anon:101400kB active_file:91064kB inactive_file:133608kB unevictable:8kB present:501392kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0
DMA: 1*4kB 1*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 1*2048kB 0*4096kB = 2060kB
Normal: 1283*4kB 648*8kB 159*16kB 53*32kB 10*64kB 1*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15324kB
57947 total pagecache pages
878 pages in swap cache
Swap cache stats: add 920, delete 42, find 11/11
Free swap  = 1016436kB
Total swap = 1020116kB
131056 pages RAM
4233 pages reserved
90573 pages shared
77286 pages non-shared
EXT4-fs: mballoc enabled
EXT4-fs (dm-2): mounted filesystem with ordered data mode

Thus it seems like the original bug is still there and any ideas how to
debug the problem further are appreciated..

The complete dmesg and kernel config are here:

http://www.kernel.org/pub/linux/kernel/people/bart/ext4-paf.dmesg
http://www.kernel.org/pub/linux/kernel/people/bart/ext4-paf.config

This looks very similar to the kmemleak ext4 reports upon a mount. If
it is the same issue, which from the trace it seems it is, then this
is due to an extra kmalloc() allocation and this apparently will not
get fixed on 2.6.31 due to the closeness of the merge window and the
non-criticalness this issue has been deemed.

I suspect the more pressing concern is why is this kmalloc() resulting in
an order-5 allocation request? What size is the buffer being requested?
Was that expected?  What is the contents of /proc/slabinfo in case a buffer
that should have required order-1 or order-2 is using a higher order for
some reason.

A patch fix is part of the ext4-patchqueue
http://repo.or.cz/w/ext4-patch-queue.git

p.s. I'm will be offline until Tuesday so will not be initially very
responsive.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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