Re: Out of memory, but no OOM Killer? (2.6.9-ac11)

[Ralf Hildebrandt]

* Nick Piggin <nickpiggin@xxxxxxxxxxxx>:

> This could be the problem where fragmented memory causes atomic higher
> order allocations to fail, for which there is a fix in -mm, which should
> make its way into 2.6.11.

I see. rsync requested a big chunk of memory, but failed due to the
fragmentation of free memory? my "sar" output shows lots of free memory and
lots of unused swap:

03:55:01    kbmemfree kbmemused  %memused kbbuffers  kbcached kbswpfree kbswpused  %swpused  kbswpcad
04:55:01         2852    512048     99.45      2340    466792   2008084 0    0.00         0
05:05:02         2328    512572     99.55       500    467884   2008084 0    0.00         0
05:15:02         2008    512892     99.61       536    468664   2008084 0    0.00         0
05:25:01        31152    483748     93.95      1804    436728   2008084 0    0.00         0
05:35:01         4056    510844     99.21      5668    452856   2008084 0    0.00         0
05:45:01       129908    384992     74.77       836    305232   2008084 0    0.00         0
05:55:02         2376    512524     99.54       444    464200   2008084 0    0.00         0
06:05:02         1952    512948     99.62       608    465736   2008084 0    0.00         0
06:15:02         1576    513324     99.69       424    465580   2008084 0    0.00         0

for reference:
Nov 26 05:58:19 backup-in -- MARK --
Nov 26 06:02:04 backup-in kernel: rsync: page allocation failure. order:3, mode:0x20

> Also, the increased atomic memory reserves in current 2.6-bk should
> alleviate the problem.

2.4.27 doesn't seem to expose the problem either
 
> As a temporary workaround, you can increase /proc/sys/vm/min_free_kbytes

# cat /proc/sys/vm/min_free_kbytes
724

I increased that to 7240 now.

> BTW. what does `free` say when the allocation failures are happening?

see sar output above.

-- 
Ralf Hildebrandt (i.A. des IT-Zentrum)          Ralf.Hildebrandt@xxxxxxxxxx
Charite - Universitätsmedizin Berlin            Tel.  +49 (0)30-450 570-155
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