On Mon 10-12-12 11:18:17, azurIt wrote:

quoted

Hmm, this is _really_ surprising. The latest patch didn't add any new
logging actually. It just enahanced messages which were already printed
out previously + changed few functions to be not inlined so they show up
in the traces. So the only explanation is that the workload has changed
or the patches got misapplied.

This time i installed 3.2.35, maybe some changes between .34 and .35
did this? Should i try .34?

I would try to limit changes to minimum. So the original kernel you were
using + the first patch to prevent OOM from the write path + 2 debugging
patches.
 

quoted

quoted

Dec 10 02:03:29 server01 kernel: [  220.366486] grsec: From 141.105.120.152: bruteforce prevention initiated for the next 30 minutes or until service restarted, stalling each fork 30 seconds.  Please investigate the crash report for /usr/lib/apache2/mpm-itk/apache2[apache2:3586] uid/euid:1258/1258 gid/egid:100/100, parent /usr/lib/apache2/mpm-itk/apache2[apache2:2142] uid/euid:0/0 gid/egid:0/0

This explains why you have seen your machine hung. I am not familiar
with grsec but stalling each fork 30s sounds really bad.

Btw, i never ever saw such a message from grsecurity yet. Will write to grsec mailing list about explanation.

quoted

Anyway this will not help me much. Do you happen to still have any of
those logged traces from the last run?

Unfortunately not, it didn't log anything and tons of messages were
printed only to console (i was logged via IP-KVM). It looked that
printing is infinite, i rebooted it after few minutes.

But was it at least related to the debugging from the patch or it was
rather a totally unrelated thing?

quoted

Apart from that. If my current understanding is correct then this is
related to transparent huge pages (and leaking charge to the page fault
handler). Do you see the same problem if you disable THP before you
start your workload? (echo never > /sys/kernel/mm/transparent_hugepage/enabled)

# cat /sys/kernel/mm/transparent_hugepage/enabled
cat: /sys/kernel/mm/transparent_hugepage/enabled: No such file or directory

Weee. Then it cannot be related to THP at all. Which makes this even
bigger mystery.
We really need to find out who is leaking that charge.

-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>