[Bugme-new] [Bug 40402] New: Memory being cached and not released causing out_of_memory issue or high swap usage when memory is not used up
bugzilla-daemon at bugzilla.kernel.org
bugzilla-daemon at bugzilla.kernel.org
Mon Aug 1 03:04:08 PDT 2011
https://bugzilla.kernel.org/show_bug.cgi?id=40402
Summary: Memory being cached and not released causing
out_of_memory issue or high swap usage when memory is
not used up
Product: Memory Management
Version: 2.5
Kernel Version: 2.6.38 2.6.39
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: blocking
Priority: P1
Component: Other
AssignedTo: akpm at linux-foundation.org
ReportedBy: ultimatebusta at gmail.com
Regression: No
Hi,
This is my first bug report to kernel.org, so I apologize if I failed to do
something.
I've been having issues with memory for the past month or so (Physical memory
installed is 4GB). It started out with random freezes, usually occurring a
couple hours after initial boot. Then the system will freeze completely. Later,
through logs, I found this:
http://pastebin.com/raw.php?i=KAc87YVa
This shows me that I'm out of memory, but I'm far from that, as I hardly ever
use more than 1.5GB of memory.
Later I realized that this was caused by swap being full, and no memory could
be allocated, as demonstrated by this screencap:
http://i.stack.imgur.com/Wuvf1.png
Finally I noticed a trend from free -m:
1. Boot up computer, the "cached" part is low and the "free" part is high
2. Gradually, the "cached" part increases and the "free" part decreases.
3. The "free" part drops to around 100MB
4. Swap begins accumulating.
I've done some homework, although I do not completely understand what "cached"
actually does, I know that it's suppose to be automatically released by the
kernel if a program requested more memory in "free" (at least this is how I
understand it).
Demonstrated by this free -m output:
total used free shared buffers cached
Mem: 3760 3653 107 0 4 2638
-/+ buffers/cache: 1010 2750
Swap: 3890 2643 1247
Currently I have to restart every 8 hours in order to avoid a total system
freeze after swap goes full. (can't move mouse, lasts forever (40 minutes and
got impatient.. hard reset))
My current system is Ubuntu 11.04 64bit with the kernel compiled with
kernelcheck. uname -r: 2.6.39.3-candela
Also, I'm apparently not the only person experiencing this issue, someone from
the #ubuntu-cn chatroom is also having this issue with Ubuntu 11.04 32bit with
a generic kernel (uname -r: 2.6.38-11-generic) (2GB RAM) (5 hours per restart)
There's also maybe another person experiencing the same issue on Fedora, yet
his case has yet to be confirmed. (16GB ram and recently upgraded to the 2.6.40
kernel, yet to confirm with both the old and the new kernel as it takes him 52
hours in order for cached to "eat" all the ram)
If you need any additional information, I'll be happy to provide them to you,
and you can also find us on #ubuntu-cn (Find Pwnna)
Thank you very much.
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