[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.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.


More information about the Bugme-new mailing list