Bug#503821: More information regarding #503821 - Debian

This is a discussion on Bug#503821: More information regarding #503821 - Debian ; I've done some more tests. The problem seem to be related to swapping. I used this little test program: #include /* my amount of ram */ #define TESTSIZE 2048000 struct testchunk { char name[1048576]; }; main() { int *p; int ...

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Thread: Bug#503821: More information regarding #503821

  1. Bug#503821: More information regarding #503821

    I've done some more tests.

    The problem seem to be related to swapping.

    I used this little test program:

    #include

    /* my amount of ram */
    #define TESTSIZE 2048000

    struct testchunk {
    char name[1048576];
    };

    main()
    {
    int *p;
    int t;
    for (t=0;t p = (int *) malloc(sizeof(struct testchunk));
    }
    sleep(15);
    exit(0);
    }

    This basically allocates so much memory that my system starts to swap, and
    when the program exits (and free the memory) the kernel crashes. Every time.

    Normally my swap is set up swap-partiton->LVM->MD-raid1, but just to be sure
    I've used a swap-partition directly on a disk without LVM/MD involved with
    the same result.

    Now at least the error is easily reproduceable. Hopefully this can help
    to track the problem down.

    Best Regards,
    /LM






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  2. Bug#503821: Also in domU's

    Hello,

    On Wed, 29 Oct 2008, Lars Michael Jogback wrote:
    > I've done some more tests.
    >
    > The problem seem to be related to swapping.


    Thanks for figuring that out!

    I tested this with the following configurations where except for the
    kernel everthing else is from lenny (including the xen hypervisor
    which is 3.2). The kernels are the stock kernels from Debian.

    dom0 kernel domU kernel result
    2.6.18-6-xen-amd64 2.6.18-6-xen-amd64 no crash
    2.6.26-1-xen-amd64 2.6.26-1-xen-amd64 crash for domU and dom0
    2.6.18-6-xen-amd64 2.6.26-1-xen-amd64 crash for domU
    2.6.26-1-xen-amd64 2.6.18-6-xen-amd64 crash for dom0

    Moreover, in each case where there was a crash, disabling swap
    prevented the crash (the oom killer took over of course!).

    This clearly points to a problem which is in the way the kernel
    2.6.26-1-xen-amd64 deals with swap.

    This _is_ an RC bug. If people upgrade to lenny after it is released
    and have repeated crashes due to swapping problems they will not
    thank us.

    The report which downgraded this bug report from "grave" to
    "important" did not offer a reason.

    Regards,

    Kapil.
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