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    SubjectRe: [PATCH] mm: check zone->all_unreclaimable in all_unreclaimable()
    Date
    > On 03/08/2011 06:06 AM, KOSAKI Motohiro wrote:
    > >>>> Hmm.. Although it solves the problem, I think it's not a good idea that
    > >>>> depends on false alram and give up the retry.
    > >>>
    > >>> Any alternative proposals? We should get the livelock fixed if possible..
    > >>
    > >> I agree with Minchan and can't think this is a real fix....
    > >> Andrey, I'm now trying your fix and it seems your fix for oom-killer,
    > >> 'skip-zombie-process' works enough good for my environ.
    > >>
    > >> What is your enviroment ? number of cpus ? architecture ? size of memory ?
    > >
    > > me too. 'skip-zombie-process V1' work fine. and I didn't seen this patch
    > > improve oom situation.
    > >
    > > And, The test program is purely fork bomb. Our oom-killer is not silver
    > > bullet for fork bomb from very long time ago. That said, oom-killer send
    > > SIGKILL and start to kill the victim process. But, it doesn't prevent
    > > to be created new memory hogging tasks. Therefore we have no gurantee
    > > to win process exiting and creating race.
    >
    > I think a live-lock is a bug, even if it's provoked by fork bomds.
    >
    > And now I want say some words about zone->all_unreclaimable. I think
    > this flag is "conservative". It is set when situation is bad and it's
    > unset when situation get better. If we have a small number of
    > reclaimable pages, the situation is still bad. What do you mean, when
    > say that kernel is alive? If we have one reclaimable page, is the kernel
    > alive? Yes, it can work, it will generate many page faults and do
    > something, but anyone say that it is more dead than alive.
    >
    > Try to look at it from my point of view. The patch will be correct and
    > the kernel will be more alive.
    >
    > Excuse me, If I'm mistaken...

    Hi,

    Hmmm...
    If I could observed your patch, I did support your opinion. but I didn't. so, now I'm
    curious why we got the different conclusion. tommorow, I'll try to construct a test
    environment to reproduce your system.

    Unfortunatelly, zone->all_unreclamable is unreliable value while hibernation processing.
    Then I doubt current your patch is enough acceptable. but I'm not against to make alternative
    if we can observe the same phenomenon.

    At minimum, I also dislike kernel hang up issue.

    Thanks.



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