On Tue, 16 Feb 2010 18:58:17 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote: > On Wed, 17 Feb 2010, KAMEZAWA Hiroyuki wrote: > > > > We want to lock all populated zones with ZONE_OOM_LOCKED to avoid > > > needlessly killing more than one task regardless of how many memcgs are > > > oom. > > > > > Current implentation archive what memcg want. Why remove and destroy memcg ? > > > > I've updated my patch to not take ZONE_OOM_LOCKED for any zones on memcg > oom. I'm hoping that you will add sysctl_panic_on_oom == 2 for this case > later, however. > I'll write panic_on_oom for memcg, later. > > What I mean is > > - What VM_FAULT_OOM means is not "memory is exhausted" but "something is exhausted". > > > > For example, when hugepages are all used, it may return VM_FAULT_OOM. > > Especially when nr_overcommit_hugepage == usage_of_hugepage, it returns VM_FAULT_OOM. > > > > The hugetlb case seems to be the only misuse of VM_FAULT_OOM where it > doesn't mean we simply don't have the memory to handle the page fault, > i.e. your earlier "memory is exhausted" definition. That was handled well > before calling out_of_memory() by simply killing current since we know it > is faulting hugetlb pages and its resource is limited. > > We could pass the vma to pagefault_out_of_memory() and simply kill current > if its killable and is_vm_hugetlb_page(vma). > No. hugepage is not only case. You may not read but we annoyed i915's driver bug recently and it was clearly misuse of VM_FAULT_OOM. Then, we got many reports of OOM killer in these months. (thanks to Kosaki about this.) quick glance around core codes... - HUGEPAGE at el. should return some VM_FAULT_NO_RESOUECE rather than VM_FAULT_OOM. - filemap.c's VM_FAULT_OOM shoudn't call page_fault_oom_kill because it has already called oom_killer if it can. - about relayfs, is VM_FAULT_OOM should be BUG_ON()... - filemap_xip.c return VM_FAULT_OOM....but it doesn't seem to be OOM.. just like VM_FAULT_NO_VALID_PAGE_FOUND. (But I'm not familiar with this area.) - fs/buffer.c 's VM_FAULT_OOM is returned oom-killer is called. - shmem.c's VM_FAULT_OOM is retuned oom-killer is called. i915's VM_FAULT_OOM is miterious but I can't find whether its real OOM or just shortage of is own resource. I think VM_FAULT_NO_RESOUCE should be added. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>