Messages in this thread | | | Date | Tue, 20 Apr 2010 16:33:07 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] hugetlbfs: Kill applications that use MAP_NORESERVE with SIGBUS instead of OOM-killer |
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On Tue, 20 Apr 2010 18:44:07 +0100 Mel Gorman <mel@csn.ul.ie> wrote:
> Ordinarily, application using hugetlbfs will create mappings with > reserves. For shared mappings, these pages are reserved before mmap() > returns success and for private mappings, the caller process is > guaranteed and a child process that cannot get the pages gets killed > with sigbus. > > An application that uses MAP_NORESERVE gets no reservations and mmap() > will always succeed at the risk the page will not be available at fault > time. This might be used for example on very large sparse mappings where the > developer is confident the necessary huge pages exist to satisfy all faults > even though the whole mapping cannot be backed by huge pages. Unfortunately, > if an allocation does fail, VM_FAULT_OOM is returned to the fault handler > which proceeds to trigger the OOM-killer. This is unhelpful. > > This patch alters hugetlbfs to kill a process that uses MAP_NORESERVE > where huge pages were not available with SIGBUS instead of triggering > the OOM killer. > > This patch if accepted should also be considered a -stable candidate.
Why? The changelog doesn't convey much seriousness?
> Signed-off-by: Mel Gorman <mel@csn.ul.ie> > --- > mm/hugetlb.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 6034dc9..af2d907 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1038,7 +1038,7 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, > page = alloc_buddy_huge_page(h, vma, addr); > if (!page) { > hugetlb_put_quota(inode->i_mapping, chg); > - return ERR_PTR(-VM_FAULT_OOM); > + return ERR_PTR(-VM_FAULT_SIGBUS); > } > } >
This affects hugetlb_cow() as well?
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