From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 6533D6B01F5 for ; Tue, 20 Apr 2010 19:33:57 -0400 (EDT) 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 Message-Id: <20100420163307.785a6cb2.akpm@linux-foundation.org> In-Reply-To: <20100420174407.GA30306@csn.ul.ie> References: <20100420174407.GA30306@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Lee Schermerhorn , David Rientjes , Andi Kleen , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, 20 Apr 2010 18:44:07 +0100 Mel Gorman 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 > --- > 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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org