From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id C32326B004D for ; Tue, 10 Nov 2009 17:06:51 -0500 (EST) Date: Tue, 10 Nov 2009 22:06:49 +0000 (GMT) From: Hugh Dickins Subject: [PATCH 6/6] mm: sigbus instead of abusing oom In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Izik Eidus , Andrea Arcangeli , KAMEZAWA Hiroyuki , Minchan Kim , Andi Kleen , Wu Fengguang , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: When do_nonlinear_fault() realizes that the page table must have been corrupted for it to have been called, it does print_bad_pte() and returns ... VM_FAULT_OOM, which is hard to understand. It made some sense when I did it for 2.6.15, when do_page_fault() just killed the current process; but nowadays it lets the OOM killer decide who to kill - so page table corruption in one process would be liable to kill another. Change it to return VM_FAULT_SIGBUS instead: that doesn't guarantee that the process will be killed, but is good enough for such a rare abnormality, accompanied as it is by the "BUG: Bad page map" message. And recent HWPOISON work has copied that code into do_swap_page(), when it finds an impossible swap entry: fix that to VM_FAULT_SIGBUS too. Signed-off-by: Hugh Dickins --- This one has nothing whatever to do with KSM swapping, just something that KAMEZAWA-san and Minchan noticed recently. mm/memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- mm5/mm/memory.c 2009-11-02 12:32:34.000000000 +0000 +++ mm6/mm/memory.c 2009-11-07 14:44:58.000000000 +0000 @@ -2529,7 +2529,7 @@ static int do_swap_page(struct mm_struct ret = VM_FAULT_HWPOISON; } else { print_bad_pte(vma, address, orig_pte, NULL); - ret = VM_FAULT_OOM; + ret = VM_FAULT_SIGBUS; } goto out; } @@ -2925,7 +2925,7 @@ static int do_nonlinear_fault(struct mm_ * Page table corrupted: show pte and kill process. */ print_bad_pte(vma, address, orig_pte, NULL); - return VM_FAULT_OOM; + return VM_FAULT_SIGBUS; } pgoff = pte_to_pgoff(orig_pte); -- 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