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Date: Tue, 10 Nov 2009 22:06:49 +0000 (GMT) From: Hugh Dickins <hugh.dickins@...cali.co.uk> To: Andrew Morton <akpm@...ux-foundation.org> cc: Izik Eidus <ieidus@...hat.com>, Andrea Arcangeli <aarcange@...hat.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, Minchan Kim <minchan.kim@...il.com>, Andi Kleen <andi@...stfloor.org>, Wu Fengguang <fengguang.wu@...el.com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: [PATCH 6/6] mm: sigbus instead of abusing oom 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 <hugh.dickins@...cali.co.uk> --- 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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