From d99be1a8ecf377c2c9b3372d36411ad6547bbd4c Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 14 Dec 2009 17:59:04 -0800 Subject: [PATCH] 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 Cc: Izik Eidus Cc: Andrea Arcangeli Cc: Nick Piggin Reviewed-by: KOSAKI Motohiro Cc: Rik van Riel Cc: Lee Schermerhorn Cc: Andi Kleen Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: Wu Fengguang Reviewed-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 543c446bf4ed..1c9dc46da3db 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2527,7 +2527,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, ret = VM_FAULT_HWPOISON; } else { print_bad_pte(vma, address, orig_pte, NULL); - ret = VM_FAULT_OOM; + ret = VM_FAULT_SIGBUS; } goto out; } @@ -2923,7 +2923,7 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, * 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);