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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@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2009-12-14 17:59:04 -08:00 committed by Linus Torvalds
parent a70caa8ba4
commit d99be1a8ec
1 changed files with 2 additions and 2 deletions
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4
mm/memory.c
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@ -2527,7 +2527,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
ret = VM_FAULT_HWPOISON; ret = VM_FAULT_HWPOISON;
} else { } else {
print_bad_pte(vma, address, orig_pte, NULL); print_bad_pte(vma, address, orig_pte, NULL);
ret = VM_FAULT_OOM; ret = VM_FAULT_SIGBUS;
} }
goto out; 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. * Page table corrupted: show pte and kill process.
*/ */
print_bad_pte(vma, address, orig_pte, NULL); print_bad_pte(vma, address, orig_pte, NULL);
return VM_FAULT_OOM; return VM_FAULT_SIGBUS;
} }
pgoff = pte_to_pgoff(orig_pte); pgoff = pte_to_pgoff(orig_pte);