Commit d99be1a8 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds

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: default avatarHugh 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: default avatarKOSAKI 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: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a70caa8b
......@@ -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);
......
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