Re: [PATCH 6/6] mm: sigbus instead of abusing oom

From: KAMEZAWA Hiroyuki
Date: Tue Nov 10 2009 - 21:40:13 EST


On Tue, 10 Nov 2009 22:06:49 +0000 (GMT)
Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx> wrote:

> 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@xxxxxxxxxxxxx>

Thank you !
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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