linux-kernel - Re: fs: uninterruptible hang in handle

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Date:	Tue, 1 Mar 2016 12:28:25 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: fs: uninterruptible hang in handle_userfault

On Tue, Mar 1, 2016 at 11:56 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> (The above patches are entirely untested, maybe I misread the reason
> it might be hanging and it's something else going on).

Ok, I did some half-arsed testing. I didn't have a kernel with
USERFAULT enabled, but I did compile one with both patches in place
and I don't see a hang with the test program. Of course, since I
didn't test with an unpatched kernel that would show the hang in the
first place, it's entirely possible that my "no hang" result is due to
something else. And I didn't bother to test the two patches
independently either.

But at least on the face of it, those patches fix the problem. Dmitry?

              Linus