From: Dave Jones <davej@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Oleg Nesterov <oleg@redhat.com>,
Darren Hart <dvhart@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Mel Gorman <mgorman@suse.de>
Subject: Re: process 'stuck' at exit.
Date: Tue, 10 Dec 2013 18:00:09 -0500 [thread overview]
Message-ID: <20131210230009.GF5050@redhat.com> (raw)
In-Reply-To: <CA+55aFzhCSvc4Vy7tEC2K972h+vne6Y0QSekDDZbV_ATB-9mxw@mail.gmail.com>
On Tue, Dec 10, 2013 at 02:48:52PM -0800, Linus Torvalds wrote:
> On Tue, Dec 10, 2013 at 2:42 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > And yes, I remember that we do not do an extra check for the fshared
> > case, because get_user_pages_fast() should do it for us already. If
> > not we are fubared not only in the futex code.
>
> Yeah. It turns out we do do the access check indirectly - by looking
> at the PAGE_USER bit, even if we don't necessarily check the actual
> limits. So get_user_pages_fast() is fine.
>
> > But there is a subtle detail:
>
> Yup, see my email from ten minutes ago, we found the same thing. And
> that would seem to explain the endless loop, and also the timing
> (since Dave mentions he started doing large-pages lately).
>
> So I think the "__get_user_pages_fast(address, 1, !ro, &page)" thing
> should work.
>
> Dave, can you re-create that trinity run and test that patch? I think
> we've got this, but it might be nice to leave the hung machine up and
> running until it's verified.. Although I don't really see what else we
> could need or get out of it, so..
The only thing I'm still unclear on, is how that pid allegedly wasn't doing
a futex call as part of its run. The only thing I can think of is that
the other pid that _did_ do a futex call did it on a page that was MAP_SHARED
between all the other children, and this 'spin forever' thing only
happens when the last process with a reference on that page exits ?
does that make sense?
Dave
next prev parent reply other threads:[~2013-12-10 23:46 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-10 15:47 process 'stuck' at exit Dave Jones
2013-12-10 18:40 ` Linus Torvalds
2013-12-10 19:18 ` Thomas Gleixner
2013-12-10 19:55 ` Linus Torvalds
2013-12-10 20:27 ` Dave Jones
2013-12-10 20:34 ` Thomas Gleixner
2013-12-10 20:55 ` Dave Jones
2013-12-10 21:25 ` Darren Hart
2013-12-10 21:28 ` Thomas Gleixner
2013-12-10 21:39 ` Steven Rostedt
2013-12-10 20:33 ` Thomas Gleixner
2013-12-10 20:43 ` Linus Torvalds
2013-12-10 21:17 ` Thomas Gleixner
2013-12-10 20:35 ` Oleg Nesterov
2013-12-10 20:49 ` Dave Jones
2013-12-10 21:06 ` Darren Hart
2013-12-10 21:12 ` Dave Jones
2013-12-10 21:18 ` Linus Torvalds
2013-12-10 21:24 ` Linus Torvalds
2013-12-10 21:32 ` Dave Jones
2013-12-10 21:49 ` Linus Torvalds
2013-12-10 21:56 ` Dave Jones
2013-12-10 21:59 ` Linus Torvalds
2013-12-10 22:07 ` Dave Jones
2013-12-11 12:45 ` Ingo Molnar
2013-12-10 21:34 ` Oleg Nesterov
2013-12-10 21:41 ` Dave Jones
2013-12-10 21:57 ` Linus Torvalds
2013-12-10 22:02 ` Dave Jones
2013-12-10 22:09 ` Oleg Nesterov
2013-12-10 22:19 ` Linus Torvalds
2013-12-10 22:33 ` Linus Torvalds
2013-12-10 22:38 ` Darren Hart
2013-12-10 22:57 ` Thomas Gleixner
2013-12-10 23:05 ` Linus Torvalds
2013-12-10 23:28 ` Thomas Gleixner
2013-12-10 23:31 ` Al Viro
2013-12-11 17:08 ` Oleg Nesterov
2013-12-11 17:18 ` Thomas Gleixner
2013-12-11 17:56 ` Oleg Nesterov
2013-12-11 19:18 ` PATCH? introduce get_compound_page (Was: process 'stuck' at exit) Oleg Nesterov
2013-12-13 15:10 ` Andrea Arcangeli
2013-12-13 16:22 ` Oleg Nesterov
2013-12-13 17:34 ` Andrea Arcangeli
2013-12-16 18:36 ` Oleg Nesterov
2013-12-16 20:19 ` Andrea Arcangeli
2013-12-16 20:46 ` Oleg Nesterov
2013-12-17 16:53 ` Oleg Nesterov
2013-12-17 18:06 ` Andrea Arcangeli
2013-12-18 19:19 ` [PATCH -mm 0/7] (Was: introduce get_compound_page) Oleg Nesterov
2013-12-18 19:19 ` [PATCH -mm 1/7] mm: thp: introduce __put_nontail_page() Oleg Nesterov
2013-12-18 19:19 ` [PATCH -mm 2/7] mm: thp: change __get_page_tail() to use __put_nontail_page() Oleg Nesterov
2013-12-18 19:19 ` [PATCH -mm 3/7] mm: change release_pages() to use put_page() rather than put_compound_page() Oleg Nesterov
2013-12-18 19:19 ` [PATCH -mm 4/7] mm: thp: turn put_compound_page() into __put_page_tail() Oleg Nesterov
2013-12-18 19:36 ` Peter Zijlstra
2013-12-18 19:50 ` Oleg Nesterov
2013-12-18 19:20 ` [PATCH -mm 5/7] mm: thp: reorganize out_put_single code in __put_page_tail() Oleg Nesterov
2013-12-18 19:20 ` [PATCH -mm 6/7] mm: thp: introduce get_lock_thp_head() Oleg Nesterov
2013-12-18 21:37 ` Linus Torvalds
2013-12-19 16:29 ` Oleg Nesterov
2013-12-18 19:20 ` [PATCH -mm 7/7] mm: thp: introduce compound_head_put_tail(), change get_futex_key() to use it Oleg Nesterov
2013-12-18 19:28 ` Peter Zijlstra
2013-12-18 19:40 ` Oleg Nesterov
2013-12-19 19:08 ` [PATCH 0/1] mm: fix the theoretical compound_lock() vs prep_new_page() race Oleg Nesterov
2013-12-19 19:09 ` [PATCH 1/1] " Oleg Nesterov
2013-12-23 11:43 ` Andrea Arcangeli
2014-01-03 19:55 ` [PATCH v2 0/1] " Oleg Nesterov
2014-01-03 19:55 ` [PATCH v2 1/1] " Oleg Nesterov
2014-01-03 21:00 ` Andrew Morton
2014-01-04 16:43 ` Oleg Nesterov
2014-01-08 11:54 ` Mel Gorman
2014-01-08 13:14 ` Mel Gorman
2014-01-08 16:13 ` Oleg Nesterov
2014-01-08 18:02 ` Mel Gorman
2014-01-08 19:04 ` Oleg Nesterov
2014-01-09 11:27 ` Mel Gorman
2014-01-09 14:04 ` Oleg Nesterov
2014-01-09 18:52 ` Andrea Arcangeli
2014-01-09 19:43 ` Oleg Nesterov
2014-01-09 21:36 ` Andrea Arcangeli
2014-01-10 16:12 ` Oleg Nesterov
2014-01-10 16:50 ` Peter Zijlstra
2014-01-10 16:12 ` Mel Gorman
2013-12-20 14:19 ` [PATCH 0/1] " Martin Schwidefsky
2013-12-16 20:19 ` [PATCH 0/2] mm: thp: get_huge_page_tail() cleanups Oleg Nesterov
2013-12-16 20:19 ` [PATCH -mm 1/2] mm: thp: __get_page_tail_foll() can use get_huge_page_tail() Oleg Nesterov
2013-12-16 20:19 ` [PATCH -mm 2/2] mm: thp: turn compound_head() into BUG_ON(!PageTail) in get_huge_page_tail() Oleg Nesterov
2013-12-16 20:27 ` [PATCH 0/2] mm: thp: get_huge_page_tail() cleanups Andrea Arcangeli
2013-12-10 22:42 ` process 'stuck' at exit Thomas Gleixner
2013-12-10 22:48 ` Linus Torvalds
2013-12-10 22:58 ` Darren Hart
2013-12-10 23:01 ` Dave Jones
2013-12-10 23:00 ` Dave Jones [this message]
2013-12-11 0:05 ` Steven Rostedt
2013-12-11 0:23 ` Dave Jones
2013-12-11 0:55 ` Dave Jones
2013-12-14 20:17 ` Oleg Nesterov
2013-12-11 4:09 ` Dave Jones
2013-12-12 4:26 ` Dave Jones
2013-12-12 5:29 ` Darren Hart
2013-12-10 22:51 ` Darren Hart
2013-12-10 23:24 ` Al Viro
2013-12-11 16:31 ` Mel Gorman
2013-12-11 16:38 ` Thomas Gleixner
2013-12-11 17:57 ` Mel Gorman
2013-12-12 19:00 ` Andrea Arcangeli
2013-12-12 19:03 ` Linus Torvalds
2013-12-10 22:09 ` Steven Rostedt
2013-12-10 22:16 ` Dave Jones
2013-12-10 22:21 ` Steven Rostedt
2013-12-10 22:27 ` Dave Jones
2013-12-11 1:02 ` Mel Gorman
2013-12-10 20:57 ` Darren Hart
2013-12-10 21:09 ` Dave Jones
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