From: Oleg Nesterov <oleg@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Jones <davej@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
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: Wed, 11 Dec 2013 18:08:44 +0100 [thread overview]
Message-ID: <20131211170844.GA21700@redhat.com> (raw)
In-Reply-To: <CA+55aFw_emAUOr5BYx0TfTCGEOrW6-ZRATWbm00DvCXsGD7=DQ@mail.gmail.com>
On 12/10, Linus Torvalds wrote:
>
> I think what happens is:
> - get_user_pages_fast(address, 1, 1, &page) fails (because it's read-only)
> - get_user_pages_fast(address, 1, 0, &page) succeeds and gets a large-page
> - __get_user_pages_fast(address, 1, 1, &page) fails (because it's read-only).
>
> so what triggers this is likely that Dave now does large-pages, and
> one of them is a read-only mapping.
>
> So I would suggest replacing the second "1" in the
> __get_user_pages_fast() call with a "!ro" instead. So how about this
> second patch instead (the access_ok() move remains).
I know almost nothing about THP, but why we may need write == true in
this case?
IOW,
> - if (likely(__get_user_pages_fast(address, 1, 1, &page) == 1)) {
> + if (likely(__get_user_pages_fast(address, 1, !ro, &page) == 1)) {
can't
if (likely(__get_user_pages_fast(address, 1, 0, &page) == 1)) {
work?
I have to admit, I do not understand why we can't avoid this altogether.
__get_page_tail() can find the stable ->first_page, why get_futex_key()
can't ?
Oleg.
next prev parent reply other threads:[~2013-12-11 17:08 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 [this message]
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
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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