From: Andrea Arcangeli <aarcange@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Dave Jones <davej@redhat.com>,
Darren Hart <dvhart@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Mel Gorman <mgorman@suse.de>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [PATCH 1/1] mm: fix the theoretical compound_lock() vs prep_new_page() race
Date: Mon, 23 Dec 2013 12:43:00 +0100 [thread overview]
Message-ID: <20131223114300.GC727@redhat.com> (raw)
In-Reply-To: <20131219190920.GB24566@redhat.com>
On Thu, Dec 19, 2013 at 08:09:20PM +0100, Oleg Nesterov wrote:
> get/put_page(thp_tail) paths do get_page_unless_zero(page_head) +
> compound_lock(). In theory this page_head can be already freed and
> reallocated as alloc_pages(__GFP_COMP, smaller_order). In this case
> get_page_unless_zero() can succeed right after set_page_refcounted(),
> and compound_lock() can race with the non-atomic __SetPageHead().
>
> Perhaps we should rework the thp locking (under discussion), but
> until then this patch moves set_page_refcounted() and adds wmb()
> to ensure that page->_count != 0 comes as a last change.
>
> I am not sure about other callers of set_page_refcounted(), but at
> first glance they look fine to me.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Only one improvement possible, the smp_wmb() could have been put under
CONFIG_TRANSPARENT_HUGEPAGE somehow. No difference for x86-64 though.
Thanks,
Andrea
next prev parent reply other threads:[~2013-12-23 11:43 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 [this message]
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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