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From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>, Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@suse.de>
Subject: [PATCH 05/63] mm: Wait for THP migrations to complete during NUMA hinting faults
Date: Mon,  7 Oct 2013 11:28:43 +0100
Message-ID: <1381141781-10992-6-git-send-email-mgorman@suse.de> (raw)
In-Reply-To: <1381141781-10992-1-git-send-email-mgorman@suse.de>

The locking for migrating THP is unusual. While normal page migration
prevents parallel accesses using a migration PTE, THP migration relies on
a combination of the page_table_lock, the page lock and the existance of
the NUMA hinting PTE to guarantee safety but there is a bug in the scheme.

If a THP page is currently being migrated and another thread traps a
fault on the same page it checks if the page is misplaced. If it is not,
then pmd_numa is cleared. The problem is that it checks if the page is
misplaced without holding the page lock meaning that the racing thread
can be migrating the THP when the second thread clears the NUMA bit
and faults a stale page.

This patch checks if the page is potentially being migrated and stalls
using the lock_page if it is potentially being migrated before checking
if the page is misplaced or not.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 mm/huge_memory.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index dab2bab..f362363 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1295,13 +1295,14 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (current_nid == numa_node_id())
 		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
 
-	target_nid = mpol_misplaced(page, vma, haddr);
-	if (target_nid == -1) {
-		put_page(page);
-		goto clear_pmdnuma;
-	}
+	/*
+	 * Acquire the page lock to serialise THP migrations but avoid dropping
+	 * page_table_lock if at all possible
+	 */
+	if (trylock_page(page))
+		goto got_lock;
 
-	/* Acquire the page lock to serialise THP migrations */
+	/* Serialise against migrationa and check placement check placement */
 	spin_unlock(&mm->page_table_lock);
 	lock_page(page);
 
@@ -1312,9 +1313,17 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		put_page(page);
 		goto out_unlock;
 	}
-	spin_unlock(&mm->page_table_lock);
+
+got_lock:
+	target_nid = mpol_misplaced(page, vma, haddr);
+	if (target_nid == -1) {
+		unlock_page(page);
+		put_page(page);
+		goto clear_pmdnuma;
+	}
 
 	/* Migrate the THP to the requested node */
+	spin_unlock(&mm->page_table_lock);
 	migrated = migrate_misplaced_transhuge_page(mm, vma,
 				pmdp, pmd, addr, page, target_nid);
 	if (!migrated)
-- 
1.8.4

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  parent reply index

Thread overview: 136+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-07 10:28 [PATCH 0/63] Basic scheduler support for automatic NUMA balancing V9 Mel Gorman
2013-10-07 10:28 ` [PATCH 01/63] hotplug: Optimize {get,put}_online_cpus() Mel Gorman
2013-10-07 10:28 ` [PATCH 02/63] mm: numa: Document automatic NUMA balancing sysctls Mel Gorman
2013-10-07 12:46   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 03/63] sched, numa: Comment fixlets Mel Gorman
2013-10-07 12:46   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 04/63] mm: numa: Do not account for a hinting fault if we raced Mel Gorman
2013-10-07 12:47   ` Rik van Riel
2013-10-07 10:28 ` Mel Gorman [this message]
2013-10-07 13:55   ` [PATCH 05/63] mm: Wait for THP migrations to complete during NUMA hinting faults Rik van Riel
2013-10-07 10:28 ` [PATCH 06/63] mm: Prevent parallel splits during THP migration Mel Gorman
2013-10-07 14:01   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 07/63] mm: numa: Sanitize task_numa_fault() callsites Mel Gorman
2013-10-07 14:02   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 08/63] mm: Close races between THP migration and PMD numa clearing Mel Gorman
2013-10-07 14:02   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 09/63] mm: Account for a THP NUMA hinting update as one PTE update Mel Gorman
2013-10-07 14:02   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 10/63] mm: Do not flush TLB during protection change if !pte_present && !migration_entry Mel Gorman
2013-10-07 15:12   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 11/63] mm: Only flush TLBs if a transhuge PMD is modified for NUMA pte scanning Mel Gorman
2013-10-07 10:28 ` [PATCH 12/63] mm: numa: Do not migrate or account for hinting faults on the zero page Mel Gorman
2013-10-07 17:10   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 13/63] sched: numa: Mitigate chance that same task always updates PTEs Mel Gorman
2013-10-07 17:24   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 14/63] sched: numa: Continue PTE scanning even if migrate rate limited Mel Gorman
2013-10-07 17:24   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 15/63] Revert "mm: sched: numa: Delay PTE scanning until a task is scheduled on a new node" Mel Gorman
2013-10-07 17:42   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 16/63] sched: numa: Initialise numa_next_scan properly Mel Gorman
2013-10-07 17:44   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 17/63] sched: Set the scan rate proportional to the memory usage of the task being scanned Mel Gorman
2013-10-07 17:44   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 18/63] sched: numa: Slow scan rate if no NUMA hinting faults are being recorded Mel Gorman
2013-10-07 18:02   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 19/63] sched: Track NUMA hinting faults on per-node basis Mel Gorman
2013-10-07 18:02   ` Rik van Riel
2013-12-04  5:32   ` Wanpeng Li
2013-12-04  5:37     ` Wanpeng Li
2013-10-07 10:28 ` [PATCH 20/63] sched: Select a preferred node with the most numa hinting faults Mel Gorman
2013-10-07 18:04   ` Rik van Riel
2013-10-07 10:28 ` [PATCH 21/63] sched: Update NUMA hinting faults once per scan Mel Gorman
2013-10-07 18:39   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 22/63] sched: Favour moving tasks towards the preferred node Mel Gorman
2013-10-07 18:39   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 23/63] sched: Resist moving tasks towards nodes with fewer hinting faults Mel Gorman
2013-10-07 18:40   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 24/63] sched: Reschedule task on preferred NUMA node once selected Mel Gorman
2013-10-07 18:40   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 25/63] sched: Add infrastructure for split shared/private accounting of NUMA hinting faults Mel Gorman
2013-10-07 18:41   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 26/63] sched: Check current->mm before allocating NUMA faults Mel Gorman
2013-10-07 18:41   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 27/63] mm: numa: Scan pages with elevated page_mapcount Mel Gorman
2013-10-07 18:43   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 28/63] sched: Remove check that skips small VMAs Mel Gorman
2013-10-07 18:44   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 29/63] sched: Set preferred NUMA node based on number of private faults Mel Gorman
2013-10-07 18:45   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 30/63] sched: Do not migrate memory immediately after switching node Mel Gorman
2013-10-07 10:29 ` [PATCH 31/63] mm: numa: only unmap migrate-on-fault VMAs Mel Gorman
2013-10-07 10:29 ` [PATCH 32/63] sched: Avoid overloading CPUs on a preferred NUMA node Mel Gorman
2013-10-07 18:58   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 33/63] sched: Retry migration of tasks to CPU on a preferred node Mel Gorman
2013-10-07 18:58   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 34/63] sched: numa: increment numa_migrate_seq when task runs in correct location Mel Gorman
2013-10-07 10:29 ` [PATCH 35/63] sched: numa: Do not trap hinting faults for shared libraries Mel Gorman
2013-10-07 19:04   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 36/63] mm: numa: Only trap pmd hinting faults if we would otherwise trap PTE faults Mel Gorman
2013-10-07 19:06   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 37/63] stop_machine: Introduce stop_two_cpus() Mel Gorman
2013-10-07 10:29 ` [PATCH 38/63] sched: Introduce migrate_swap() Mel Gorman
2013-10-07 19:06   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 39/63] sched: numa: Use a system-wide search to find swap/migration candidates Mel Gorman
2013-10-07 19:07   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 40/63] sched: numa: Favor placing a task on the preferred node Mel Gorman
2013-10-07 19:07   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 41/63] sched: numa: fix placement of workloads spread across multiple nodes Mel Gorman
2013-10-07 10:29 ` [PATCH 42/63] mm: numa: Change page last {nid,pid} into {cpu,pid} Mel Gorman
2013-10-07 19:08   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 43/63] sched: numa: Use {cpu, pid} to create task groups for shared faults Mel Gorman
2013-10-07 19:09   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 44/63] sched: numa: Report a NUMA task group ID Mel Gorman
2013-10-07 19:09   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 45/63] mm: numa: copy cpupid on page migration Mel Gorman
2013-10-07 10:29 ` [PATCH 46/63] mm: numa: Do not group on RO pages Mel Gorman
2013-10-07 19:10   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 47/63] mm: numa: Do not batch handle PMD pages Mel Gorman
2013-10-07 19:11   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 48/63] sched: numa: stay on the same node if CLONE_VM Mel Gorman
2013-10-07 10:29 ` [PATCH 49/63] sched: numa: use group fault statistics in numa placement Mel Gorman
2013-10-07 10:29 ` [PATCH 50/63] sched: numa: call task_numa_free from do_execve Mel Gorman
2013-10-07 10:29 ` [PATCH 51/63] sched: numa: Prevent parallel updates to group stats during placement Mel Gorman
2013-10-07 19:13   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 52/63] sched: numa: add debugging Mel Gorman
2013-10-07 19:13   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 53/63] sched: numa: Decide whether to favour task or group weights based on swap candidate relationships Mel Gorman
2013-10-07 10:29 ` [PATCH 54/63] sched: numa: fix task or group comparison Mel Gorman
2013-10-07 10:29 ` [PATCH 55/63] sched: numa: Avoid migrating tasks that are placed on their preferred node Mel Gorman
2013-10-07 19:14   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 56/63] sched: numa: be more careful about joining numa groups Mel Gorman
2013-10-07 10:29 ` [PATCH 57/63] sched: numa: Take false sharing into account when adapting scan rate Mel Gorman
2013-10-07 19:14   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 58/63] sched: numa: adjust scan rate in task_numa_placement Mel Gorman
2013-10-07 10:29 ` [PATCH 59/63] sched: numa: Remove the numa_balancing_scan_period_reset sysctl Mel Gorman
2013-10-07 19:14   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 60/63] mm: numa: revert temporarily disabling of NUMA migration Mel Gorman
2013-10-07 10:29 ` [PATCH 61/63] sched: numa: skip some page migrations after a shared fault Mel Gorman
2013-10-07 10:29 ` [PATCH 62/63] sched: numa: use unsigned longs for numa group fault stats Mel Gorman
2013-10-07 19:15   ` Rik van Riel
2013-10-07 10:29 ` [PATCH 63/63] sched: numa: periodically retry task_numa_migrate Mel Gorman
2013-10-09 11:03 ` [PATCH 0/63] Basic scheduler support for automatic NUMA balancing V9 Ingo Molnar
2013-10-09 11:11   ` Ingo Molnar
2013-10-09 11:13     ` Ingo Molnar
2013-10-09 12:05   ` Peter Zijlstra
2013-10-09 12:48     ` Ingo Molnar
2013-10-10  7:05   ` Mel Gorman
2013-10-09 16:28 ` Ingo Molnar
2013-10-09 16:29   ` Ingo Molnar
2013-10-09 16:57     ` Ingo Molnar
2013-10-09 17:09       ` Ingo Molnar
2013-10-09 17:11         ` Peter Zijlstra
2013-10-09 17:08   ` Peter Zijlstra
2013-10-09 17:15     ` Ingo Molnar
2013-10-09 17:18       ` Peter Zijlstra
2013-10-24 12:26 ` Automatic NUMA balancing patches for tip-urgent/stable Mel Gorman
2013-10-26 12:11   ` Ingo Molnar
2013-10-29  9:42     ` Mel Gorman
2013-10-29  9:48       ` Ingo Molnar
2013-10-29 10:24         ` Mel Gorman
2013-10-29 10:41           ` Ingo Molnar
2013-10-29 12:48             ` Mel Gorman
2013-10-31  9:51   ` [RFC GIT PULL] NUMA-balancing memory corruption fixes Ingo Molnar
2013-10-31 22:25     ` Linus Torvalds
2013-11-01  7:36       ` Ingo Molnar
  -- strict thread matches above, loose matches on Subject: below --
2013-09-27 13:26 [PATCH 0/63] Basic scheduler support for automatic NUMA balancing V8 Mel Gorman
2013-09-27 13:26 ` [PATCH 05/63] mm: Wait for THP migrations to complete during NUMA hinting faults Mel Gorman

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