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authorMike Galbraith <bitbucket@online.de>2014-04-07 04:55:15 -0400
committerIngo Molnar <mingo@kernel.org>2014-04-11 04:39:15 -0400
commit60e69eed85bb7b5198ef70643b5895c26ad76ef7 (patch)
tree4fa65bf81edbd0a28d5bc160f878341657f5ad82 /kernel
parent467cbd207abdbfe29514b5804a22661ab6e80dc6 (diff)
sched/numa: Fix task_numa_free() lockdep splat
Sasha reported that lockdep claims that the following commit: made numa_group.lock interrupt unsafe: 156654f491dd ("sched/numa: Move task_numa_free() to __put_task_struct()") While I don't see how that could be, given the commit in question moved task_numa_free() from one irq enabled region to another, the below does make both gripes and lockups upon gripe with numa=fake=4 go away. Reported-by: Sasha Levin <sasha.levin@oracle.com> Fixes: 156654f491dd ("sched/numa: Move task_numa_free() to __put_task_struct()") Signed-off-by: Mike Galbraith <bitbucket@online.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: torvalds@linux-foundation.org Cc: mgorman@suse.com Cc: akpm@linux-foundation.org Cc: Dave Jones <davej@redhat.com> Link: http://lkml.kernel.org/r/1396860915.5170.5.camel@marge.simpson.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/fair.c13
-rw-r--r--kernel/sched/sched.h9
2 files changed, 16 insertions, 6 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7e9bd0b1fa9e..4f14a656a720 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1497,7 +1497,7 @@ static void task_numa_placement(struct task_struct *p)
1497 /* If the task is part of a group prevent parallel updates to group stats */ 1497 /* If the task is part of a group prevent parallel updates to group stats */
1498 if (p->numa_group) { 1498 if (p->numa_group) {
1499 group_lock = &p->numa_group->lock; 1499 group_lock = &p->numa_group->lock;
1500 spin_lock(group_lock); 1500 spin_lock_irq(group_lock);
1501 } 1501 }
1502 1502
1503 /* Find the node with the highest number of faults */ 1503 /* Find the node with the highest number of faults */
@@ -1572,7 +1572,7 @@ static void task_numa_placement(struct task_struct *p)
1572 } 1572 }
1573 } 1573 }
1574 1574
1575 spin_unlock(group_lock); 1575 spin_unlock_irq(group_lock);
1576 } 1576 }
1577 1577
1578 /* Preferred node as the node with the most faults */ 1578 /* Preferred node as the node with the most faults */
@@ -1677,7 +1677,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
1677 if (!join) 1677 if (!join)
1678 return; 1678 return;
1679 1679
1680 double_lock(&my_grp->lock, &grp->lock); 1680 BUG_ON(irqs_disabled());
1681 double_lock_irq(&my_grp->lock, &grp->lock);
1681 1682
1682 for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { 1683 for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
1683 my_grp->faults[i] -= p->numa_faults_memory[i]; 1684 my_grp->faults[i] -= p->numa_faults_memory[i];
@@ -1691,7 +1692,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
1691 grp->nr_tasks++; 1692 grp->nr_tasks++;
1692 1693
1693 spin_unlock(&my_grp->lock); 1694 spin_unlock(&my_grp->lock);
1694 spin_unlock(&grp->lock); 1695 spin_unlock_irq(&grp->lock);
1695 1696
1696 rcu_assign_pointer(p->numa_group, grp); 1697 rcu_assign_pointer(p->numa_group, grp);
1697 1698
@@ -1710,14 +1711,14 @@ void task_numa_free(struct task_struct *p)
1710 void *numa_faults = p->numa_faults_memory; 1711 void *numa_faults = p->numa_faults_memory;
1711 1712
1712 if (grp) { 1713 if (grp) {
1713 spin_lock(&grp->lock); 1714 spin_lock_irq(&grp->lock);
1714 for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) 1715 for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
1715 grp->faults[i] -= p->numa_faults_memory[i]; 1716 grp->faults[i] -= p->numa_faults_memory[i];
1716 grp->total_faults -= p->total_numa_faults; 1717 grp->total_faults -= p->total_numa_faults;
1717 1718
1718 list_del(&p->numa_entry); 1719 list_del(&p->numa_entry);
1719 grp->nr_tasks--; 1720 grp->nr_tasks--;
1720 spin_unlock(&grp->lock); 1721 spin_unlock_irq(&grp->lock);
1721 rcu_assign_pointer(p->numa_group, NULL); 1722 rcu_assign_pointer(p->numa_group, NULL);
1722 put_numa_group(grp); 1723 put_numa_group(grp);
1723 } 1724 }
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c9007f28d3a2..456e492a3dca 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1385,6 +1385,15 @@ static inline void double_lock(spinlock_t *l1, spinlock_t *l2)
1385 spin_lock_nested(l2, SINGLE_DEPTH_NESTING); 1385 spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
1386} 1386}
1387 1387
1388static inline void double_lock_irq(spinlock_t *l1, spinlock_t *l2)
1389{
1390 if (l1 > l2)
1391 swap(l1, l2);
1392
1393 spin_lock_irq(l1);
1394 spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
1395}
1396
1388static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2) 1397static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2)
1389{ 1398{
1390 if (l1 > l2) 1399 if (l1 > l2)