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authorMike Galbraith <bitbucket@online.de>2014-04-07 10:55:15 +0200
committerIngo Molnar <mingo@kernel.org>2014-04-11 10:39:15 +0200
commit60e69eed85bb7b5198ef70643b5895c26ad76ef7 (patch)
tree4fa65bf81edbd0a28d5bc160f878341657f5ad82 /kernel
parent467cbd207abdbfe29514b5804a22661ab6e80dc6 (diff)
downloadlinux-60e69eed85bb7b5198ef70643b5895c26ad76ef7.tar.gz
linux-60e69eed85bb7b5198ef70643b5895c26ad76ef7.tar.xz
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 7e9bd0b..4f14a65 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1497,7 +1497,7 @@ static void task_numa_placement(struct task_struct *p)
/* If the task is part of a group prevent parallel updates to group stats */
if (p->numa_group) {
group_lock = &p->numa_group->lock;
- spin_lock(group_lock);
+ spin_lock_irq(group_lock);
}
/* Find the node with the highest number of faults */
@@ -1572,7 +1572,7 @@ static void task_numa_placement(struct task_struct *p)
}
}
- spin_unlock(group_lock);
+ spin_unlock_irq(group_lock);
}
/* 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,
if (!join)
return;
- double_lock(&my_grp->lock, &grp->lock);
+ BUG_ON(irqs_disabled());
+ double_lock_irq(&my_grp->lock, &grp->lock);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
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,
grp->nr_tasks++;
spin_unlock(&my_grp->lock);
- spin_unlock(&grp->lock);
+ spin_unlock_irq(&grp->lock);
rcu_assign_pointer(p->numa_group, grp);
@@ -1710,14 +1711,14 @@ void task_numa_free(struct task_struct *p)
void *numa_faults = p->numa_faults_memory;
if (grp) {
- spin_lock(&grp->lock);
+ spin_lock_irq(&grp->lock);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
grp->faults[i] -= p->numa_faults_memory[i];
grp->total_faults -= p->total_numa_faults;
list_del(&p->numa_entry);
grp->nr_tasks--;
- spin_unlock(&grp->lock);
+ spin_unlock_irq(&grp->lock);
rcu_assign_pointer(p->numa_group, NULL);
put_numa_group(grp);
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c9007f2..456e492 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)
spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
}
+static inline void double_lock_irq(spinlock_t *l1, spinlock_t *l2)
+{
+ if (l1 > l2)
+ swap(l1, l2);
+
+ spin_lock_irq(l1);
+ spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
+}
+
static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2)
{
if (l1 > l2)