From: Mike Galbraith <bitbuc...@online.de>
commit 60e69eed85bb7b5198ef70643b5895c26ad76ef7 upstream
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.le...@oracle.com>
Fixes: 156654f491dd ("sched/numa: Move task_numa_free() to __put_task_struct()")
Signed-off-by: Mike Galbraith <bitbuc...@online.de>
Signed-off-by: Peter Zijlstra <pet...@infradead.org>
Cc: torva...@linux-foundation.org
Cc: mgor...@suse.com
Cc: a...@linux-foundation.org
Cc: Dave Jones <da...@redhat.com>
Link: http://lkml.kernel.org/r/1396860915.5170.5.ca...@marge.simpson.net
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Yang Shi <yang....@windriver.com>
---
kernel/sched/fair.c | 13 +++++++------
kernel/sched/sched.h | 9 +++++++++
2 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 964d4ef..356b3cc 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1514,7 +1514,7 @@ 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 */
@@ -1589,7 +1589,7 @@ 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 */
@@ -1694,7 +1694,8 @@ 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];
@@ -1708,7 +1709,7 @@ 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);
@@ -1727,14 +1728,14 @@ 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 f964add..4bcdcda 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1392,6 +1392,15 @@ 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)
--
2.0.2
--
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