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Subject[PATCH RT] rt: convert mm/kasan/quarantine_lock to raw_spinlock
Date
The static lock quarantine_lock is used in mm/kasan/quarantine.c to protect
the quarantine queue datastructures. It is taken inside quarantine queue
manipulation routines (quarantine_put(), quarantine_reduce() and quarantine_remove_cache()),
with IRQs disabled. This is no problem on a stock kernel but is problematic
on an RT kernel where spin locks are converted to rt_mutex_t, which can sleep.

Convert the quarantine_lock to a raw spinlock. The usage of quarantine_lock
is confined to quarantine.c and the work performed while the lock is held is limited.

Signed-off-by: Clark Williams <williams@redhat.com>
---
mm/kasan/quarantine.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 3a8ddf8baf7d..b209dbaefde8 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -103,7 +103,7 @@ static int quarantine_head;
static int quarantine_tail;
/* Total size of all objects in global_quarantine across all batches. */
static unsigned long quarantine_size;
-static DEFINE_SPINLOCK(quarantine_lock);
+static DEFINE_RAW_SPINLOCK(quarantine_lock);
DEFINE_STATIC_SRCU(remove_cache_srcu);

/* Maximum size of the global queue. */
@@ -190,7 +190,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache)
if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) {
qlist_move_all(q, &temp);

- spin_lock(&quarantine_lock);
+ raw_spin_lock(&quarantine_lock);
WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes);
qlist_move_all(&temp, &global_quarantine[quarantine_tail]);
if (global_quarantine[quarantine_tail].bytes >=
@@ -203,7 +203,7 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache)
if (new_tail != quarantine_head)
quarantine_tail = new_tail;
}
- spin_unlock(&quarantine_lock);
+ raw_spin_unlock(&quarantine_lock);
}

local_irq_restore(flags);
@@ -230,7 +230,7 @@ void quarantine_reduce(void)
* expected case).
*/
srcu_idx = srcu_read_lock(&remove_cache_srcu);
- spin_lock_irqsave(&quarantine_lock, flags);
+ raw_spin_lock_irqsave(&quarantine_lock, flags);

/*
* Update quarantine size in case of hotplug. Allocate a fraction of
@@ -254,7 +254,7 @@ void quarantine_reduce(void)
quarantine_head = 0;
}

- spin_unlock_irqrestore(&quarantine_lock, flags);
+ raw_spin_unlock_irqrestore(&quarantine_lock, flags);

qlist_free_all(&to_free, NULL);
srcu_read_unlock(&remove_cache_srcu, srcu_idx);
@@ -310,17 +310,17 @@ void quarantine_remove_cache(struct kmem_cache *cache)
*/
on_each_cpu(per_cpu_remove_cache, cache, 1);

- spin_lock_irqsave(&quarantine_lock, flags);
+ raw_spin_lock_irqsave(&quarantine_lock, flags);
for (i = 0; i < QUARANTINE_BATCHES; i++) {
if (qlist_empty(&global_quarantine[i]))
continue;
qlist_move_cache(&global_quarantine[i], &to_free, cache);
/* Scanning whole quarantine can take a while. */
- spin_unlock_irqrestore(&quarantine_lock, flags);
+ raw_spin_unlock_irqrestore(&quarantine_lock, flags);
cond_resched();
- spin_lock_irqsave(&quarantine_lock, flags);
+ raw_spin_lock_irqsave(&quarantine_lock, flags);
}
- spin_unlock_irqrestore(&quarantine_lock, flags);
+ raw_spin_unlock_irqrestore(&quarantine_lock, flags);

qlist_free_all(&to_free, cache);

--
2.17.1
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