linux-kernel - [PATCH RT 03/13] mm/kasan: make quarantine_lock a raw_spinlock

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Message-Id: <20190107195332.098645365@goodmis.org>
Date:   Mon, 07 Jan 2019 14:52:55 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org,
        linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        John Kacur <jkacur@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Julia Cartwright <julia@...com>,
        Daniel Wagner <daniel.wagner@...mens.com>,
        tom.zanussi@...ux.intel.com, Clark Williams <williams@...hat.com>
Subject: [PATCH RT 03/13] mm/kasan: make quarantine_lock a raw_spinlock_t

4.14.87-rt50-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Clark Williams <williams@...hat.com>

[ Upstream commit 089cb35faad5da57fa90399b230b3aee4920bb02 ]

The static lock quarantine_lock is used in 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 not a problem on a stock kernel but is problematic on an RT
kernel where spin locks are sleeping spinlocks, which can sleep and can
not be acquired with disabled interrupts.

Convert the quarantine_lock to a raw spinlock_t. 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@...hat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 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);
 
-- 
2.19.2