[PATCH] kmalloc_node IRQ safety fix

In kmalloc_node we are checking if the allocation is for the same node when
interrupts are "on". This may lead to an allocation on another node than
intended.

This patch just shifts the check for the current node in __cache_alloc_node
when interrupts are disabled.

Signed-off-by: Alok N Kataria <[e-mail]>
Acked-by: Christoph Lameter <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

mm/slab.c

···
 #define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
 #endif
 
-
-static inline void *__cache_alloc(kmem_cache_t *cachep, unsigned int __nocast flags)
+static inline void *____cache_alloc(kmem_cache_t *cachep, unsigned int __nocast flags)
 {
-	unsigned long save_flags;
 	void* objp;
 	struct array_cache *ac;
 
-	cache_alloc_debugcheck_before(cachep, flags);
-
-	local_irq_save(save_flags);
+	check_irq_off();
 	ac = ac_data(cachep);
 	if (likely(ac->avail)) {
 		STATS_INC_ALLOCHIT(cachep);
···
 		STATS_INC_ALLOCMISS(cachep);
 		objp = cache_alloc_refill(cachep, flags);
 	}
+	return objp;
+}
+
+static inline void *__cache_alloc(kmem_cache_t *cachep, unsigned int __nocast flags)
+{
+	unsigned long save_flags;
+	void* objp;
+
+	cache_alloc_debugcheck_before(cachep, flags);
+
+	local_irq_save(save_flags);
+	objp = ____cache_alloc(cachep, flags);
 	local_irq_restore(save_flags);
 	objp = cache_alloc_debugcheck_after(cachep, flags, objp,
 					__builtin_return_address(0));
···
 
 	cache_alloc_debugcheck_before(cachep, flags);
 	local_irq_save(save_flags);
-	ptr = __cache_alloc_node(cachep, flags, nodeid);
+	if (nodeid == numa_node_id())
+		ptr = ____cache_alloc(cachep, flags);
+	else
+		ptr = __cache_alloc_node(cachep, flags, nodeid);
 	local_irq_restore(save_flags);
 	ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, __builtin_return_address(0));