[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 <alokk@calsoftinc.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/slab.c b/mm/slab.c
index c9adfce004056d2539ffa04a9ab09c1a2773d89d..5cbbdfa6dd0e75b0dbcffd490d1f6a75eb76f745 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2510,16 +2510,12 @@ cache_alloc_debugcheck_after(kmem_cache_t *cachep,
 #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);
@@ -2529,6 +2525,18 @@ static inline void *__cache_alloc(kmem_cache_t *cachep, unsigned int __nocast fl
                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));
@@ -2856,7 +2864,10 @@ void *kmem_cache_alloc_node(kmem_cache_t *cachep, unsigned int __nocast flags, i
 
        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));