[PATCH] slab: Avoid deadlock at kmem_cache_create/kmem_cache_destroy
Prevents deadlock situation between kmem_cache_create()/kmem_cache_destory(), and kmem_cache_create() /cpu hotplug. The locking order probably got moved over time. Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Shai Fultheim <shai@scalex86.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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10
mm/slab.c
10
mm/slab.c
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@ -1717,6 +1717,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
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BUG();
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}
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/*
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* Prevent CPUs from coming and going.
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* lock_cpu_hotplug() nests outside cache_chain_mutex
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*/
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lock_cpu_hotplug();
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mutex_lock(&cache_chain_mutex);
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list_for_each(p, &cache_chain) {
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@ -1918,8 +1924,6 @@ kmem_cache_create (const char *name, size_t size, size_t align,
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cachep->dtor = dtor;
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cachep->name = name;
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/* Don't let CPUs to come and go */
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lock_cpu_hotplug();
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if (g_cpucache_up == FULL) {
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enable_cpucache(cachep);
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@ -1978,12 +1982,12 @@ kmem_cache_create (const char *name, size_t size, size_t align,
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/* cache setup completed, link it into the list */
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list_add(&cachep->next, &cache_chain);
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unlock_cpu_hotplug();
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oops:
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if (!cachep && (flags & SLAB_PANIC))
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panic("kmem_cache_create(): failed to create slab `%s'\n",
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name);
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mutex_unlock(&cache_chain_mutex);
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unlock_cpu_hotplug();
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return cachep;
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}
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EXPORT_SYMBOL(kmem_cache_create);
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