Commit 3406e91b authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm, slub: make locking in deactivate_slab() irq-safe 



dectivate_slab() now no longer touches the kmem_cache_cpu structure, so it will
be possible to call it with irqs enabled. Just convert the spin_lock calls to
their irq saving/restoring variants to make it irq-safe.

Note we now have to use cmpxchg_double_slab() for irq-safe slab_lock(), because
in some situations we don't take the list_lock, which would disable irqs.

Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent a019d201

mm/slub.c

+5 −4
Original line number Diff line number Diff line
@@ -2223,6 +2223,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, 
	enum slab_modes l = M_NONE, m = M_NONE;

	void *nextfree, *freelist_iter, *freelist_tail;

	int tail = DEACTIVATE_TO_HEAD;

	unsigned long flags = 0;

	struct page new;

	struct page old;
@@ -2298,7 +2299,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, 
			 * that acquire_slab() will see a slab page that

			 * is frozen

			 */

			spin_lock(&n->list_lock);

			spin_lock_irqsave(&n->list_lock, flags);

		}

	} else {

		m = M_FULL;
@@ -2309,7 +2310,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, 
			 * slabs from diagnostic functions will not see

			 * any frozen slabs.

			 */

			spin_lock(&n->list_lock);

			spin_lock_irqsave(&n->list_lock, flags);

		}

	}
@@ -2326,14 +2327,14 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, 
	}



	l = m;

	if (!__cmpxchg_double_slab(s, page,

	if (!cmpxchg_double_slab(s, page,

				old.freelist, old.counters,

				new.freelist, new.counters,

				"unfreezing slab"))

		goto redo;



	if (lock)

		spin_unlock(&n->list_lock);

		spin_unlock_irqrestore(&n->list_lock, flags);



	if (m == M_PARTIAL)

		stat(s, tail);