Commit cfdf836e authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm, slub: call deactivate_slab() without disabling irqs 



The function is now safe to be called with irqs enabled, so move the calls
outside of irq disabled sections.

When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so to
reenable them before deactivate_slab() we need to open-code flush_slab() in
___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fields.
But that means a IRQ handler meanwhile might have assigned a new page to
kmem_cache_cpu.page so we have to retry the whole check.

The remaining callers of flush_slab() are the IPI handler which has disabled
irqs anyway, and slub_cpu_dead() which will be dealt with in the following
patch.

Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent 3406e91b

mm/slub.c

+19 −5
Original line number Diff line number Diff line
@@ -2779,8 +2779,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, 
	freelist = c->freelist;

	c->page = NULL;

	c->freelist = NULL;

	deactivate_slab(s, page, freelist);

	local_irq_restore(flags);

	deactivate_slab(s, page, freelist);



new_slab:
@@ -2848,18 +2848,32 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, 
		 */

		goto return_single;



retry_load_page:



	local_irq_save(flags);

	if (unlikely(c->page))

		flush_slab(s, c);

	if (unlikely(c->page)) {

		void *flush_freelist = c->freelist;

		struct page *flush_page = c->page;



		c->page = NULL;

		c->freelist = NULL;

		c->tid = next_tid(c->tid);



		local_irq_restore(flags);



		deactivate_slab(s, flush_page, flush_freelist);



		stat(s, CPUSLAB_FLUSH);



		goto retry_load_page;

	}

	c->page = page;



	goto load_freelist;



return_single:



	local_irq_save(flags);

	deactivate_slab(s, page, get_freepointer(s, freelist));

	local_irq_restore(flags);

	return freelist;

}