Commit e244c9e6 authored Apr 15, 2015 by David Rientjes Committed by Linus Torvalds Apr 15, 2015

mm, mempool: disallow mempools based on slab caches with constructors



All occurrences of mempools based on slab caches with object constructors
have been removed from the tree, so disallow creating them.

We can only dereference mem->ctor in mm/mempool.c without including
mm/slab.h in include/linux/mempool.h.  So simply note the restriction,
just like the comment restricting usage of __GFP_ZERO, and warn on kernels
with CONFIG_DEBUG_VM() if such a mempool is allocated from.

We don't want to incur this check on every element allocation, so use
VM_BUG_ON().

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ee146245

include/linux/mempool.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -36,7 +36,8 @@ extern void mempool_free(void element, mempool_t pool);

		/*
		* A mempool_alloc_t and mempool_free_t that get the memory from
		* a slab that is passed in through pool_data.
		* a slab cache that is passed in through pool_data.
		* Note: the slab cache may not have a ctor function.
		*/
		void mempool_alloc_slab(gfp_t gfp_mask, void pool_data);
		void mempool_free_slab(void element, void pool_data);

mm/mempool.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@
		#include <linux/mempool.h>
		#include <linux/blkdev.h>
		#include <linux/writeback.h>
		#include "slab.h"

		static void add_element(mempool_t pool, void element)
		{
		@@ -334,6 +335,7 @@ EXPORT_SYMBOL(mempool_free);
		void mempool_alloc_slab(gfp_t gfp_mask, void pool_data)
		{
		struct kmem_cache *mem = pool_data;
		VM_BUG_ON(mem->ctor);
		return kmem_cache_alloc(mem, gfp_mask);
		}
		EXPORT_SYMBOL(mempool_alloc_slab);

Admin message