From 68126702b419fd26ef4946e314bb3a1f57d3a53f Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 24 Oct 2013 10:07:42 +0900 Subject: slab: overloading the RCU head over the LRU for RCU free With build-time size checking, we can overload the RCU head over the LRU of struct page to free pages of a slab in rcu context. This really help to implement to overload the struct slab over the struct page and this eventually reduce memory usage and cache footprint of the SLAB. Acked-by: Andi Kleen Acked-by: Christoph Lameter Signed-off-by: Joonsoo Kim Signed-off-by: Pekka Enberg --- include/linux/slab.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index 6c5cc0ea8713..caaad51fee1f 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -51,7 +51,14 @@ * } * rcu_read_unlock(); * - * See also the comment on struct slab_rcu in mm/slab.c. + * This is useful if we need to approach a kernel structure obliquely, + * from its address obtained without the usual locking. We can lock + * the structure to stabilize it and check it's still at the given address, + * only if we can be sure that the memory has not been meanwhile reused + * for some other kind of object (which our subsystem's lock might corrupt). + * + * rcu_read_lock before reading the address, then rcu_read_unlock after + * taking the spinlock within the structure expected at that address. */ #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */ #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */ -- cgit v1.2.3-71-gd317 From 7e3528c3660a2e8602abc7858b0994d611f74bc3 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 22 Nov 2013 18:14:38 -0800 Subject: slab.h: remove duplicate kmalloc declaration and fix kernel-doc warnings Fix kernel-doc warning for duplicate definition of 'kmalloc': Documentation/DocBook/kernel-api.xml:9483: element refentry: validity error : ID API-kmalloc already defined Also combine the kernel-doc info from the 2 kmalloc definitions into one block and remove the "see kcalloc" comment since kmalloc now contains the @flags info. Signed-off-by: Randy Dunlap Acked-by: Christoph Lameter Signed-off-by: Linus Torvalds --- include/linux/slab.h | 102 +++++++++++++++++++++++---------------------------- 1 file changed, 46 insertions(+), 56 deletions(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index c2bba248fa63..1e2f4fe12773 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -388,10 +388,55 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags) /** * kmalloc - allocate memory * @size: how many bytes of memory are required. - * @flags: the type of memory to allocate (see kcalloc). + * @flags: the type of memory to allocate. * * kmalloc is the normal method of allocating memory * for objects smaller than page size in the kernel. + * + * The @flags argument may be one of: + * + * %GFP_USER - Allocate memory on behalf of user. May sleep. + * + * %GFP_KERNEL - Allocate normal kernel ram. May sleep. + * + * %GFP_ATOMIC - Allocation will not sleep. May use emergency pools. + * For example, use this inside interrupt handlers. + * + * %GFP_HIGHUSER - Allocate pages from high memory. + * + * %GFP_NOIO - Do not do any I/O at all while trying to get memory. + * + * %GFP_NOFS - Do not make any fs calls while trying to get memory. + * + * %GFP_NOWAIT - Allocation will not sleep. + * + * %GFP_THISNODE - Allocate node-local memory only. + * + * %GFP_DMA - Allocation suitable for DMA. + * Should only be used for kmalloc() caches. Otherwise, use a + * slab created with SLAB_DMA. + * + * Also it is possible to set different flags by OR'ing + * in one or more of the following additional @flags: + * + * %__GFP_COLD - Request cache-cold pages instead of + * trying to return cache-warm pages. + * + * %__GFP_HIGH - This allocation has high priority and may use emergency pools. + * + * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail + * (think twice before using). + * + * %__GFP_NORETRY - If memory is not immediately available, + * then give up at once. + * + * %__GFP_NOWARN - If allocation fails, don't issue any warnings. + * + * %__GFP_REPEAT - If allocation fails initially, try once more before failing. + * + * There are other flags available as well, but these are not intended + * for general use, and so are not documented here. For a full list of + * potential flags, always refer to linux/gfp.h. */ static __always_inline void *kmalloc(size_t size, gfp_t flags) { @@ -501,61 +546,6 @@ struct seq_file; int cache_show(struct kmem_cache *s, struct seq_file *m); void print_slabinfo_header(struct seq_file *m); -/** - * kmalloc - allocate memory - * @size: how many bytes of memory are required. - * @flags: the type of memory to allocate. - * - * The @flags argument may be one of: - * - * %GFP_USER - Allocate memory on behalf of user. May sleep. - * - * %GFP_KERNEL - Allocate normal kernel ram. May sleep. - * - * %GFP_ATOMIC - Allocation will not sleep. May use emergency pools. - * For example, use this inside interrupt handlers. - * - * %GFP_HIGHUSER - Allocate pages from high memory. - * - * %GFP_NOIO - Do not do any I/O at all while trying to get memory. - * - * %GFP_NOFS - Do not make any fs calls while trying to get memory. - * - * %GFP_NOWAIT - Allocation will not sleep. - * - * %GFP_THISNODE - Allocate node-local memory only. - * - * %GFP_DMA - Allocation suitable for DMA. - * Should only be used for kmalloc() caches. Otherwise, use a - * slab created with SLAB_DMA. - * - * Also it is possible to set different flags by OR'ing - * in one or more of the following additional @flags: - * - * %__GFP_COLD - Request cache-cold pages instead of - * trying to return cache-warm pages. - * - * %__GFP_HIGH - This allocation has high priority and may use emergency pools. - * - * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail - * (think twice before using). - * - * %__GFP_NORETRY - If memory is not immediately available, - * then give up at once. - * - * %__GFP_NOWARN - If allocation fails, don't issue any warnings. - * - * %__GFP_REPEAT - If allocation fails initially, try once more before failing. - * - * There are other flags available as well, but these are not intended - * for general use, and so are not documented here. For a full list of - * potential flags, always refer to linux/gfp.h. - * - * kmalloc is the normal method of allocating memory - * in the kernel. - */ -static __always_inline void *kmalloc(size_t size, gfp_t flags); - /** * kmalloc_array - allocate memory for an array. * @n: number of elements. -- cgit v1.2.3-71-gd317