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authorLinus Torvalds <torvalds@linux-foundation.org>2013-11-22 08:10:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-11-22 08:10:34 -0800
commit24f971abbda045c24d5d6f2438a7785567d2fde9 (patch)
treea4df2b80eafa1199625b53464bcf34e786a03a28 /include/linux/slab.h
parent3bab0bf045e1cc4880e2cfc9351e52cf7ec8e35e (diff)
parent721ae22ae1a51c25871b7a0b543877aa94ff2a20 (diff)
Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux
Pull SLAB changes from Pekka Enberg: "The patches from Joonsoo Kim switch mm/slab.c to use 'struct page' for slab internals similar to mm/slub.c. This reduces memory usage and improves performance: https://lkml.org/lkml/2013/10/16/155 Rest of the changes are bug fixes from various people" * 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux: (21 commits) mm, slub: fix the typo in mm/slub.c mm, slub: fix the typo in include/linux/slub_def.h slub: Handle NULL parameter in kmem_cache_flags slab: replace non-existing 'struct freelist *' with 'void *' slab: fix to calm down kmemleak warning slub: proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled slab: rename slab_bufctl to slab_freelist slab: remove useless statement for checking pfmemalloc slab: use struct page for slab management slab: replace free and inuse in struct slab with newly introduced active slab: remove SLAB_LIMIT slab: remove kmem_bufctl_t slab: change the management method of free objects of the slab slab: use __GFP_COMP flag for allocating slab pages slab: use well-defined macro, virt_to_slab() slab: overloading the RCU head over the LRU for RCU free slab: remove cachep in struct slab_rcu slab: remove nodeid in struct slab slab: remove colouroff in struct slab slab: change return type of kmem_getpages() to struct page ...
Diffstat (limited to 'include/linux/slab.h')
-rw-r--r--include/linux/slab.h9
1 files changed, 8 insertions, 1 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 74f105847d13..c2bba248fa63 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -53,7 +53,14 @@
* }
* 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 */