diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mm_types.h | 3 | ||||
| -rw-r--r-- | include/linux/slab.h | 9 |
2 files changed, 11 insertions, 1 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index faf4b7c1ad12..959cb369b197 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -130,6 +130,9 @@ struct page { struct list_head list; /* slobs list of pages */ struct slab *slab_page; /* slab fields */ + struct rcu_head rcu_head; /* Used by SLAB + * when destroying via RCU + */ }; /* Remainder is not double word aligned */ 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 */ |