From 5f0d5a3ae7cff0d7fa943c199c3a2e44f23e1fac Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 18 Jan 2017 02:53:44 -0800 Subject: mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU A group of Linux kernel hackers reported chasing a bug that resulted from their assumption that SLAB_DESTROY_BY_RCU provided an existence guarantee, that is, that no block from such a slab would be reallocated during an RCU read-side critical section. Of course, that is not the case. Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire slab of blocks. However, there is a phrase for this, namely "type safety". This commit therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order to avoid future instances of this sort of confusion. Signed-off-by: Paul E. McKenney Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrew Morton Cc: Acked-by: Johannes Weiner Acked-by: Vlastimil Babka [ paulmck: Add comments mentioning the old name, as requested by Eric Dumazet, in order to help people familiar with the old name find the new one. ] Acked-by: David Rientjes --- mm/slab_common.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/slab_common.c') diff --git a/mm/slab_common.c b/mm/slab_common.c index 09d0e849b07f..01a0fe2eb332 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -39,7 +39,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work, * Set of flags that will prevent slab merging */ #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ - SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \ + SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ SLAB_FAILSLAB | SLAB_KASAN) #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ @@ -500,7 +500,7 @@ static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) struct kmem_cache *s, *s2; /* - * On destruction, SLAB_DESTROY_BY_RCU kmem_caches are put on the + * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the * @slab_caches_to_rcu_destroy list. The slab pages are freed * through RCU and and the associated kmem_cache are dereferenced * while freeing the pages, so the kmem_caches should be freed only @@ -537,7 +537,7 @@ static int shutdown_cache(struct kmem_cache *s) memcg_unlink_cache(s); list_del(&s->list); - if (s->flags & SLAB_DESTROY_BY_RCU) { + if (s->flags & SLAB_TYPESAFE_BY_RCU) { list_add_tail(&s->list, &slab_caches_to_rcu_destroy); schedule_work(&slab_caches_to_rcu_destroy_work); } else { -- cgit v1.2.3-59-g8ed1b