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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-01-18 02:53:44 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-04-18 11:42:36 -0700
commit5f0d5a3ae7cff0d7fa943c199c3a2e44f23e1fac (patch)
treeb7ba2116923723e193dfe7c633ec10056c6b1b53 /kernel
parent4495c08e84729385774601b5146d51d9e5849f81 (diff)
downloadop-kernel-dev-5f0d5a3ae7cff0d7fa943c199c3a2e44f23e1fac.zip
op-kernel-dev-5f0d5a3ae7cff0d7fa943c199c3a2e44f23e1fac.tar.gz
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 <paulmck@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <linux-mm@kvack.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> [ 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 <rientjes@google.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c4
-rw-r--r--kernel/signal.c2
2 files changed, 3 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 6c463c80..9330ce2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1313,7 +1313,7 @@ void __cleanup_sighand(struct sighand_struct *sighand)
if (atomic_dec_and_test(&sighand->count)) {
signalfd_cleanup(sighand);
/*
- * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
+ * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
* without an RCU grace period, see __lock_task_sighand().
*/
kmem_cache_free(sighand_cachep, sighand);
@@ -2144,7 +2144,7 @@ void __init proc_caches_init(void)
{
sighand_cachep = kmem_cache_create("sighand_cache",
sizeof(struct sighand_struct), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
SLAB_NOTRACK|SLAB_ACCOUNT, sighand_ctor);
signal_cachep = kmem_cache_create("signal_cache",
sizeof(struct signal_struct), 0,
diff --git a/kernel/signal.c b/kernel/signal.c
index 7e59ebc..6df5f72 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1237,7 +1237,7 @@ struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
}
/*
* This sighand can be already freed and even reused, but
- * we rely on SLAB_DESTROY_BY_RCU and sighand_ctor() which
+ * we rely on SLAB_TYPESAFE_BY_RCU and sighand_ctor() which
* initializes ->siglock: this slab can't go away, it has
* the same object type, ->siglock can't be reinitialized.
*
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