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 --- fs/jbd2/journal.c | 2 +- fs/signalfd.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'fs') diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index a1a359bfcc9c..7f8f962454e5 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -2340,7 +2340,7 @@ static int jbd2_journal_init_journal_head_cache(void) jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head", sizeof(struct journal_head), 0, /* offset */ - SLAB_TEMPORARY | SLAB_DESTROY_BY_RCU, + SLAB_TEMPORARY | SLAB_TYPESAFE_BY_RCU, NULL); /* ctor */ retval = 0; if (!jbd2_journal_head_cache) { diff --git a/fs/signalfd.c b/fs/signalfd.c index 270221fcef42..7e3d71109f51 100644 --- a/fs/signalfd.c +++ b/fs/signalfd.c @@ -38,7 +38,7 @@ void signalfd_cleanup(struct sighand_struct *sighand) /* * The lockless check can race with remove_wait_queue() in progress, * but in this case its caller should run under rcu_read_lock() and - * sighand_cachep is SLAB_DESTROY_BY_RCU, we can safely return. + * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return. */ if (likely(!waitqueue_active(wqh))) return; -- cgit v1.2.3-59-g8ed1b