On Wed, May 07, 2014 at 03:06:10PM +0900, Joonsoo Kim wrote: > This patchset does some clean-up and tries to remove lockdep annotation. > > Patches 1~3 are just for really really minor improvement. > Patches 4~10 are for clean-up and removing lockdep annotation. > > There are two cases that lockdep annotation is needed in SLAB. > 1) holding two node locks > 2) holding two array cache(alien cache) locks > > I looked at the code and found that we can avoid these cases without > any negative effect. > > 1) occurs if freeing object makes new free slab and we decide to > destroy it. Although we don't need to hold the lock during destroying > a slab, current code do that. Destroying a slab without holding the lock > would help the reduction of the lock contention. To do it, I change the > implementation that new free slab is destroyed after releasing the lock. > > 2) occurs on similar situation. When we free object from non-local node, > we put this object to alien cache with holding the alien cache lock. > If alien cache is full, we try to flush alien cache to proper node cache, > and, in this time, new free slab could be made. Destroying it would be > started and we will free metadata object which comes from another node. > In this case, we need another node's alien cache lock to free object. > This forces us to hold two array cache locks and then we need lockdep > annotation although they are always different locks and deadlock cannot > be possible. To prevent this situation, I use same way as 1). > > In this way, we can avoid 1) and 2) cases, and then, can remove lockdep > annotation. As short stat noted, this makes SLAB code much simpler. > > Many of this series get Ack from Christoph Lameter on previous iteration, > but 1, 2, 9 and 10 need to get Ack. There is no big change from previous > iteration. It is just rebased on current linux-next. > > Thanks. > > Joonsoo Kim (10): > slab: add unlikely macro to help compiler > slab: makes clear_obj_pfmemalloc() just return masked value > slab: move up code to get kmem_cache_node in free_block() > slab: defer slab_destroy in free_block() > slab: factor out initialization of arracy cache > slab: introduce alien_cache > slab: use the lock on alien_cache, instead of the lock on array_cache > slab: destroy a slab without holding any alien cache lock > slab: remove a useless lockdep annotation > slab: remove BAD_ALIEN_MAGIC > > mm/slab.c | 391 ++++++++++++++++++++++--------------------------------------- > mm/slab.h | 2 +- > 2 files changed, 140 insertions(+), 253 deletions(-) Hello, Andrew. Pekka seems to be busy. Could you manage this patchset? Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>