On Mon, Jun 22, 2020 at 10:40 AM Roman Gushchin <guro@xxxxxx> wrote: > > On Mon, Jun 22, 2020 at 10:29:29AM -0700, Shakeel Butt wrote: > > On Mon, Jun 8, 2020 at 4:07 PM Roman Gushchin <guro@xxxxxx> wrote: > > > > > > Because the number of non-root kmem_caches doesn't depend on the > > > number of memory cgroups anymore and is generally not very big, > > > there is no more need for a dedicated workqueue. > > > > > > Also, as there is no more need to pass any arguments to the > > > memcg_create_kmem_cache() except the root kmem_cache, it's > > > possible to just embed the work structure into the kmem_cache > > > and avoid the dynamic allocation of the work structure. > > > > > > This will also simplify the synchronization: for each root kmem_cache > > > there is only one work. So there will be no more concurrent attempts > > > to create a non-root kmem_cache for a root kmem_cache: the second and > > > all following attempts to queue the work will fail. > > > > > > > > > On the kmem_cache destruction path there is no more need to call the > > > expensive flush_workqueue() and wait for all pending works to be > > > finished. Instead, cancel_work_sync() can be used to cancel/wait for > > > only one work. > > > > > > Signed-off-by: Roman Gushchin <guro@xxxxxx> > > > Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> > > > > Why not pre-allocate the non-root kmem_cache at the kmem_cache > > creation time? No need for work_struct, queue_work() or > > cancel_work_sync() at all. > > Simple because some kmem_caches are created very early, so we don't > even know at that time if we will need memcg slab caches. But this > code is likely going away if we're going with a single set for all > allocations. > LGTM. Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
