[RFC v2 05/34] mm, slub: remove redundant unfreeze_partials() from put_cpu_partial()

From: Vlastimil Babka
Date: Wed Jun 09 2021 - 07:39:37 EST

Commit d6e0b7fa1186 ("slub: make dead caches discard free slabs immediately")
introduced cpu partial flushing for kmemcg caches, based on setting the target
cpu_partial to 0 and adding a flushing check in put_cpu_partial().
This code that sets cpu_partial to 0 was later moved by c9fc586403e7 ("slab:
introduce __kmemcg_cache_deactivate()") and ultimately removed by 9855609bde03
("mm: memcg/slab: use a single set of kmem_caches for all accounted
allocations"). However the check and flush in put_cpu_partial() was never
removed, although it's effectively a dead code. So this patch removes it.

Note that d6e0b7fa1186 also added preempt_disable()/enable() to
unfreeze_partials() which could be thus also considered unnecessary. But
further patches will rely on it, so keep it.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
mm/slub.c | 7 -------
1 file changed, 7 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 2953f6e43cae..f740598696b4 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2420,13 +2420,6 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)

} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page)
!= oldpage);
- if (unlikely(!slub_cpu_partial(s))) {
- unsigned long flags;
- local_irq_save(flags);
- unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
- local_irq_restore(flags);
- }