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From: Vlastimil Babka <vbabka@suse.cz>
Date: Thu, 3 Jun 2021 19:17:42 +0200
Subject: [PATCH 27/33] mm, slab: split out the cpu offline variant of
flush_slab()
flush_slab() is called either as part IPI handler on given live cpu, or as a
cleanup on behalf of another cpu that went offline. The first case needs to
protect updating the kmem_cache_cpu fields with disabled irqs. Currently the
whole call happens with irqs disabled by the IPI handler, but the following
patch will change from IPI to workqueue, and flush_slab() will have to disable
irqs (to be replaced with a local lock later) in the critical part.
To prepare for this change, replace the call to flush_slab() for the dead cpu
handling with an opencoded variant that will not disable irqs nor take a local
lock.
Suggested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/slub.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2511,9 +2511,17 @@ static inline void flush_slab(struct kme
static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+ void *freelist = c->freelist;
+ struct page *page = c->page;
- if (c->page)
- flush_slab(s, c);
+ c->page = NULL;
+ c->freelist = NULL;
+ c->tid = next_tid(c->tid);
+
+ if (page) {
+ deactivate_slab(s, page, freelist);
+ stat(s, CPUSLAB_FLUSH);
+ }
unfreeze_partials_cpu(s, c);
}
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