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@xxxxxx>
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slub.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index c4a9b8901576..fa9a366d2d9c 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2511,9 +2511,17 @@ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
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);
}
--
2.33.0
