[PATCH v4 28/35] mm, slab: make flush_slab() possible to call with irqs enabled

From: Vlastimil Babka
Date: Thu Aug 05 2021 - 11:25:38 EST


Currently flush_slab() is always called with disabled IRQs if it's needed, but
the following patches will change that, so add a parameter to control IRQ
disabling within the function, which only protects the kmem_cache_cpu
manipulation and not the call to deactivate_slab() which doesn't need it.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slub.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index c10f2c9b9352..dceb289cb052 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2477,16 +2477,28 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
#endif /* CONFIG_SLUB_CPU_PARTIAL */
}

-static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
+static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c,
+ bool lock)
{
- void *freelist = c->freelist;
- struct page *page = c->page;
+ unsigned long flags;
+ void *freelist;
+ struct page *page;
+
+ if (lock)
+ local_irq_save(flags);
+
+ freelist = c->freelist;
+ page = c->page;

c->page = NULL;
c->freelist = NULL;
c->tid = next_tid(c->tid);

- deactivate_slab(s, page, freelist);
+ if (lock)
+ local_irq_restore(flags);
+
+ if (page)
+ deactivate_slab(s, page, freelist);

stat(s, CPUSLAB_FLUSH);
}
@@ -2496,7 +2508,7 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);

if (c->page)
- flush_slab(s, c);
+ flush_slab(s, c, false);

unfreeze_partials_cpu(s, c);
}
@@ -2512,7 +2524,7 @@ static void flush_cpu_slab(void *d)
struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);

if (c->page)
- flush_slab(s, c);
+ flush_slab(s, c, false);

unfreeze_partials(s);
}
--
2.32.0