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From: Vlastimil Babka <vbabka@suse.cz>
Date: Thu, 29 Jul 2021 15:21:16 +0200
Subject: [PATCH 19/35] mm, slub: move reset of c->page and freelist out of
deactivate_slab()
deactivate_slab() removes the cpu slab by merging the cpu freelist with slab's
freelist and putting the slab on the proper node's list. It also sets the
respective kmem_cache_cpu pointers to NULL.
By extracting the kmem_cache_cpu operations from the function, we can make it
not dependent on disabled irqs.
Also if we return a single free pointer from ___slab_alloc, we no longer have
to assign kmem_cache_cpu.page before deactivation or care if somebody preempted
us and assigned a different page to our kmem_cache_cpu in the process.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
mm/slub.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2192,10 +2192,13 @@ static void init_kmem_cache_cpus(struct
}
/*
- * Remove the cpu slab
+ * Finishes removing the cpu slab. Merges cpu's freelist with page's freelist,
+ * unfreezes the slabs and puts it on the proper list.
+ * Assumes the slab has been already safely taken away from kmem_cache_cpu
+ * by the caller.
*/
static void deactivate_slab(struct kmem_cache *s, struct page *page,
- void *freelist, struct kmem_cache_cpu *c)
+ void *freelist)
{
enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
@@ -2324,9 +2327,6 @@ static void deactivate_slab(struct kmem_
discard_slab(s, page);
stat(s, FREE_SLAB);
}
-
- c->page = NULL;
- c->freelist = NULL;
}
/*
@@ -2451,10 +2451,16 @@ static void put_cpu_partial(struct kmem_
static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
- stat(s, CPUSLAB_FLUSH);
- deactivate_slab(s, c->page, c->freelist, c);
+ void *freelist = c->freelist;
+ struct page *page = c->page;
+ c->page = NULL;
+ c->freelist = NULL;
c->tid = next_tid(c->tid);
+
+ deactivate_slab(s, page, freelist);
+
+ stat(s, CPUSLAB_FLUSH);
}
/*
@@ -2739,7 +2745,10 @@ static void *___slab_alloc(struct kmem_c
local_irq_restore(flags);
goto reread_page;
}
- deactivate_slab(s, page, c->freelist, c);
+ freelist = c->freelist;
+ c->page = NULL;
+ c->freelist = NULL;
+ deactivate_slab(s, page, freelist);
local_irq_restore(flags);
new_slab:
@@ -2818,11 +2827,7 @@ static void *___slab_alloc(struct kmem_c
return_single:
local_irq_save(flags);
- if (unlikely(c->page))
- flush_slab(s, c);
- c->page = page;
-
- deactivate_slab(s, page, get_freepointer(s, freelist), c);
+ deactivate_slab(s, page, get_freepointer(s, freelist));
local_irq_restore(flags);
return freelist;
}
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