[PATCH 05/30] mm: slb: add knowledge of reserve pages
From: Peter Zijlstra
Date: Thu Jul 24 2008 - 10:43:17 EST
Restrict objects from reserve slabs (ALLOC_NO_WATERMARKS) to allocation
contexts that are entitled to it. This is done to ensure reserve pages don't
leak out and get consumed.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
include/linux/slub_def.h | 1
mm/slab.c | 60 +++++++++++++++++++++++++++++++++++++++--------
mm/slub.c | 28 ++++++++++++++++++---
3 files changed, 75 insertions(+), 14 deletions(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -23,6 +23,7 @@
#include <linux/kallsyms.h>
#include <linux/memory.h>
#include <linux/math64.h>
+#include "internal.h"
/*
* Lock order:
@@ -1106,7 +1107,8 @@ static void setup_object(struct kmem_cac
s->ctor(s, object);
}
-static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
+static
+struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node, int *reserve)
{
struct page *page;
void *start;
@@ -1120,6 +1122,8 @@ static struct page *new_slab(struct kmem
if (!page)
goto out;
+ *reserve = page->reserve;
+
inc_slabs_node(s, page_to_nid(page), page->objects);
page->slab = s;
page->flags |= 1 << PG_slab;
@@ -1509,10 +1513,20 @@ static void *__slab_alloc(struct kmem_ca
{
void **object;
struct page *new;
+ int reserve;
/* We handle __GFP_ZERO in the caller */
gfpflags &= ~__GFP_ZERO;
+ if (unlikely(c->reserve)) {
+ /*
+ * If the current slab is a reserve slab and the current
+ * allocation context does not allow access to the reserves we
+ * must force an allocation to test the current levels.
+ */
+ if (!(gfp_to_alloc_flags(gfpflags) & ALLOC_NO_WATERMARKS))
+ goto grow_slab;
+ }
if (!c->page)
goto new_slab;
@@ -1526,7 +1540,7 @@ load_freelist:
object = c->page->freelist;
if (unlikely(!object))
goto another_slab;
- if (unlikely(SLABDEBUG && PageSlubDebug(c->page)))
+ if (unlikely(PageSlubDebug(c->page) || c->reserve))
goto debug;
c->freelist = object[c->offset];
@@ -1549,16 +1563,18 @@ new_slab:
goto load_freelist;
}
+grow_slab:
if (gfpflags & __GFP_WAIT)
local_irq_enable();
- new = new_slab(s, gfpflags, node);
+ new = new_slab(s, gfpflags, node, &reserve);
if (gfpflags & __GFP_WAIT)
local_irq_disable();
if (new) {
c = get_cpu_slab(s, smp_processor_id());
+ c->reserve = reserve;
stat(c, ALLOC_SLAB);
if (c->page)
flush_slab(s, c);
@@ -1569,7 +1585,8 @@ new_slab:
}
return NULL;
debug:
- if (!alloc_debug_processing(s, c->page, object, addr))
+ if (PageSlubDebug(c->page) &&
+ !alloc_debug_processing(s, c->page, object, addr))
goto another_slab;
c->page->inuse++;
@@ -2068,10 +2085,11 @@ static struct kmem_cache_node *early_kme
struct page *page;
struct kmem_cache_node *n;
unsigned long flags;
+ int reserve;
BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
- page = new_slab(kmalloc_caches, gfpflags, node);
+ page = new_slab(kmalloc_caches, gfpflags, node, &reserve);
BUG_ON(!page);
if (page_to_nid(page) != node) {
Index: linux-2.6/include/linux/slub_def.h
===================================================================
--- linux-2.6.orig/include/linux/slub_def.h
+++ linux-2.6/include/linux/slub_def.h
@@ -38,6 +38,7 @@ struct kmem_cache_cpu {
int node; /* The node of the page (or -1 for debug) */
unsigned int offset; /* Freepointer offset (in word units) */
unsigned int objsize; /* Size of an object (from kmem_cache) */
+ int reserve; /* Did the current page come from the reserve */
#ifdef CONFIG_SLUB_STATS
unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c
+++ linux-2.6/mm/slab.c
@@ -116,6 +116,8 @@
#include <asm/tlbflush.h>
#include <asm/page.h>
+#include "internal.h"
+
/*
* DEBUG - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
* 0 for faster, smaller code (especially in the critical paths).
@@ -265,7 +267,8 @@ struct array_cache {
unsigned int avail;
unsigned int limit;
unsigned int batchcount;
- unsigned int touched;
+ unsigned int touched:1,
+ reserve:1;
spinlock_t lock;
void *entry[]; /*
* Must have this definition in here for the proper
@@ -761,6 +764,27 @@ static inline struct array_cache *cpu_ca
return cachep->array[smp_processor_id()];
}
+/*
+ * If the last page came from the reserves, and the current allocation context
+ * does not have access to them, force an allocation to test the watermarks.
+ */
+static inline int slab_force_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+ if (unlikely(cpu_cache_get(cachep)->reserve) &&
+ !(gfp_to_alloc_flags(flags) & ALLOC_NO_WATERMARKS))
+ return 1;
+
+ return 0;
+}
+
+static inline void slab_set_reserve(struct kmem_cache *cachep, int reserve)
+{
+ struct array_cache *ac = cpu_cache_get(cachep);
+
+ if (unlikely(ac->reserve != reserve))
+ ac->reserve = reserve;
+}
+
static inline struct kmem_cache *__find_general_cachep(size_t size,
gfp_t gfpflags)
{
@@ -960,6 +984,7 @@ static struct array_cache *alloc_arrayca
nc->limit = entries;
nc->batchcount = batchcount;
nc->touched = 0;
+ nc->reserve = 0;
spin_lock_init(&nc->lock);
}
return nc;
@@ -1662,7 +1687,8 @@ __initcall(cpucache_init);
* did not request dmaable memory, we might get it, but that
* would be relatively rare and ignorable.
*/
-static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
+static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid,
+ int *reserve)
{
struct page *page;
int nr_pages;
@@ -1684,6 +1710,7 @@ static void *kmem_getpages(struct kmem_c
if (!page)
return NULL;
+ *reserve = page->reserve;
nr_pages = (1 << cachep->gfporder);
if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
add_zone_page_state(page_zone(page),
@@ -2112,6 +2139,7 @@ static int __init_refok setup_cpu_cache(
cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
cpu_cache_get(cachep)->batchcount = 1;
cpu_cache_get(cachep)->touched = 0;
+ cpu_cache_get(cachep)->reserve = 0;
cachep->batchcount = 1;
cachep->limit = BOOT_CPUCACHE_ENTRIES;
return 0;
@@ -2767,6 +2795,7 @@ static int cache_grow(struct kmem_cache
size_t offset;
gfp_t local_flags;
struct kmem_list3 *l3;
+ int reserve;
/*
* Be lazy and only check for valid flags here, keeping it out of the
@@ -2805,7 +2834,7 @@ static int cache_grow(struct kmem_cache
* 'nodeid'.
*/
if (!objp)
- objp = kmem_getpages(cachep, local_flags, nodeid);
+ objp = kmem_getpages(cachep, local_flags, nodeid, &reserve);
if (!objp)
goto failed;
@@ -2822,6 +2851,7 @@ static int cache_grow(struct kmem_cache
if (local_flags & __GFP_WAIT)
local_irq_disable();
check_irq_off();
+ slab_set_reserve(cachep, reserve);
spin_lock(&l3->list_lock);
/* Make slab active. */
@@ -2967,7 +2997,8 @@ bad:
#define check_slabp(x,y) do { } while(0)
#endif
-static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
+static void *cache_alloc_refill(struct kmem_cache *cachep,
+ gfp_t flags, int must_refill)
{
int batchcount;
struct kmem_list3 *l3;
@@ -2977,6 +3008,8 @@ static void *cache_alloc_refill(struct k
retry:
check_irq_off();
node = numa_node_id();
+ if (unlikely(must_refill))
+ goto force_grow;
ac = cpu_cache_get(cachep);
batchcount = ac->batchcount;
if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
@@ -3044,11 +3077,14 @@ alloc_done:
if (unlikely(!ac->avail)) {
int x;
+force_grow:
x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL);
/* cache_grow can reenable interrupts, then ac could change. */
ac = cpu_cache_get(cachep);
- if (!x && ac->avail == 0) /* no objects in sight? abort */
+
+ /* no objects in sight? abort */
+ if (!x && (ac->avail == 0 || must_refill))
return NULL;
if (!ac->avail) /* objects refilled by interrupt? */
@@ -3203,17 +3239,18 @@ static inline void *____cache_alloc(stru
{
void *objp;
struct array_cache *ac;
+ int must_refill = slab_force_alloc(cachep, flags);
check_irq_off();
ac = cpu_cache_get(cachep);
- if (likely(ac->avail)) {
+ if (likely(ac->avail && !must_refill)) {
STATS_INC_ALLOCHIT(cachep);
ac->touched = 1;
objp = ac->entry[--ac->avail];
} else {
STATS_INC_ALLOCMISS(cachep);
- objp = cache_alloc_refill(cachep, flags);
+ objp = cache_alloc_refill(cachep, flags, must_refill);
}
return objp;
}
@@ -3257,7 +3294,7 @@ static void *fallback_alloc(struct kmem_
struct zone *zone;
enum zone_type high_zoneidx = gfp_zone(flags);
void *obj = NULL;
- int nid;
+ int nid, reserve;
if (flags & __GFP_THISNODE)
return NULL;
@@ -3293,10 +3330,11 @@ retry:
if (local_flags & __GFP_WAIT)
local_irq_enable();
kmem_flagcheck(cache, flags);
- obj = kmem_getpages(cache, local_flags, -1);
+ obj = kmem_getpages(cache, local_flags, -1, &reserve);
if (local_flags & __GFP_WAIT)
local_irq_disable();
if (obj) {
+ slab_set_reserve(cache, reserve);
/*
* Insert into the appropriate per node queues
*/
@@ -3335,6 +3373,9 @@ static void *____cache_alloc_node(struct
l3 = cachep->nodelists[nodeid];
BUG_ON(!l3);
+ if (unlikely(slab_force_alloc(cachep, flags)))
+ goto force_grow;
+
retry:
check_irq_off();
spin_lock(&l3->list_lock);
@@ -3372,6 +3413,7 @@ retry:
must_grow:
spin_unlock(&l3->list_lock);
+force_grow:
x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL);
if (x)
goto retry;
--
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/