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-rw-r--r--mm/migrate.c15
-rw-r--r--mm/slab.c6
-rw-r--r--mm/slab.h54
-rw-r--r--mm/slub.c26
4 files changed, 64 insertions, 37 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 1379e1912772..959c99cff814 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -74,13 +74,22 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
if (unlikely(!get_page_unless_zero(page)))
goto out;
+ if (unlikely(PageSlab(page)))
+ goto out_putpage;
+ /* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */
+ smp_rmb();
/*
- * Check PageMovable before holding a PG_lock because page's owner
- * assumes anybody doesn't touch PG_lock of newly allocated page
- * so unconditionally grabbing the lock ruins page's owner side.
+ * Check movable flag before taking the page lock because
+ * we use non-atomic bitops on newly allocated page flags so
+ * unconditionally grabbing the lock ruins page's owner side.
*/
if (unlikely(!__PageMovable(page)))
goto out_putpage;
+ /* Pairs with smp_wmb() in slab allocation, e.g. SLUB's alloc_slab_page() */
+ smp_rmb();
+ if (unlikely(PageSlab(page)))
+ goto out_putpage;
+
/*
* As movable pages are not isolated from LRU lists, concurrent
* compaction threads can race against page migration functions
diff --git a/mm/slab.c b/mm/slab.c
index a9a6592e5e31..cbee5bbc6f11 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1370,6 +1370,8 @@ static struct slab *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
account_slab(slab, cachep->gfporder, cachep, flags);
__folio_set_slab(folio);
+ /* Make the flag visible before any changes to folio->mapping */
+ smp_wmb();
/* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
if (sk_memalloc_socks() && page_is_pfmemalloc(folio_page(folio, 0)))
slab_set_pfmemalloc(slab);
@@ -1387,9 +1389,11 @@ static void kmem_freepages(struct kmem_cache *cachep, struct slab *slab)
BUG_ON(!folio_test_slab(folio));
__slab_clear_pfmemalloc(slab);
- __folio_clear_slab(folio);
page_mapcount_reset(folio_page(folio, 0));
folio->mapping = NULL;
+ /* Make the mapping reset visible before clearing the flag */
+ smp_wmb();
+ __folio_clear_slab(folio);
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += 1 << order;
diff --git a/mm/slab.h b/mm/slab.h
index 19e1baac807c..8c4aafb00bd6 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -11,37 +11,43 @@ struct slab {
#if defined(CONFIG_SLAB)
+ struct kmem_cache *slab_cache;
union {
- struct list_head slab_list;
+ struct {
+ struct list_head slab_list;
+ void *freelist; /* array of free object indexes */
+ void *s_mem; /* first object */
+ };
struct rcu_head rcu_head;
};
- struct kmem_cache *slab_cache;
- void *freelist; /* array of free object indexes */
- void *s_mem; /* first object */
unsigned int active;
#elif defined(CONFIG_SLUB)
- union {
- struct list_head slab_list;
- struct rcu_head rcu_head;
-#ifdef CONFIG_SLUB_CPU_PARTIAL
- struct {
- struct slab *next;
- int slabs; /* Nr of slabs left */
- };
-#endif
- };
struct kmem_cache *slab_cache;
- /* Double-word boundary */
- void *freelist; /* first free object */
union {
- unsigned long counters;
struct {
- unsigned inuse:16;
- unsigned objects:15;
- unsigned frozen:1;
+ union {
+ struct list_head slab_list;
+#ifdef CONFIG_SLUB_CPU_PARTIAL
+ struct {
+ struct slab *next;
+ int slabs; /* Nr of slabs left */
+ };
+#endif
+ };
+ /* Double-word boundary */
+ void *freelist; /* first free object */
+ union {
+ unsigned long counters;
+ struct {
+ unsigned inuse:16;
+ unsigned objects:15;
+ unsigned frozen:1;
+ };
+ };
};
+ struct rcu_head rcu_head;
};
unsigned int __unused;
@@ -66,9 +72,10 @@ struct slab {
#define SLAB_MATCH(pg, sl) \
static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl))
SLAB_MATCH(flags, __page_flags);
-SLAB_MATCH(compound_head, slab_list); /* Ensure bit 0 is clear */
#ifndef CONFIG_SLOB
-SLAB_MATCH(rcu_head, rcu_head);
+SLAB_MATCH(compound_head, slab_cache); /* Ensure bit 0 is clear */
+#else
+SLAB_MATCH(compound_head, slab_list); /* Ensure bit 0 is clear */
#endif
SLAB_MATCH(_refcount, __page_refcount);
#ifdef CONFIG_MEMCG
@@ -76,6 +83,9 @@ SLAB_MATCH(memcg_data, memcg_data);
#endif
#undef SLAB_MATCH
static_assert(sizeof(struct slab) <= sizeof(struct page));
+#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && defined(CONFIG_SLUB)
+static_assert(IS_ALIGNED(offsetof(struct slab, freelist), 2*sizeof(void *)));
+#endif
/**
* folio_slab - Converts from folio to slab.
diff --git a/mm/slub.c b/mm/slub.c
index 1ff5319c0ea8..0a14e7bc278c 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1800,6 +1800,8 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node,
slab = folio_slab(folio);
__folio_set_slab(folio);
+ /* Make the flag visible before any changes to folio->mapping */
+ smp_wmb();
if (page_is_pfmemalloc(folio_page(folio, 0)))
slab_set_pfmemalloc(slab);
@@ -1999,17 +2001,11 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab)
int order = folio_order(folio);
int pages = 1 << order;
- if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
- void *p;
-
- slab_pad_check(s, slab);
- for_each_object(p, s, slab_address(slab), slab->objects)
- check_object(s, slab, p, SLUB_RED_INACTIVE);
- }
-
__slab_clear_pfmemalloc(slab);
- __folio_clear_slab(folio);
folio->mapping = NULL;
+ /* Make the mapping reset visible before clearing the flag */
+ smp_wmb();
+ __folio_clear_slab(folio);
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += pages;
unaccount_slab(slab, order, s);
@@ -2025,9 +2021,17 @@ static void rcu_free_slab(struct rcu_head *h)
static void free_slab(struct kmem_cache *s, struct slab *slab)
{
- if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
+ if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
+ void *p;
+
+ slab_pad_check(s, slab);
+ for_each_object(p, s, slab_address(slab), slab->objects)
+ check_object(s, slab, p, SLUB_RED_INACTIVE);
+ }
+
+ if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU))
call_rcu(&slab->rcu_head, rcu_free_slab);
- } else
+ else
__free_slab(s, slab);
}
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-24 08:51:38 +0300