diff options
| -rw-r--r-- | mm/slub.c | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/mm/slub.c b/mm/slub.c index 90f0e6667130..591e41e5acc4 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -43,6 +43,7 @@ #include <linux/prefetch.h> #include <linux/memcontrol.h> #include <linux/random.h> +#include <linux/prandom.h> #include <kunit/test.h> #include <kunit/test-bug.h> #include <linux/sort.h> @@ -3311,8 +3312,11 @@ static void *next_freelist_entry(struct kmem_cache *s, return (char *)start + idx; } +static DEFINE_PER_CPU(struct rnd_state, slab_rnd_state); + /* Shuffle the single linked freelist based on a random pre-computed sequence */ -static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab) +static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab, + bool allow_spin) { void *start; void *cur; @@ -3323,7 +3327,19 @@ static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab) return false; freelist_count = oo_objects(s->oo); - pos = get_random_u32_below(freelist_count); + if (allow_spin) { + pos = get_random_u32_below(freelist_count); + } else { + struct rnd_state *state; + + /* + * An interrupt or NMI handler might interrupt and change + * the state in the middle, but that's safe. + */ + state = &get_cpu_var(slab_rnd_state); + pos = prandom_u32_state(state) % freelist_count; + put_cpu_var(slab_rnd_state); + } page_limit = slab->objects * s->size; start = fixup_red_left(s, slab_address(slab)); @@ -3350,7 +3366,8 @@ static inline int init_cache_random_seq(struct kmem_cache *s) return 0; } static inline void init_freelist_randomization(void) { } -static inline bool shuffle_freelist(struct kmem_cache *s, struct slab *slab) +static inline bool shuffle_freelist(struct kmem_cache *s, struct slab *slab, + bool allow_spin) { return false; } @@ -3441,7 +3458,7 @@ static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) alloc_slab_obj_exts_early(s, slab); account_slab(slab, oo_order(oo), s, flags); - shuffle = shuffle_freelist(s, slab); + shuffle = shuffle_freelist(s, slab, allow_spin); if (!shuffle) { start = fixup_red_left(s, start); @@ -8341,6 +8358,9 @@ void __init kmem_cache_init_late(void) { flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0); WARN_ON(!flushwq); +#ifdef CONFIG_SLAB_FREELIST_RANDOM + prandom_init_once(&slab_rnd_state); +#endif } int do_kmem_cache_create(struct kmem_cache *s, const char *name, |