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Date: Mon, 16 Sep 2019 12:11:34 -0400
From: Qian Cai <cai@....pw>
To: cl@...ux.com
Cc: penberg@...nel.org, rientjes@...gle.com, akpm@...ux-foundation.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Qian Cai <cai@....pw>
Subject: [RFC PATCH] mm/slub: remove left-over debugging code
SLUB_RESILIENCY_TEST and SLUB_DEBUG_CMPXCHG look like some left-over
debugging code during the internal development that probably nobody uses
it anymore. Remove them to make the world greener.
---
mm/slub.c | 110 --------------------------------------------------------------
1 file changed, 110 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 8834563cdb4b..f97155ba097d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -150,12 +150,6 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
* - Variable sizing of the per node arrays
*/
-/* Enable to test recovery from slab corruption on boot */
-#undef SLUB_RESILIENCY_TEST
-
-/* Enable to log cmpxchg failures */
-#undef SLUB_DEBUG_CMPXCHG
-
/*
* Mininum number of partial slabs. These will be left on the partial
* lists even if they are empty. kmem_cache_shrink may reclaim them.
@@ -392,10 +386,6 @@ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page
cpu_relax();
stat(s, CMPXCHG_DOUBLE_FAIL);
-#ifdef SLUB_DEBUG_CMPXCHG
- pr_info("%s %s: cmpxchg double redo ", n, s->name);
-#endif
-
return false;
}
@@ -433,10 +423,6 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
cpu_relax();
stat(s, CMPXCHG_DOUBLE_FAIL);
-#ifdef SLUB_DEBUG_CMPXCHG
- pr_info("%s %s: cmpxchg double redo ", n, s->name);
-#endif
-
return false;
}
@@ -2004,45 +1990,11 @@ static inline unsigned long next_tid(unsigned long tid)
return tid + TID_STEP;
}
-static inline unsigned int tid_to_cpu(unsigned long tid)
-{
- return tid % TID_STEP;
-}
-
-static inline unsigned long tid_to_event(unsigned long tid)
-{
- return tid / TID_STEP;
-}
-
static inline unsigned int init_tid(int cpu)
{
return cpu;
}
-static inline void note_cmpxchg_failure(const char *n,
- const struct kmem_cache *s, unsigned long tid)
-{
-#ifdef SLUB_DEBUG_CMPXCHG
- unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);
-
- pr_info("%s %s: cmpxchg redo ", n, s->name);
-
-#ifdef CONFIG_PREEMPT
- if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
- pr_warn("due to cpu change %d -> %d\n",
- tid_to_cpu(tid), tid_to_cpu(actual_tid));
- else
-#endif
- if (tid_to_event(tid) != tid_to_event(actual_tid))
- pr_warn("due to cpu running other code. Event %ld->%ld\n",
- tid_to_event(tid), tid_to_event(actual_tid));
- else
- pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
- actual_tid, tid, next_tid(tid));
-#endif
- stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
-}
-
static void init_kmem_cache_cpus(struct kmem_cache *s)
{
int cpu;
@@ -2751,7 +2703,6 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s,
object, tid,
next_object, next_tid(tid)))) {
- note_cmpxchg_failure("slab_alloc", s, tid);
goto redo;
}
prefetch_freepointer(s, next_object);
@@ -4694,66 +4645,6 @@ static int list_locations(struct kmem_cache *s, char *buf,
}
#endif /* CONFIG_SLUB_DEBUG */
-#ifdef SLUB_RESILIENCY_TEST
-static void __init resiliency_test(void)
-{
- u8 *p;
- int type = KMALLOC_NORMAL;
-
- BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
-
- pr_err("SLUB resiliency testing\n");
- pr_err("-----------------------\n");
- pr_err("A. Corruption after allocation\n");
-
- p = kzalloc(16, GFP_KERNEL);
- p[16] = 0x12;
- pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n",
- p + 16);
-
- validate_slab_cache(kmalloc_caches[type][4]);
-
- /* Hmmm... The next two are dangerous */
- p = kzalloc(32, GFP_KERNEL);
- p[32 + sizeof(void *)] = 0x34;
- pr_err("\n2. kmalloc-32: Clobber next pointer/next slab 0x34 -> -0x%p\n",
- p);
- pr_err("If allocated object is overwritten then not detectable\n\n");
-
- validate_slab_cache(kmalloc_caches[type][5]);
- p = kzalloc(64, GFP_KERNEL);
- p += 64 + (get_cycles() & 0xff) * sizeof(void *);
- *p = 0x56;
- pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
- p);
- pr_err("If allocated object is overwritten then not detectable\n\n");
- validate_slab_cache(kmalloc_caches[type][6]);
-
- pr_err("\nB. Corruption after free\n");
- p = kzalloc(128, GFP_KERNEL);
- kfree(p);
- *p = 0x78;
- pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
- validate_slab_cache(kmalloc_caches[type][7]);
-
- p = kzalloc(256, GFP_KERNEL);
- kfree(p);
- p[50] = 0x9a;
- pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
- validate_slab_cache(kmalloc_caches[type][8]);
-
- p = kzalloc(512, GFP_KERNEL);
- kfree(p);
- p[512] = 0xab;
- pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
- validate_slab_cache(kmalloc_caches[type][9]);
-}
-#else
-#ifdef CONFIG_SYSFS
-static void resiliency_test(void) {};
-#endif
-#endif /* SLUB_RESILIENCY_TEST */
-
#ifdef CONFIG_SYSFS
enum slab_stat_type {
SL_ALL, /* All slabs */
@@ -5875,7 +5766,6 @@ static int __init slab_sysfs_init(void)
}
mutex_unlock(&slab_mutex);
- resiliency_test();
return 0;
}
--
1.8.3.1
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