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linux-uek4-mm.patch
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From af0ab2d922beac827bc9ba06a9f67fccf0b13fa8 Mon Sep 17 00:00:00 2001
From: Dongli Zhang <[email protected]>
Date: Tue, 28 Jan 2020 16:23:07 -0800
Subject: [PATCH 1/1] linux uek4 mm
v4.1.12-124.24.3
Signed-off-by: Dongli Zhang <[email protected]>
---
include/linux/poison.h | 2 +
mm/slab.h | 5 +
mm/slub.c | 682 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 689 insertions(+)
diff --git a/include/linux/poison.h b/include/linux/poison.h
index 253c9b4198ef..e338a5c4ccec 100644
--- a/include/linux/poison.h
+++ b/include/linux/poison.h
@@ -44,7 +44,9 @@
#define SLUB_RED_ACTIVE 0xcc
/* ...and for poisoning */
+/* Z */
#define POISON_INUSE 0x5a /* for use-uninitialised poisoning */
+/* k */
#define POISON_FREE 0x6b /* for use-after-free poisoning */
#define POISON_END 0xa5 /* end-byte of poisoning */
diff --git a/mm/slab.h b/mm/slab.h
index 4c3ac12dd644..74ac22a49c7c 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -299,6 +299,11 @@ static inline void slab_init_memcg_params(struct kmem_cache *s)
}
#endif /* CONFIG_MEMCG_KMEM */
+/*
+ * called by:
+ * - mm/slab.c|3554| <<kmem_cache_free>> cachep = cache_from_obj(cachep, objp);
+ * - mm/slub.c|2955| <<kmem_cache_free>> s = cache_from_obj(s, x);
+ */
static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
{
struct kmem_cache *cachep;
diff --git a/mm/slub.c b/mm/slub.c
index 3d7932cc7084..b9f2142aaa1e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -115,15 +115,55 @@
* the fast path and disables lockless freelists.
*/
+ /*
+ * called by:
+ * - mm/slub.c|130| <<kmem_cache_has_cpu_partial>> return !kmem_cache_debug(s);
+ * - mm/slub.c|1549| <<__free_slab>> if (kmem_cache_debug(s)) {
+ * - mm/slub.c|2004| <<deactivate_slab>> if (kmem_cache_debug(s) && !lock) {
+ * - mm/slub.c|2507| <<__slab_alloc>> if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags)))
+ * - mm/slub.c|2511| <<__slab_alloc>> if (kmem_cache_debug(s) &&
+ * - mm/slub.c|2697| <<__slab_free>> if (kmem_cache_debug(s) &&
+ * - mm/slub.c|2772| <<__slab_free>> if (kmem_cache_debug(s))
+ *
+ * 判断kmem_cache->flags是否有SLAB_DEBUG_FLAGS包含的以下:
+ * - SLAB_RED_ZONE
+ * - SLAB_POISON
+ * - SLAB_STORE_USER
+ * - SLAB_TRACE
+ * - SLAB_DEBUG_FREE
+ */
static inline int kmem_cache_debug(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_DEBUG
+ /*
+ * SLAB_DEBUG_FLAGS包含以下:
+ * - SLAB_RED_ZONE
+ * - SLAB_POISON
+ * - SLAB_STORE_USER
+ * - SLAB_TRACE
+ * - SLAB_DEBUG_FREE
+ */
return unlikely(s->flags & SLAB_DEBUG_FLAGS);
#else
return 0;
#endif
}
+/*
+ * called by:
+ * - mm/slub.c|1742| <<get_partial_node>> if (!kmem_cache_has_cpu_partial(s)
+ * - mm/slub.c|2714| <<__slab_free>> if (kmem_cache_has_cpu_partial(s) && !prior) {
+ * - mm/slub.c|2771| <<__slab_free>> if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
+ * - mm/slub.c|3279| <<kmem_cache_open>> if (!kmem_cache_has_cpu_partial(s))
+ * - mm/slub.c|4575| <<cpu_partial_store>> if (objects && !kmem_cache_has_cpu_partial(s))
+ *
+ * 如果kmem_cache->flags设置了SLAB_DEBUG_FLAGS中的以下任何则返回false:
+ * - SLAB_RED_ZONE
+ * - SLAB_POISON
+ * - SLAB_STORE_USER
+ * - SLAB_TRACE
+ * - SLAB_DEBUG_FREE
+ */
static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
@@ -225,6 +265,16 @@ static inline void stat(const struct kmem_cache *s, enum stat_item si)
*******************************************************************/
/* Verify that a pointer has an address that is valid within a slab page */
+/*
+ * called by:
+ * - mm/slub.c|850| <<check_object>> if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+ * - mm/slub.c|905| <<on_freelist>> if (!check_valid_pointer(s, page, fp)) {
+ * - mm/slub.c|1037| <<alloc_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ * - mm/slub.c|1078| <<free_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ *
+ * 查看object的地址是否在page的slab的范围内
+ * 如果在返回1, 否则返回0
+ */
static inline int check_valid_pointer(struct kmem_cache *s,
struct page *page, const void *object)
{
@@ -242,6 +292,18 @@ static inline int check_valid_pointer(struct kmem_cache *s,
return 1;
}
+/*
+ * called by:
+ * - mm/slub.c|262| <<get_freepointer_safe>> p = get_freepointer(s, object);
+ * - mm/slub.c|455| <<get_map>> for (p = page->freelist; p; p = get_freepointer(s, p))
+ * - mm/slub.c|627| <<print_trailer>> p, p - addr, get_freepointer(s, p));
+ * - mm/slub.c|850| <<check_object>> if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+ * - mm/slub.c|920| <<on_freelist>> fp = get_freepointer(s, object);
+ * - mm/slub.c|1843| <<deactivate_slab>> while (freelist && (nextfree = get_freepointer(s, freelist))) {
+ * - mm/slub.c|2377| <<__slab_alloc>> c->freelist = get_freepointer(s, freelist);
+ * - mm/slub.c|2409| <<__slab_alloc>> deactivate_slab(s, page, get_freepointer(s, freelist));
+ * - mm/slub.c|2942| <<early_kmem_cache_node_alloc>> page->freelist = get_freepointer(kmem_cache_node, n);
+ */
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
return *(void **)(object + s->offset);
@@ -252,6 +314,10 @@ static void prefetch_freepointer(const struct kmem_cache *s, void *object)
prefetch(object + s->offset);
}
+/*
+ * called by:
+ * - mm/slub.c|2477| <<slab_alloc_node>> void *next_object = get_freepointer_safe(s, object);
+ */
static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
{
void *p;
@@ -264,6 +330,17 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
return p;
}
+/*
+ * called by:
+ * - mm/slub.c|857| <<check_object>> set_freepointer(s, p, NULL);
+ * - mm/slub.c|909| <<on_freelist>> set_freepointer(s, object, NULL);
+ * - mm/slub.c|1444| <<new_slab>> set_freepointer(s, p, p + s->size);
+ * - mm/slub.c|1446| <<new_slab>> set_freepointer(s, p, NULL);
+ * - mm/slub.c|1850| <<deactivate_slab>> set_freepointer(s, freelist, prior);
+ * - mm/slub.c|1887| <<deactivate_slab>> set_freepointer(s, freelist, old.freelist);
+ * - mm/slub.c|2602| <<__slab_free>> set_freepointer(s, object, prior);
+ * - mm/slub.c|2728| <<slab_free>> set_freepointer(s, object, c->freelist);
+ */
static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
*(void **)(object + s->offset) = fp;
@@ -279,11 +356,24 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
__p += (__s)->size, __idx++)
/* Determine object index from a given position */
+/*
+ * called by:
+ * - mm/slub.c|456| <<get_map>> set_bit(slab_index(p, s, addr), map);
+ * - mm/slub.c|3219| <<list_slab_objects>> if (!test_bit(slab_index(p, s, addr), map)) {
+ * - mm/slub.c|3889| <<validate_slab>> if (test_bit(slab_index(p, s, addr), map))
+ * - mm/slub.c|3895| <<validate_slab>> if (!test_bit(slab_index(p, s, addr), map))
+ * - mm/slub.c|4096| <<process_slab>> if (!test_bit(slab_index(p, s, addr), map))
+ */
static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
{
return (p - addr) / s->size;
}
+/*
+ * called by:
+ * - mm/slub.c|1320| <<slab_post_alloc_hook>> kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
+ * - mm/slub.c|3431| <<__ksize>> return slab_ksize(page->slab_cache);
+ */
static inline size_t slab_ksize(const struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_DEBUG
@@ -308,11 +398,24 @@ static inline size_t slab_ksize(const struct kmem_cache *s)
return s->size;
}
+/*
+ * called by:
+ * - mm/slub.c|362| <<oo_make>> (order << OO_SHIFT) + order_objects(order, size, reserved)
+ * - mm/slub.c|916| <<check_slab>> maxobj = order_objects(compound_order(page), s->size, s->reserved);
+ * - mm/slub.c|966| <<on_freelist>> max_objects = order_objects(compound_order(page), s->size, s->reserved);
+ * - mm/slub.c|2851| <<slab_order>> if (order_objects(min_order, size, reserved) > MAX_OBJS_PER_PAGE)
+ * - mm/slub.c|2891| <<calculate_order>> max_objects = order_objects(slub_max_order, size, reserved);
+ */
static inline int order_objects(int order, unsigned long size, int reserved)
{
return ((PAGE_SIZE << order) - reserved) / size;
}
+/*
+ * called by:
+ * - mm/slub.c|3154| <<calculate_sizes>> s->oo = oo_make(order, size, s->reserved);
+ * - mm/slub.c|3155| <<calculate_sizes>> s->min = oo_make(get_order(size), size, s->reserved);
+ */
static inline struct kmem_cache_order_objects oo_make(int order,
unsigned long size, int reserved)
{
@@ -323,11 +426,34 @@ static inline struct kmem_cache_order_objects oo_make(int order,
return x;
}
+/*
+ * called by:
+ * - mm/slub.c|1358| <<alloc_slab_page>> int order = oo_order(oo);
+ * - mm/slub.c|1412| <<allocate_slab>> int pages = 1 << oo_order(oo);
+ * - mm/slub.c|1414| <<allocate_slab>> kmemcheck_alloc_shadow(page, oo_order(oo), alloc_gfp, node);
+ * - mm/slub.c|1435| <<allocate_slab>> 1 << oo_order(oo));
+ * - mm/slub.c|2234| <<slab_out_of_memory>> s->name, s->object_size, s->size, oo_order(s->oo),
+ * - mm/slub.c|2235| <<slab_out_of_memory>> oo_order(s->min));
+ * - mm/slub.c|2237| <<slab_out_of_memory>> if (oo_order(s->min) > get_order(s->object_size))
+ * - mm/slub.c|3241| <<kmem_cache_open>> oo_order(s->oo), s->offset, flags);
+ * - mm/slub.c|4473| <<order_show>> return sprintf(buf, "%d\n", oo_order(s->oo));
+ * - mm/slub.c|5375| <<get_slabinfo>> sinfo->cache_order = oo_order(s->oo);
+ */
static inline int oo_order(struct kmem_cache_order_objects x)
{
return x.x >> OO_SHIFT;
}
+/*
+ * called by:
+ * - mm/slub.c|1431| <<allocate_slab>> page->objects = oo_objects(oo);
+ * - mm/slub.c|3156| <<calculate_sizes>> if (oo_objects(s->oo) > oo_objects(s->max))
+ * - mm/slub.c|3159| <<calculate_sizes>> return !!oo_objects(s->oo);
+ * - mm/slub.c|3988| <<validate_slab_cache>> unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
+ * - mm/slub.c|4149| <<list_locations>> unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
+ * - mm/slub.c|4450| <<objs_per_slab_show>> return sprintf(buf, "%d\n", oo_objects(s->oo));
+ * - mm/slub.c|5374| <<get_slabinfo>> sinfo->objects_per_slab = oo_objects(s->oo);
+ */
static inline int oo_objects(struct kmem_cache_order_objects x)
{
return x.x & OO_MASK;
@@ -346,6 +472,15 @@ static __always_inline void slab_unlock(struct page *page)
__bit_spin_unlock(PG_locked, &page->flags);
}
+/*
+ * called by:
+ * - mm/slub.c|427| <<__cmpxchg_double_slab>> set_page_slub_counters(page, counters_new);
+ * - mm/slub.c|466| <<cmpxchg_double_slab>> set_page_slub_counters(page, counters_new);
+ *
+ * page->counters和{page->frozen, page->inuse, page->objects}属于一个union
+ * 设置page->counters=counters_new...
+ * 等价于设置page->frozen,page->inuse,page->projects
+ */
static inline void set_page_slub_counters(struct page *page, unsigned long counters_new)
{
struct page tmp;
@@ -362,6 +497,18 @@ static inline void set_page_slub_counters(struct page *page, unsigned long count
}
/* Interrupts must be disabled (for the fallback code to work right) */
+/*
+ * called by:
+ * - mm/slub.c|2036| <<acquire_slab>> if (!__cmpxchg_double_slab(s, page,
+ * - mm/slub.c|2298| <<deactivate_slab>> } while (!__cmpxchg_double_slab(s, page,
+ * - mm/slub.c|2387| <<deactivate_slab>> if (!__cmpxchg_double_slab(s, page,
+ * - mm/slub.c|2449| <<unfreeze_partials>> } while (!__cmpxchg_double_slab(s, page,
+ * - mm/slub.c|2742| <<get_freelist>> } while (!__cmpxchg_double_slab(s, page,
+ *
+ * 我们期待__cmpxchg_double_slab()返回true, 不希望false
+ * 核心思想是判断page->freelist和page->counters是否和old的相等
+ * 如果相等,则把page->freelist和page->counters都更新成新的
+ */
static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new,
@@ -399,6 +546,14 @@ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page
return false;
}
+/*
+ * called by:
+ * - mm/slub.c|3165| <<__slab_free>> } while (!cmpxchg_double_slab(s, page,
+ *
+ * 我们期待cmpxchg_double_slab()返回true, 不希望false
+ * 核心思想是判断page->freelist和page->counters是否和old的相等
+ * 如果相等,则把page->freelist和page->counters都更新成新的
+ */
static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new,
@@ -447,6 +602,12 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
* Node listlock must be held to guarantee that the page does
* not vanish from under us.
*/
+/*
+ * called by:
+ * - mm/slub.c|3756| <<list_slab_objects>> get_map(s, page, map);
+ * - mm/slub.c|4431| <<validate_slab>> get_map(s, page, map);
+ * - mm/slub.c|4656| <<process_slab>> get_map(s, page, map);
+ */
static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
{
void *p;
@@ -474,11 +635,25 @@ static int disable_higher_order_debug;
* be reported by kasan as a bounds error. metadata_access_enable() is used
* to tell kasan that these accesses are OK.
*/
+/*
+ * called by:
+ * - mm/slub.c|622| <<print_section>> metadata_access_enable();
+ * - mm/slub.c|655| <<set_track>> metadata_access_enable();
+ * - mm/slub.c|879| <<check_bytes_and_report>> metadata_access_enable();
+ * - mm/slub.c|987| <<slab_pad_check>> metadata_access_enable();
+ */
static inline void metadata_access_enable(void)
{
kasan_disable_current();
}
+/*
+ * called by:
+ * - mm/slub.c|625| <<print_section>> metadata_access_disable();
+ * - mm/slub.c|657| <<set_track>> metadata_access_disable();
+ * - mm/slub.c|881| <<check_bytes_and_report>> metadata_access_disable();
+ * - mm/slub.c|989| <<slab_pad_check>> metadata_access_disable();
+ */
static inline void metadata_access_disable(void)
{
kasan_enable_current();
@@ -487,6 +662,17 @@ static inline void metadata_access_disable(void)
/*
* Object debugging
*/
+/*
+ * called by:
+ * - mm/slub.c|786| <<print_trailer>> print_section("Bytes b4 ", p - 16, 16);
+ * - mm/slub.c|788| <<print_trailer>> print_section("Object ", p, min_t(unsigned long , s->object_size,
+ * - mm/slub.c|791| <<print_trailer>> print_section("Redzone ", p + s->object_size,
+ * - mm/slub.c|804| <<print_trailer>> print_section("Padding ", p + off, s->size - off);
+ * - mm/slub.c|996| <<slab_pad_check>> print_section("Padding ", end - remainder, remainder);
+ * - mm/slub.c|1179| <<trace>> print_section("Object ", (void *)object,
+ *
+ * 就是打印一些hex的数据,没有修改
+ */
static void print_section(char *text, u8 *addr, unsigned int length)
{
metadata_access_enable();
@@ -495,6 +681,13 @@ static void print_section(char *text, u8 *addr, unsigned int length)
metadata_access_disable();
}
+/*
+ * called by:
+ * - mm/slub.c|644| <<set_track>> struct track *p = get_track(s, object, alloc);
+ * - mm/slub.c|718| <<print_tracking>> print_track("Allocated", get_track(s, object, TRACK_ALLOC));
+ * - mm/slub.c|719| <<print_tracking>> print_track("Freed", get_track(s, object, TRACK_FREE));
+ * - mm/slub.c|4465| <<process_slab>> add_location(t, s, get_track(s, p, alloc));
+ */
static struct track *get_track(struct kmem_cache *s, void *object,
enum track_item alloc)
{
@@ -508,6 +701,13 @@ static struct track *get_track(struct kmem_cache *s, void *object,
return p + alloc;
}
+/*
+ * called by:
+ * - mm/slub.c|680| <<init_tracking>> set_track(s, object, TRACK_FREE, 0UL);
+ * - mm/slub.c|681| <<init_tracking>> set_track(s, object, TRACK_ALLOC, 0UL);
+ * - mm/slub.c|1284| <<alloc_debug_processing>> set_track(s, object, TRACK_ALLOC, addr);
+ * - mm/slub.c|1358| <<free_debug_processing>> set_track(s, object, TRACK_FREE, addr);
+ */
static void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr)
{
@@ -542,6 +742,11 @@ static void set_track(struct kmem_cache *s, void *object,
memset(p, 0, sizeof(struct track));
}
+/*
+ * called by:
+ * - mm/slub.c|1252| <<setup_object_debug>> init_tracking(s, object);
+ * - mm/slub.c|3308| <<early_kmem_cache_node_alloc>> init_tracking(kmem_cache_node, n);
+ */
static void init_tracking(struct kmem_cache *s, void *object)
{
if (!(s->flags & SLAB_STORE_USER))
@@ -551,6 +756,11 @@ static void init_tracking(struct kmem_cache *s, void *object)
set_track(s, object, TRACK_ALLOC, 0UL);
}
+/*
+ * called by:
+ * - mm/slub.c|706| <<print_tracking>> print_track("Allocated", get_track(s, object, TRACK_ALLOC));
+ * - mm/slub.c|707| <<print_tracking>> print_track("Freed", get_track(s, object, TRACK_FREE));
+ */
static void print_track(const char *s, struct track *t)
{
if (!t->addr)
@@ -570,6 +780,11 @@ static void print_track(const char *s, struct track *t)
#endif
}
+/*
+ * called by:
+ * - mm/slub.c|750| <<print_trailer>> print_tracking(s, p);
+ * - mm/slub.c|3465| <<list_slab_objects>> print_tracking(s, p);
+ */
static void print_tracking(struct kmem_cache *s, void *object)
{
if (!(s->flags & SLAB_STORE_USER))
@@ -579,6 +794,13 @@ static void print_tracking(struct kmem_cache *s, void *object)
print_track("Freed", get_track(s, object, TRACK_FREE));
}
+/*
+ * called by:
+ * - mm/slub.c|780| <<print_trailer>> print_page_info(page);
+ * - mm/slub.c|826| <<slab_err>> print_page_info(page);
+ *
+ * 就是用pr_err()打印log, 没有修改
+ */
static void print_page_info(struct page *page)
{
pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n",
@@ -586,6 +808,14 @@ static void print_page_info(struct page *page)
}
+/*
+ * called by:
+ * - mm/slub.c|864| <<object_err>> slab_bug(s, "%s", reason);
+ * - mm/slub.c|877| <<slab_err>> slab_bug(s, "%s", buf);
+ * - mm/slub.c|941| <<check_bytes_and_report>> slab_bug(s, "%s overwritten", what);
+ *
+ * 就是打印log, 没有修改
+ */
static void slab_bug(struct kmem_cache *s, char *fmt, ...)
{
struct va_format vaf;
@@ -602,6 +832,17 @@ static void slab_bug(struct kmem_cache *s, char *fmt, ...)
va_end(args);
}
+/*
+ * called by:
+ * - mm/slub.c|838| <<restore_bytes>> slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
+ * - mm/slub.c|1062| <<on_freelist>> slab_fix(s, "Freelist cleared");
+ * - mm/slub.c|1080| <<on_freelist>> slab_fix(s, "Number of objects adjusted.");
+ * - mm/slub.c|1086| <<on_freelist>> slab_fix(s, "Object count adjusted.");
+ * - mm/slub.c|1211| <<alloc_debug_processing>> slab_fix(s, "Marking all objects used");
+ * - mm/slub.c|1276| <<free_debug_processing>> slab_fix(s, "Object at 0x%p not freed", object);
+ *
+ * slab_fix()就是打印几句错误
+ */
static void slab_fix(struct kmem_cache *s, char *fmt, ...)
{
struct va_format vaf;
@@ -614,6 +855,13 @@ static void slab_fix(struct kmem_cache *s, char *fmt, ...)
va_end(args);
}
+/*
+ * called by:
+ * - mm/slub.c|785| <<object_err>> print_trailer(s, page, object);
+ * - mm/slub.c|842| <<check_bytes_and_report>> print_trailer(s, page, object);
+ *
+ * 就是打印log, 没有修改
+ */
static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
{
unsigned int off; /* Offset of last byte */
@@ -621,11 +869,15 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
print_tracking(s, p);
+ /* 就是用pr_err()打印log, 没有修改 */
print_page_info(page);
pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
p, p - addr, get_freepointer(s, p));
+ /*
+ * print_section()就是打印一些hex的数据,没有修改
+ */
if (p > addr + 16)
print_section("Bytes b4 ", p - 16, 16);
@@ -650,13 +902,41 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
dump_stack();
}
+/*
+ * called by:
+ * - mm/kasan/report.c|120| <<print_address_description>> object_err(cache, page, object,
+ * - mm/slub.c|1103| <<check_object>> object_err(s, page, p, "Freepointer corrupt");
+ * - mm/slub.c|1184| <<on_freelist>> object_err(s, page, object,
+ * - mm/slub.c|1327| <<alloc_debug_processing>> object_err(s, page, object, "Freelist Pointer check fails");
+ * - mm/slub.c|1387| <<free_debug_processing>> object_err(s, page, object, "Object already free");
+ * - mm/slub.c|1404| <<free_debug_processing>> object_err(s, page, object,
+ *
+ * 就是打印log, 没有修改
+ */
void object_err(struct kmem_cache *s, struct page *page,
u8 *object, char *reason)
{
+ /* 就是打印log, 没有修改 */
slab_bug(s, "%s", reason);
+ /* 就是打印log, 没有修改 */
print_trailer(s, page, object);
}
+/*
+ * called by:
+ * - mm/slub.c|1047| <<slab_pad_check>> slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
+ * - mm/slub.c|1135| <<check_slab>> slab_err(s, page, "Not a valid slab page");
+ * - mm/slub.c|1142| <<check_slab>> slab_err(s, page, "objects %u > max %u",
+ * - mm/slub.c|1148| <<check_slab>> slab_err(s, page, "inuse %u > max %u",
+ * - mm/slub.c|1188| <<on_freelist>> slab_err(s, page, "Freepointer corrupt");
+ * - mm/slub.c|1206| <<on_freelist>> slab_err(s, page, "Wrong number of objects. Found %d but "
+ * - mm/slub.c|1212| <<on_freelist>> slab_err(s, page, "Wrong object count. Counter is %d but "
+ * - mm/slub.c|1381| <<free_debug_processing>> slab_err(s, page, "Invalid object pointer 0x%p", object);
+ * - mm/slub.c|1397| <<free_debug_processing>> slab_err(s, page, "Attempt to free object(0x%p) "
+ * - mm/slub.c|3629| <<list_slab_objects>> slab_err(s, page, text, s->name);
+ *
+ * 就是打印log, 没有修改
+ */
static void slab_err(struct kmem_cache *s, struct page *page,
const char *fmt, ...)
{
@@ -666,11 +946,19 @@ static void slab_err(struct kmem_cache *s, struct page *page,
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
+ /* 就是打印log, 没有修改 */
slab_bug(s, "%s", buf);
print_page_info(page);
dump_stack();
}
+/*
+ * called by:
+ * - mm/slub.c|1187| <<setup_object_debug>> init_object(s, object, SLUB_RED_INACTIVE);
+ * - mm/slub.c|1214| <<alloc_debug_processing>> init_object(s, object, SLUB_RED_ACTIVE);
+ * - mm/slub.c|1277| <<free_debug_processing>> init_object(s, object, SLUB_RED_INACTIVE);
+ * - mm/slub.c|3224| <<early_kmem_cache_node_alloc>> init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
+ */
static void init_object(struct kmem_cache *s, void *object, u8 val)
{
u8 *p = object;
@@ -684,13 +972,32 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
memset(p + s->object_size, val, s->inuse - s->object_size);
}
+/*
+ * called by:
+ * - mm/slub.c|844| <<check_bytes_and_report>> restore_bytes(s, what, value, fault, end);
+ * - mm/slub.c|935| <<slab_pad_check>> restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
+ *
+ * 在用slab_fix()打印log后会用memset()恢复数据!!!!!
+ */
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
+ /* slab_fix()就是打印几句错 */
slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
+ /* 这句才是真正restore用的 */
memset(from, data, to - from);
}
+/*
+ * called by:
+ * - mm/slub.c|943| <<check_pad_bytes>> return check_bytes_and_report(s, page, p, "Object padding",
+ * - mm/slub.c|1006| <<check_object>> if (!check_bytes_and_report(s, page, object, "Redzone",
+ * - mm/slub.c|1011| <<check_object>> check_bytes_and_report(s, page, p, "Alignment padding",
+ * - mm/slub.c|1019| <<check_object>> (!check_bytes_and_report(s, page, p, "Poison", p,
+ * - mm/slub.c|1021| <<check_object>> !check_bytes_and_report(s, page, p, "Poison",
+ *
+ * 检查之后会恢复数据---> FIX FIX FIX !!!
+ */
static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *object, char *what,
u8 *start, unsigned int value, unsigned int bytes)
@@ -699,6 +1006,11 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *end;
metadata_access_enable();
+ /*
+ * Find an unmatching character in an area of memory.
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
fault = memchr_inv(start, value, bytes);
metadata_access_disable();
if (!fault)
@@ -708,11 +1020,14 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
while (end > fault && end[-1] == value)
end--;
+ /* 就是打印log, 没有修改 */
slab_bug(s, "%s overwritten", what);
pr_err("INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n",
fault, end - 1, fault[0], value);
+ /* 就是打印log, 没有修改 */
print_trailer(s, page, object);
+ /* 在用slab_fix()打印log后会用memset()恢复数据!!!!! */
restore_bytes(s, what, value, fault, end);
return 0;
}
@@ -755,6 +1070,13 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
* may be used with merged slabcaches.
*/
+/*
+ * called by:
+ * - mm/slub.c|1027| <<check_object>> check_pad_bytes(s, page, p);
+ *
+ * 这里是检查object最后(包括debug info)到最后之间的数据是否是POISON_INUSE
+ * 如果不是,恢复修改这些padding!!! ----> FIX FIX FIX!!!!
+ */
static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
{
unsigned long off = s->inuse; /* The end of info */
@@ -770,11 +1092,20 @@ static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
if (s->size == off)
return 1;
+ /* 检查之后会恢复数据---> FIX FIX FIX !!! */
return check_bytes_and_report(s, page, p, "Object padding",
p + off, POISON_INUSE, s->size - off);
}
/* Check the pad bytes at the end of a slab page */
+/*
+ * called by:
+ * - mm/slub.c|1047| <<check_slab>> slab_pad_check(s, page);
+ * - mm/slub.c|1645| <<__free_slab>> slab_pad_check(s, page);
+ *
+ * 检测page所属的那一组page们的结尾部分是不是都是POISON_INUSE
+ * 不是的话修改过来
+ */
static int slab_pad_check(struct kmem_cache *s, struct page *page)
{
u8 *start;
@@ -783,6 +1114,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
int length;
int remainder;
+ /* 如果没有poison直接返回 */
if (!(s->flags & SLAB_POISON))
return 1;
@@ -808,18 +1140,40 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
return 0;
}
+/*
+ * called by:
+ * - mm/slub.c|1207| <<alloc_debug_processing>> if (!check_object(s, page, object, SLUB_RED_INACTIVE))
+ * - mm/slub.c|1257| <<free_debug_processing>> if (!check_object(s, page, object, SLUB_RED_ACTIVE))
+ * - mm/slub.c|1648| <<__free_slab>> check_object(s, page, p, SLUB_RED_INACTIVE);
+ * - mm/slub.c|4171| <<validate_slab>> if (!check_object(s, page, p, SLUB_RED_INACTIVE))
+ * - mm/slub.c|4177| <<validate_slab>> if (!check_object(s, page, p, SLUB_RED_ACTIVE))
+ *
+ * 我们不希望check_object()返回0
+ */
static int check_object(struct kmem_cache *s, struct page *page,
void *object, u8 val)
{
u8 *p = object;
+ /*
+ * endobject是object之后, 可能还有一些padding数据
+ */
u8 *endobject = object + s->object_size;
if (s->flags & SLAB_RED_ZONE) {
+ /*
+ * 检查之后会恢复数据---> FIX FIX FIX !!!
+ */
if (!check_bytes_and_report(s, page, object, "Redzone",
endobject, val, s->inuse - s->object_size))
return 0;
} else {
if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
+ /*
+ * endobject是object之后, 可能还有一些padding数据
+ * 检查object和fp之间的padding是否是POISON_INUSE(初始化设置的)
+ *
+ * 检查之后会恢复数据---> FIX FIX FIX !!!
+ */
check_bytes_and_report(s, page, p, "Alignment padding",
endobject, POISON_INUSE,
s->inuse - s->object_size);
@@ -827,6 +1181,11 @@ static int check_object(struct kmem_cache *s, struct page *page,
}
if (s->flags & SLAB_POISON) {
+ /*
+ * 如果是alloc的时候, 检查object是否是POISON_FREE和POISON_END (最后一位)
+ *
+ * 检查之后会恢复数据---> FIX FIX FIX !!!
+ */
if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
(!check_bytes_and_report(s, page, p, "Poison", p,
POISON_FREE, s->object_size - 1) ||
@@ -836,9 +1195,16 @@ static int check_object(struct kmem_cache *s, struct page *page,
/*
* check_pad_bytes cleans up on its own.
*/
+ /*
+ * 这里是检查object最后(包括debug info)到最后之间的数据是否是POISON_INUSE
+ * 如果不是,恢复修改这些padding!!! ----> FIX FIX FIX!!!!
+ */
check_pad_bytes(s, page, p);
}
+ /*
+ * 这里是free的情况, 如果fp没单拿出来也没法检查
+ */
if (!s->offset && val == SLUB_RED_ACTIVE)
/*
* Object and freepointer overlap. Cannot check
@@ -847,42 +1213,72 @@ static int check_object(struct kmem_cache *s, struct page *page,
return 1;
/* Check free pointer validity */
+ /*
+ * 查看object的地址是否在page的slab的范围内
+ * 如果在返回1, 否则返回0
+ */
if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+ /* 就是打印log, 没有修改 */
object_err(s, page, p, "Freepointer corrupt");
/*
* No choice but to zap it and thus lose the remainder
* of the free objects in this slab. May cause
* another error because the object count is now wrong.
*/
+ /*
+ * 这里会FIX FIX FIX!!!!!!!!!!!
+ */
set_freepointer(s, p, NULL);
return 0;
}
return 1;
}
+/*
+ * called by:
+ * - mm/slub.c|1199| <<alloc_debug_processing>> if (!check_slab(s, page))
+ * - mm/slub.c|1244| <<free_debug_processing>> if (!check_slab(s, page))
+ * - mm/slub.c|4161| <<validate_slab>> if (!check_slab(s, page) ||
+ *
+ * 1. 检查page是否是个slab page (通过PageSlab)
+ * 2. 检查page中所有object的数目是否超过最大可能的值
+ * 3. 检查哦page中正在使用的数目是否超出了支持的数目
+ * 4. 检测page所属的那一组page们的结尾部分是不是都是POISON_INUSE
+ * 不是的话修改过来 ---> FIX FIX FIX !!!!
+ */
static int check_slab(struct kmem_cache *s, struct page *page)
{
int maxobj;
VM_BUG_ON(!irqs_disabled());
+ /* 检查page是否是个slab page (通过PageSlab) */
if (!PageSlab(page)) {
+ /* 就是打印log, 没有修改 */
slab_err(s, page, "Not a valid slab page");
return 0;
}
+ /* 检查page中所有object的数目是否超过最大可能的值 */
maxobj = order_objects(compound_order(page), s->size, s->reserved);
if (page->objects > maxobj) {
+ /* 就是打印log, 没有修改 */
slab_err(s, page, "objects %u > max %u",
page->objects, maxobj);
return 0;
}
+ /* 检查哦page中正在使用的数目是否超出了支持的数目 */
if (page->inuse > page->objects) {
+ /* 就是打印log, 没有修改 */
slab_err(s, page, "inuse %u > max %u",
page->inuse, page->objects);
return 0;
}
/* Slab_pad_check fixes things up after itself */
+ /*
+ * 检测page所属的那一组page们的结尾部分是不是都是POISON_INUSE
+ * 不是的话修改过来 --> FIX FIX FIX!!!
+ */
slab_pad_check(s, page);
return 1;
}
@@ -891,6 +1287,18 @@ static int check_slab(struct kmem_cache *s, struct page *page)
* Determine if a certain object on a page is on the freelist. Must hold the
* slab lock to guarantee that the chains are in a consistent state.
*/
+/*
+ * called by:
+ * - mm/slub.c|1316| <<free_debug_processing>> if (on_freelist(s, page, object)) {
+ * - mm/slub.c|4228| <<validate_slab>> !on_freelist(s, page, NULL))
+ *
+ * 1. 首先遍历page中所有的object, 如果发现要释放的, 则返回1报错
+ * 2. 遍历的过程中如果发现有freelist有问题, 把list直接截断,
+ * 或者把page->freelist直接设置成NULL ---> FIX FIX FIX !!!
+ * 3. 检查这组page的object的数目对不对, 不对修改过来 ---> FIX FIX FIX!
+ *
+ * 期待返回0, 不期待返回1
+ */
static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
{
int nr = 0;
@@ -900,14 +1308,31 @@ static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
fp = page->freelist;
while (fp && nr <= page->objects) {
+ /*
+ * 如果发现要释放的object已经是free的了, 直接返回1报错
+ */
if (fp == search)
return 1;
+ /*
+ * called by:
+ * - mm/slub.c|850| <<check_object>> if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+ * - mm/slub.c|905| <<on_freelist>> if (!check_valid_pointer(s, page, fp)) {
+ * - mm/slub.c|1037| <<alloc_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ * - mm/slub.c|1078| <<free_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ *
+ * 查看object的地址是否在page的范围内
+ * 如果在返回1, 否则返回0
+ */
if (!check_valid_pointer(s, page, fp)) {
if (object) {
object_err(s, page, object,
"Freechain corrupt");
+ /* 让上一个object的freelist指向NULL */
set_freepointer(s, object, NULL);
} else {
+ /*
+ * page->freelist有问题, 把这个page踢出去
+ */
slab_err(s, page, "Freepointer corrupt");
page->freelist = NULL;
page->inuse = page->objects;
@@ -916,11 +1341,17 @@ static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
}
break;
}
+ /*
+ * object一开始是NULL, 用来记录上一个object
+ */
object = fp;
fp = get_freepointer(s, object);
nr++;
}
+ /*
+ * 下面检查这组page的object的数目对不对, 不对修改过来
+ */
max_objects = order_objects(compound_order(page), s->size, s->reserved);
if (max_objects > MAX_OBJS_PER_PAGE)
max_objects = MAX_OBJS_PER_PAGE;
@@ -1027,18 +1458,52 @@ static void setup_object_debug(struct kmem_cache *s, struct page *page,
init_tracking(s, object);
}
+/*
+ * called by:
+ * - mm/slub.c|2564| <<__slab_alloc>> !alloc_debug_processing(s, page, freelist, addr))
+ */
static noinline int alloc_debug_processing(struct kmem_cache *s,
struct page *page,
void *object, unsigned long addr)
{
+ /*
+ * check_slab()在以下调用:
+ * - mm/slub.c|1199| <<alloc_debug_processing>> if (!check_slab(s, page))
+ * - mm/slub.c|1244| <<free_debug_processing>> if (!check_slab(s, page))
+ * - mm/slub.c|4161| <<validate_slab>> if (!check_slab(s, page) ||
+ *
+ * 1. 检查page是否是个slab page (通过PageSlab)
+ * 2. 检查page中所有object的数目是否超过最大可能的值
+ * 3. 检查哦page中正在使用的数目是否超出了支持的数目
+ * 4. 检测page所属的那一组page们的结尾部分是不是都是POISON_INUSE
+ * 不是的话修改过来 ---> FIX FIX FIX !!!!
+ */
if (!check_slab(s, page))
goto bad;
+ /*
+ * check_valid_pointer()在以下调用:
+ * - mm/slub.c|850| <<check_object>> if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+ * - mm/slub.c|905| <<on_freelist>> if (!check_valid_pointer(s, page, fp)) {
+ * - mm/slub.c|1037| <<alloc_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ * - mm/slub.c|1078| <<free_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ *
+ * 查看object的地址是否在page的范围内
+ */
if (!check_valid_pointer(s, page, object)) {
+ /* 就是打印log, 没有修改 */
object_err(s, page, object, "Freelist Pointer check fails");
goto bad;
}
+ /*
+ * check_object()在以下调用:
+ * - mm/slub.c|1207| <<alloc_debug_processing>> if (!check_object(s, page, object, SLUB_RED_INACTIVE))
+ * - mm/slub.c|1257| <<free_debug_processing>> if (!check_object(s, page, object, SLUB_RED_ACTIVE))
+ * - mm/slub.c|1648| <<__free_slab>> check_object(s, page, p, SLUB_RED_INACTIVE);
+ * - mm/slub.c|4171| <<validate_slab>> if (!check_object(s, page, p, SLUB_RED_INACTIVE))
+ * - mm/slub.c|4177| <<validate_slab>> if (!check_object(s, page, p, SLUB_RED_ACTIVE))
+ */
if (!check_object(s, page, object, SLUB_RED_INACTIVE))
goto bad;
@@ -1056,6 +1521,7 @@ bad:
* to avoid issues in the future. Marking all objects
* as used avoids touching the remaining objects.
*/
+ /* slab_fix()就是打印几句错误 */
slab_fix(s, "Marking all objects used");
page->inuse = page->objects;
page->freelist = NULL;
@@ -1063,6 +1529,17 @@ bad:
return 0;
}
+/*
+ * called by:
+ * - mm/slub.c|2801| <<__slab_free>> !(n = free_debug_processing(s, page, x, addr, &flags)))
+ *
+ * kmem_cache_free() or kfree()
+ * -> slab_free()
+ * -> __slab_free()
+ * -> free_debug_processing()
+ *
+ * 被free的时候object还不在page->freelist上
+ */
static noinline struct kmem_cache_node *free_debug_processing(
struct kmem_cache *s, struct page *page, void *object,
unsigned long addr, unsigned long *flags)
@@ -1072,24 +1549,71 @@ static noinline struct kmem_cache_node *free_debug_processing(
spin_lock_irqsave(&n->list_lock, *flags);
slab_lock(page);
+ /*
+ * 调用check_slab()的地方:
+ * - mm/slub.c|1199| <<alloc_debug_processing>> if (!check_slab(s, page))
+ * - mm/slub.c|1244| <<free_debug_processing>> if (!check_slab(s, page))
+ * - mm/slub.c|4161| <<validate_slab>> if (!check_slab(s, page) ||
+ *
+ * 1. 检查page是否是个slab page (通过PageSlab)
+ * 2. 检查page中所有object的数目是否超过最大可能的值
+ * 3. 检查哦page中正在使用的数目是否超出了支持的数目
+ * 4. 检测page所属的那一组page们的结尾部分是不是都是POISON_INUSE
+ * 不是的话修改过来 ---> FIX FIX FIX !!!!
+ */
if (!check_slab(s, page))
goto fail;
+ /*
+ * 调用check_valid_pointer()的地方:
+ * - mm/slub.c|850| <<check_object>> if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
+ * - mm/slub.c|905| <<on_freelist>> if (!check_valid_pointer(s, page, fp)) {
+ * - mm/slub.c|1037| <<alloc_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ * - mm/slub.c|1078| <<free_debug_processing>> if (!check_valid_pointer(s, page, object)) {
+ *
+ * 查看object的地址是否在page的范围内
+ * 如果在返回1, 否则返回0
+ */
if (!check_valid_pointer(s, page, object)) {
+ /* 打印log */
slab_err(s, page, "Invalid object pointer 0x%p", object);
goto fail;
}
+ /*
+ * 调用on_freelist()的地方:
+ * - mm/slub.c|1316| <<free_debug_processing>> if (on_freelist(s, page, object)) {
+ * - mm/slub.c|4228| <<validate_slab>> !on_freelist(s, page, NULL))
+ *
+ * 1. 首先遍历page中所有的object, 如果发现要释放的, 则返回1报错
+ * 2. 遍历的过程中如果发现有freelist有问题, 把list直接截断,