[PATCH 4.4-cip 3/5] mm/slab: clean up DEBUG_PAGEALLOC processing code


Ben Hutchings <ben.hutchings@...>
 

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

commit 40b44137971c2e5865a78f9f7de274449983ccb5 upstream.

Currently, open code for checking DEBUG_PAGEALLOC cache is spread to
some sites. It makes code unreadable and hard to change.

This patch cleans up this code. The following patch will change the
criteria for DEBUG_PAGEALLOC cache so this clean-up will help it, too.

[akpm@linux-foundation.org: fix build with CONFIG_DEBUG_PAGEALLOC=n]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
---
include/linux/mm.h | 12 ++++---
mm/slab.c | 97 +++++++++++++++++++++++++++---------------------------
2 files changed, 57 insertions(+), 52 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f0ffa01c90d9..b93d147439f9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2148,14 +2148,18 @@ kernel_map_pages(struct page *page, int numpages, int enable)
}
#ifdef CONFIG_HIBERNATION
extern bool kernel_page_present(struct page *page);
-#endif /* CONFIG_HIBERNATION */
-#else
+#endif /* CONFIG_HIBERNATION */
+#else /* CONFIG_DEBUG_PAGEALLOC */
static inline void
kernel_map_pages(struct page *page, int numpages, int enable) {}
#ifdef CONFIG_HIBERNATION
static inline bool kernel_page_present(struct page *page) { return true; }
-#endif /* CONFIG_HIBERNATION */
-#endif
+#endif /* CONFIG_HIBERNATION */
+static inline bool debug_pagealloc_enabled(void)
+{
+ return false;
+}
+#endif /* CONFIG_DEBUG_PAGEALLOC */

#ifdef __HAVE_ARCH_GATE_AREA
extern struct vm_area_struct *get_gate_vma(struct mm_struct *mm);
diff --git a/mm/slab.c b/mm/slab.c
index 62a7e4d3dde3..aa11af56f139 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1670,6 +1670,14 @@ static void kmem_rcu_free(struct rcu_head *head)
}

#if DEBUG
+static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
+{
+ if (debug_pagealloc_enabled() && OFF_SLAB(cachep) &&
+ (cachep->size % PAGE_SIZE) == 0)
+ return true;
+
+ return false;
+}

#ifdef CONFIG_DEBUG_PAGEALLOC
static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
@@ -1703,6 +1711,23 @@ static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
}
*addr++ = 0x87654321;
}
+
+static void slab_kernel_map(struct kmem_cache *cachep, void *objp,
+ int map, unsigned long caller)
+{
+ if (!is_debug_pagealloc_cache(cachep))
+ return;
+
+ if (caller)
+ store_stackinfo(cachep, objp, caller);
+
+ kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
+}
+
+#else
+static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
+ int map, unsigned long caller) {}
+
#endif

static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
@@ -1781,6 +1806,9 @@ static void check_poison_obj(struct kmem_cache *cachep, void *objp)
int size, i;
int lines = 0;

+ if (is_debug_pagealloc_cache(cachep))
+ return;
+
realobj = (char *)objp + obj_offset(cachep);
size = cachep->object_size;

@@ -1846,17 +1874,8 @@ static void slab_destroy_debugcheck(struct kmem_cache *cachep,
void *objp = index_to_obj(cachep, page, i);

if (cachep->flags & SLAB_POISON) {
-#ifdef CONFIG_DEBUG_PAGEALLOC
- if (debug_pagealloc_enabled() &&
- cachep->size % PAGE_SIZE == 0 &&
- OFF_SLAB(cachep))
- kernel_map_pages(virt_to_page(objp),
- cachep->size / PAGE_SIZE, 1);
- else
- check_poison_obj(cachep, objp);
-#else
check_poison_obj(cachep, objp);
-#endif
+ slab_kernel_map(cachep, objp, 1, 0);
}
if (cachep->flags & SLAB_RED_ZONE) {
if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
@@ -2237,16 +2256,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (flags & CFLGS_OFF_SLAB) {
/* really off slab. No need for manual alignment */
freelist_size = calculate_freelist_size(cachep->num, 0);
-
-#ifdef CONFIG_PAGE_POISONING
- /* If we're going to use the generic kernel_map_pages()
- * poisoning, then it's going to smash the contents of
- * the redzone and userword anyhow, so switch them off.
- */
- if (debug_pagealloc_enabled() &&
- size % PAGE_SIZE == 0 && flags & SLAB_POISON)
- flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
-#endif
}

cachep->colour_off = cache_line_size();
@@ -2262,7 +2271,19 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
cachep->size = size;
cachep->reciprocal_buffer_size = reciprocal_value(size);

- if (flags & CFLGS_OFF_SLAB) {
+#if DEBUG
+ /*
+ * If we're going to use the generic kernel_map_pages()
+ * poisoning, then it's going to smash the contents of
+ * the redzone and userword anyhow, so switch them off.
+ */
+ if (IS_ENABLED(CONFIG_PAGE_POISONING) &&
+ (cachep->flags & SLAB_POISON) &&
+ is_debug_pagealloc_cache(cachep))
+ cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
+#endif
+
+ if (OFF_SLAB(cachep)) {
cachep->freelist_cache = kmalloc_slab(freelist_size, 0u);
/*
* This is a possibility for one of the kmalloc_{dma,}_caches.
@@ -2489,9 +2510,6 @@ static void cache_init_objs(struct kmem_cache *cachep,
for (i = 0; i < cachep->num; i++) {
void *objp = index_to_obj(cachep, page, i);
#if DEBUG
- /* need to poison the objs? */
- if (cachep->flags & SLAB_POISON)
- poison_obj(cachep, objp, POISON_FREE);
if (cachep->flags & SLAB_STORE_USER)
*dbg_userword(cachep, objp) = NULL;

@@ -2515,10 +2533,11 @@ static void cache_init_objs(struct kmem_cache *cachep,
slab_error(cachep, "constructor overwrote the"
" start of an object");
}
- if ((cachep->size % PAGE_SIZE) == 0 &&
- OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
- kernel_map_pages(virt_to_page(objp),
- cachep->size / PAGE_SIZE, 0);
+ /* need to poison the objs? */
+ if (cachep->flags & SLAB_POISON) {
+ poison_obj(cachep, objp, POISON_FREE);
+ slab_kernel_map(cachep, objp, 0, 0);
+ }
#else
if (cachep->ctor)
cachep->ctor(objp);
@@ -2737,18 +2756,8 @@ static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,

set_obj_status(page, objnr, OBJECT_FREE);
if (cachep->flags & SLAB_POISON) {
-#ifdef CONFIG_DEBUG_PAGEALLOC
- if (debug_pagealloc_enabled() &&
- (cachep->size % PAGE_SIZE) == 0 && OFF_SLAB(cachep)) {
- store_stackinfo(cachep, objp, caller);
- kernel_map_pages(virt_to_page(objp),
- cachep->size / PAGE_SIZE, 0);
- } else {
- poison_obj(cachep, objp, POISON_FREE);
- }
-#else
poison_obj(cachep, objp, POISON_FREE);
-#endif
+ slab_kernel_map(cachep, objp, 0, caller);
}
return objp;
}
@@ -2875,16 +2884,8 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
if (!objp)
return objp;
if (cachep->flags & SLAB_POISON) {
-#ifdef CONFIG_DEBUG_PAGEALLOC
- if (debug_pagealloc_enabled() &&
- (cachep->size % PAGE_SIZE) == 0 && OFF_SLAB(cachep))
- kernel_map_pages(virt_to_page(objp),
- cachep->size / PAGE_SIZE, 1);
- else
- check_poison_obj(cachep, objp);
-#else
check_poison_obj(cachep, objp);
-#endif
+ slab_kernel_map(cachep, objp, 1, 0);
poison_obj(cachep, objp, POISON_INUSE);
}
if (cachep->flags & SLAB_STORE_USER)
--
2.10.2



--
Ben Hutchings
Software Developer, Codethink Ltd.

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