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mm/slab: clean up DEBUG_PAGEALLOC processing code
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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>
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Joonsoo Kim authored and Linus Torvalds committed Mar 15, 2016
1 parent 4032327 commit 40b4413
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Showing 2 changed files with 57 additions and 52 deletions.
12 changes: 8 additions & 4 deletions include/linux/mm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2195,14 +2195,18 @@ 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);
Expand Down
97 changes: 49 additions & 48 deletions mm/slab.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1661,6 +1661,14 @@ 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,
Expand Down Expand Up @@ -1694,6 +1702,23 @@ 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)
Expand Down Expand Up @@ -1772,6 +1797,9 @@ 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;

Expand Down Expand Up @@ -1837,17 +1865,8 @@ 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)
Expand Down Expand Up @@ -2226,16 +2245,6 @@ __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();
Expand All @@ -2251,7 +2260,19 @@ __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.
Expand Down Expand Up @@ -2475,9 +2496,6 @@ 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;

Expand All @@ -2501,10 +2519,11 @@ 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);
Expand Down Expand Up @@ -2716,18 +2735,8 @@ 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;
}
Expand Down Expand Up @@ -2862,16 +2871,8 @@ 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)
Expand Down

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