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authorCatalin Marinas <catalin.marinas@arm.com>2019-09-23 15:33:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-24 15:54:07 -0700
commitdba82d9431770e68c45b03f0ffa2daa8abfb9429 (patch)
tree5ee35d76667f8ac32e55de9cc49abfb0b142ac58 /mm/kmemleak.c
parentb751c52bb587ae66f773b15204ef7a147467f4c7 (diff)
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mm: kmemleak: make the tool tolerant to struct scan_area allocation failures
Patch series "mm: kmemleak: Use a memory pool for kmemleak object allocations", v3. Following the discussions on v2 of this patch(set) [1], this series takes slightly different approach: - it implements its own simple memory pool that does not rely on the slab allocator - drops the early log buffer logic entirely since it can now allocate metadata from the memory pool directly before kmemleak is fully initialised - CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE option is renamed to CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE - moves the kmemleak_init() call earlier (mm_init()) - to avoid a separate memory pool for struct scan_area, it makes the tool robust when such allocations fail as scan areas are rather an optimisation [1] http://lkml.kernel.org/r/20190727132334.9184-1-catalin.marinas@arm.com This patch (of 3): Object scan areas are an optimisation aimed to decrease the false positives and slightly improve the scanning time of large objects known to only have a few specific pointers. If a struct scan_area fails to allocate, kmemleak can still function normally by scanning the full object. Introduce an OBJECT_FULL_SCAN flag and mark objects as such when scan_area allocation fails. Link: http://lkml.kernel.org/r/20190812160642.52134-2-catalin.marinas@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kmemleak.c')
-rw-r--r--mm/kmemleak.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index f6e602918dac..5ba7fad00fda 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -168,6 +168,8 @@ struct kmemleak_object {
#define OBJECT_REPORTED (1 << 1)
/* flag set to not scan the object */
#define OBJECT_NO_SCAN (1 << 2)
+/* flag set to fully scan the object when scan_area allocation failed */
+#define OBJECT_FULL_SCAN (1 << 3)
#define HEX_PREFIX " "
/* number of bytes to print per line; must be 16 or 32 */
@@ -773,12 +775,14 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
}
area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
- if (!area) {
- pr_warn("Cannot allocate a scan area\n");
- goto out;
- }
spin_lock_irqsave(&object->lock, flags);
+ if (!area) {
+ pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
+ /* mark the object for full scan to avoid false positives */
+ object->flags |= OBJECT_FULL_SCAN;
+ goto out_unlock;
+ }
if (size == SIZE_MAX) {
size = object->pointer + object->size - ptr;
} else if (ptr + size > object->pointer + object->size) {
@@ -795,7 +799,6 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
hlist_add_head(&area->node, &object->area_list);
out_unlock:
spin_unlock_irqrestore(&object->lock, flags);
-out:
put_object(object);
}
@@ -1408,7 +1411,8 @@ static void scan_object(struct kmemleak_object *object)
if (!(object->flags & OBJECT_ALLOCATED))
/* already freed object */
goto out;
- if (hlist_empty(&object->area_list)) {
+ if (hlist_empty(&object->area_list) ||
+ object->flags & OBJECT_FULL_SCAN) {
void *start = (void *)object->pointer;
void *end = (void *)(object->pointer + object->size);
void *next;