The patch titled
Subject: mm: kmemleak: make the tool tolerant to struct scan_area allocation failures
has been added to the -mm tree. Its filename is
mm-kmemleak-make-the-tool-tolerant-to-struct-scan_area-allocation-failures.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kmemleak-make-the-tool-tolerant-to-struct-scan_area-allocation-failures.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kmemleak-make-the-tool-tolerant-to-struct-scan_area-allocation-failures.patch
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------------------------------------------------------
From: Catalin Marinas <catalin.marinas@xxxxxxx>
Subject: 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@xxxxxxx
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@xxxxxxx
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmemleak.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
--- a/mm/kmemleak.c~mm-kmemleak-make-the-tool-tolerant-to-struct-scan_area-allocation-failures
+++ a/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
}
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
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_
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;
_
Patches currently in -mm which might be from catalin.marinas@xxxxxxx are
mm-kmemleak-disable-early-logging-in-case-of-error.patch
mm-kmemleak-make-the-tool-tolerant-to-struct-scan_area-allocation-failures.patch
mm-kmemleak-simple-memory-allocation-pool-for-kmemleak-objects.patch
mm-kmemleak-use-the-memory-pool-for-early-allocations.patch
