Subject: + mm-kmemleak-avoid-false-negatives-on-vmalloced-objects.patch added to -mm tree
To: catalin.marinas@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 03 Oct 2013 14:33:57 -0700
The patch titled
Subject: mm: kmemleak: avoid false negatives on vmalloc'ed objects
has been added to the -mm tree. Its filename is
mm-kmemleak-avoid-false-negatives-on-vmalloced-objects.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kmemleak-avoid-false-negatives-on-vmalloced-objects.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kmemleak-avoid-false-negatives-on-vmalloced-objects.patch
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------------------------------------------------------
From: Catalin Marinas <catalin.marinas@xxxxxxx>
Subject: mm: kmemleak: avoid false negatives on vmalloc'ed objects
Commit 248ac0e1 ("mm/vmalloc: remove guard page from between vmap blocks")
had the side effect of making vmap_area.va_end member point to the next
vmap_area.va_start. This was creating an artificial reference to
vmalloc'ed objects and kmemleak was rarely reporting vmalloc() leaks.
This patch marks the vmap_area containing pointers explicitly and reduces
the min ref_count to 2 as vm_struct still contains a reference to the
vmalloc'ed object. The kmemleak add_scan_area() function has been
improved to allow a SIZE_MAX argument covering the rest of the object (for
simpler calling sites).
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmemleak.c | 4 +++-
mm/vmalloc.c | 14 ++++++++++----
2 files changed, 13 insertions(+), 5 deletions(-)
diff -puN mm/kmemleak.c~mm-kmemleak-avoid-false-negatives-on-vmalloced-objects mm/kmemleak.c
--- a/mm/kmemleak.c~mm-kmemleak-avoid-false-negatives-on-vmalloced-objects
+++ a/mm/kmemleak.c
@@ -753,7 +753,9 @@ static void add_scan_area(unsigned long
}
spin_lock_irqsave(&object->lock, flags);
- if (ptr + size > object->pointer + object->size) {
+ if (size == SIZE_MAX) {
+ size = object->pointer + object->size - ptr;
+ } else if (ptr + size > object->pointer + object->size) {
kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
dump_object_info(object);
kmem_cache_free(scan_area_cache, area);
diff -puN mm/vmalloc.c~mm-kmemleak-avoid-false-negatives-on-vmalloced-objects mm/vmalloc.c
--- a/mm/vmalloc.c~mm-kmemleak-avoid-false-negatives-on-vmalloced-objects
+++ a/mm/vmalloc.c
@@ -359,6 +359,12 @@ static struct vmap_area *alloc_vmap_area
if (unlikely(!va))
return ERR_PTR(-ENOMEM);
+ /*
+ * Only scan the relevant parts containing pointers to other objects
+ * to avoid false negatives.
+ */
+ kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask & GFP_RECLAIM_MASK);
+
retry:
spin_lock(&vmap_area_lock);
/*
@@ -1645,11 +1651,11 @@ void *__vmalloc_node_range(unsigned long
clear_vm_uninitialized_flag(area);
/*
- * A ref_count = 3 is needed because the vm_struct and vmap_area
- * structures allocated in the __get_vm_area_node() function contain
- * references to the virtual address of the vmalloc'ed block.
+ * A ref_count = 2 is needed because vm_struct allocated in
+ * __get_vm_area_node() contains a reference to the virtual address of
+ * the vmalloc'ed block.
*/
- kmemleak_alloc(addr, real_size, 3, gfp_mask);
+ kmemleak_alloc(addr, real_size, 2, gfp_mask);
return addr;
_
Patches currently in -mm which might be from catalin.marinas@xxxxxxx are
mm-kmemleak-avoid-false-negatives-on-vmalloced-objects.patch
linux-next.patch
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