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mm: kmemleak: avoid false negatives on vmalloc'ed objects

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Commit 248ac0e194 ("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@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Catalin Marinas 2013-11-12 15:07:45 -08:00 committed by Linus Torvalds
parent 81556b0252
commit 7f88f88f83
2 changed files with 13 additions and 5 deletions
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4
mm/kmemleak.c
View File

@ -753,7 +753,9 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
}
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);

14
mm/vmalloc.c
View File

@ -359,6 +359,12 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
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 size, unsigned long align,
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;