Hi Greg, 7f88f88f83ed609650a01b18572e605ea50cd163 mm: kmemleak: avoid false negatives on vmalloc'ed objects
This patch looks applicable to stable-3.4, it fixed a regression that kmemleak was rarely reporting vmalloc() leaks. It was tested fine by me. This patch needs some adjustments, before apply this patch, please cherry-pick a preparation patch: a3860c1c5dd1137db23d7786d284939c5761d517 introduce SIZE_MAX ---------------------------------- From: Catalin Marinas <[email protected]> commit 7f88f88f83ed609650a01b18572e605ea50cd163 upstream. Commit 248ac0e1943a ("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 <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> [hq: Backported to 3.4: Adjust context] Signed-off-by: Qiang Huang <[email protected]> --- mm/kmemleak.c | 4 +++- mm/vmalloc.c | 14 ++++++++++---- 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 45eb621..ad6ee88 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -750,7 +750,9 @@ 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); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 1196c77..ad9d900 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -349,6 +349,12 @@ 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); /* @@ -1669,11 +1675,11 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, insert_vmalloc_vmlist(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; -- 1.8.3 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
