Messages in this thread | | | From | "chenjun (AM)" <> | Subject | Re: [PATCH] trace: Fix a kmemleak noise | Date | Thu, 25 Nov 2021 01:48:20 +0000 |
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在 2021/11/24 23:16, Steven Rostedt 写道: Hi
> On Wed, 24 Nov 2021 14:08:01 +0000 > Chen Jun <chenjun102@huawei.com> wrote: > >> The reason is elts->pages[i] is alloced by get_zeroed_page. >> and kmemleak will not scan the area alloced by get_zeroed_page. >> The address stored in elts->pages will be regarded as leaked. > > Why doesn't kmemleak scan get_zeroed_page? And if that's the case, how does > all the other locations in the kernel that call get_zeroed_page handle this? > I think in most cases, the page do not contain pointers. But I am not sure. Maybe we should better ask Catalin.
In block/blk-mq.c blk_mq_alloc_rqs .. page = alloc_pages_node(node,.. .. p = page_address(page); /*$ * Allow kmemleak to scan these pages as they contain pointers * to additional allocations like via ops->init_request(). */$ kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
In lib/scatterlist.c static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) { if (nents == SG_MAX_SINGLE_ALLOC) { /* * Kmemleak doesn't track page allocations as they are not * commonly used (in a raw form) for kernel data structures. * As we chain together a list of pages and then a normal * kmalloc (tracked by kmemleak), in order to for that last * allocation not to become decoupled (and thus a * false-positive) we need to inform kmemleak of all the * intermediate allocations. */ void *ptr = (void *) __get_free_page(gfp_mask); kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); return ptr; ..
> -- Steve >
-- Regards Chen Jun
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