Re: [RFC PATCH v2] iommu/amd: gray the 'irq_remap_table' object for kmemleak

Joerg Roedel
2015-11-25T15:08:12Z

On Fri, Nov 20, 2015 at 12:33:50PM +0100, Michael Wang wrote:
> The kmemleak testing on 3.18.24 show:
>
> unreferenced object 0xffff880233ff9010 (size 16):
> comm "swapper/0", pid 1, jiffies 4294937440 (age 2010.490s)
> hex dump (first 16 bytes):
> 0a 0a 00 00 20 00 00 00 00 44 fb 33 02 88 ff ff .... ....D.3....
> backtrace:
> [<ffffffff8118192d>] create_object+0x10d/0x2d0
> [<ffffffff815c2d4b>] kmemleak_alloc+0x5b/0xc0
> [<ffffffff8116dd19>] kmem_cache_alloc_trace+0xb9/0x160
> [<ffffffff814ffe51>] get_irq_table+0x151/0x380
>
> This is caused by the 'irq_lookup_table' was allocated with
> __get_free_pages() which won't create kmemleak object, thus it's
> pointers won't be count as referencing 'irq_remap_table' in
> kmemleak scan.

Isn't it better to allocate the kmemleak object manually instead of
ignoring all irq-table pointers? With this patch we might not notice any
real leak of irq-tables.

Joerg