Re: [PATCH] mm: percpu: use kmemleak_ignore_phys() instead of kmemleak_free()

[patrick wang]

On Wed, Jul 6, 2022 at 5:20 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue,  5 Jul 2022 19:31:58 +0800 Patrick Wang <patrick.wang.shcn@xxxxxxxxx> wrote:
>
> > Kmemleak recently added a rbtree to store the objects
> > allocted with physical address. Those objects can't be
> > freed with kmemleak_free(). Use kmemleak_ignore_phys()
> > instead of kmemleak_free() for those objects.
>
> Thanks.  What are the user-visible runtime effects of this?

According to the comments, percpu allocations are tracked
by kmemleak separately. Kmemleak_free() was used to avoid
the unnecessary tracking. If kmemleak_free() fails, those
objects would be scanned by kmemleak, which is unnecessary
but shouldn't lead to other effects.

I didn't observe any anomaly without this commit on riscv
and arm64.

>
> And are we able to identify a commit for the Fixes: line?

0c24e061196c (mm: kmemleak: add rbtree and store physical
address for objects allocated with PA)
Current in mm-stable.

Thanks,
Patrick