Messages in this thread | | | Date | Wed, 2 Oct 2013 17:25:28 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH] slub: Proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled |
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On Wed, Oct 02, 2013 at 04:57:12PM +0100, Christoph Lameter wrote: > On Wed, 2 Oct 2013, Bird, Tim wrote: > > > The problem child is actually the unconditional call to kmemleak_alloc() > > in kmalloc_large_node() (in slub.c). The problem comes because that call > > is unconditional on CONFIG_SLUB_DEBUG but the kmemleak > > calls in the hook routines are conditional on CONFIG_SLUB_DEBUG. > > So if you have CONFIG_SLUB_DEBUG=n but CONFIG_DEBUG_KMEMLEAK=y, > > you get the false reports. > > Right. You need to put the #ifdef CONFIG_SLUB_DEBUG around the hooks that > need it in the function itself instead of disabling the whole function if > CONFIG_SLUB_DEUBG is not set.
If we are to do this, we also need a DEBUG_KMEMLEAK dependency, something like:
depends on (SLUB && SLUB_DEBUG) || !SLUB
or
select SLUB_DEBUG if SLUB
Otherwise you get a lot of false positives.
But with any of the above, #ifdef'ing out kmemleak_* calls wouldn't make much difference since they would already be no-ops in kmemleak.h with !SLUB_DEBUG.
> > Personally, I like the idea of keeping bookeeping/tracing/debug stuff in hook > > routines. I also like de-coupling CONFIG_SLUB_DEBUG and CONFIG_DEBUG_KMEMLEAK, > > but maybe others have a different opinon. Unless someone speaks up, we'll > > move the the currently in-function kmemleak calls into hooks, and all of the > > kmemleak stuff out from under CONFIG_SLUB_DEBUG. > > We'll have to see if the ifdefs get a little messy. > > Decouple of you want. CONFIG_SLUB_DEBUG may duplicate what you already do.
I would prefer the decoupling but I'm fine either way (as long as the dependencies are in place).
-- Catalin
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