Messages in this thread | | | From | "Bird, Tim" <> | Date | Wed, 2 Oct 2013 17:33:47 +0200 | Subject | RE: [PATCH] slub: Proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled |
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On Wednesday, October 02, 2013 7:41 AM, Christoph Lameter [cl@linux.com] wrote: > >On Fri, 27 Sep 2013, Frank Rowand wrote: > >> Move the kmemleak code for small block allocation out from >> under CONFIG_SLUB_DEBUG. > >Well in that case it may be better to move the hooks as a whole out of >the CONFIG_SLUB_DEBUG section. Do the #ifdeffering for each call from the >hooks instead. > >The point of the hook functions is to separate the hooks out of the >functions so taht they do not accumulate in the main code. > >The patch moves one hook back into the main code. Please keep the checks >in the hooks.
Thanks for the feedback. Roman's first patch, which we discussed internally before sending this one, did exactly that. I guess Roman gets to say "I told you so." :-) My bad for telling him to change it.
We'll refactor along the lines that you describe, and send another one.
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.
Now, there are kmemleak calls in kmalloc_large_node() and kfree() that don't follow the "hook" pattern. Should these be moved to 'hook' routines, to keep all the checks in the hooks?
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. -- Tim
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