Re: kmemleak: Cannot insert 0xffffff806e24f000 into the object search tree (overlaps existing) [RPi CM4]

From: Marco Elver <elver@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Will Deacon" <will@kernel.org>,
	"Yee Lee (李建誼)" <Yee.Lee@mediatek.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"Max Schulze" <max.schulze@online.de>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"naush@raspberrypi.com" <naush@raspberrypi.com>,
	"glider@google.com" <glider@google.com>,
	"dvyukov@google.com" <dvyukov@google.com>,
	"kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>
Subject: Re: kmemleak: Cannot insert 0xffffff806e24f000 into the object search tree (overlaps existing) [RPi CM4]
Date: Tue, 16 Aug 2022 17:46:43 +0200	[thread overview]
Message-ID: <CANpmjNMwUKwmOh86p3HnXiU7zLiXvrc8FF5bFHtVAHn=GdaX0g@mail.gmail.com> (raw)
In-Reply-To: <Yvu4bBmykYr+0CXk@arm.com>

On Tue, 16 Aug 2022 at 17:32, Catalin Marinas <catalin.marinas@arm.com> wrote:
[...]
> > Right, looks like the kfence fix didn't need to be in 5.19. In any
> > case, this patch I just sent:
> >
> > https://lore.kernel.org/all/20220816142529.1919543-1-elver@google.com/
> >
> > fixes the issue for 5.19 as well, because memblock has always used
> > kmemleak's kmemleak_*_phys() API and technically we should free it
> > through phys as well.
> >
> > As far as I can tell, that's also the right thing to do in 6.0-rc1
> > with 0c24e061196c2, because we have the slab post-alloc hooks that
> > want to register kfence objects via kmemleak. Unless of course somehow
> > both "ignore" and "free" works, but "ignore" just sounds wrong in this
> > case. Any thoughts?
>
> Since commit 0c24e061196c2, kmemleak has different namespaces for the
> virtual and physical addresses and there is no risk of overlap. So the
> comment in your proposed fix can be confusing in 6.0-rc1 (but fine in
> 5.19).

Makes sense.

> In general, if an object is allocated and never freed,
> kmemleak_ignore*() is more appropriate, so I'm more inclined to only
> send your kmemleak_free_part_phys() fix to 5.19.x rather than mainline.

So it sounds like we should just ask stable to revert 07313a2b29ed
then, if the patch switching to kmemleak_free_part_phys() should not
go to 6.0. Is that the most reasonable option? If so, I'll go ahead
and send stable the email to do so.

Thanks,
-- Marco

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