Re: vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	 Linus Torvalds <torvalds@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 Daniel Borkmann <daniel@iogearbox.net>,
	bpf <bpf@vger.kernel.org>,  Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org
Subject: Re: vm_area at addr ffffffffc0800000 is not marked as VM_IOREMAP
Date: Fri, 8 Mar 2024 14:44:02 -0800	[thread overview]
Message-ID: <CAADnVQJeOc9Muki+-PUYc20-=1vRgkprbNL0zTc=Cz-T_iYkNQ@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQJKPa+JUUKpW7gZehbFBYj3GPrbpd0NCj4xwkU2puObEw@mail.gmail.com>

On Fri, Mar 8, 2024 at 9:53 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Fri, Mar 8, 2024 at 9:24 AM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > On Fri, Mar 08, 2024 at 09:20:24AM -0800, Alexei Starovoitov wrote:
> > > ok. Like the attached patch?
> >
> > Looks sensibe, but I think the powerpc callers of ioremap_page_range
> > will need the same treatment.
>
> Good point. Only one of the callers in arch/powerpc needs adjusting.
> Found few other similar arch users.
> See attached patch.
>
> ioremap_page() in arch/arm/mm/ioremap.c is an interesting case.
> It is EXPORT_SYMBOL, but there are no in-tree users.
> I think we shouldn't apply checks to it,
> since some out-of-tree module may fail.
> I have no arm boards to test, I suggest we play safe than sorry.

I double checked on my newly setup arm64 VM that the fix works.
I believe the regression needs to be fixed today, but
looks like Chritoph is out for today.
So I can either revert the offending commit or
apply the proposed fix to bpf-next.
I'm going to do the latter soon if no one objects.