From: Mike Rapoport <rppt@linux.ibm.com>
To: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Anshuman Khandual <anshuman.khandual@arm.com>,
Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH] mm, page_alloc: check pfn is valid before moving to freelist
Date: Tue, 19 Apr 2022 09:45:59 +0300 [thread overview]
Message-ID: <Yl5ap4veIr5ugce1@linux.ibm.com> (raw)
In-Reply-To: <85dfcf28-7e43-7bfe-d63a-97dde28cf207@quicinc.com>
On Mon, Apr 18, 2022 at 03:32:21PM -0700, Sudarshan Rajagopalan wrote:
> On 4/18/2022 12:24 AM, Mike Rapoport wrote:
> > On Fri, Apr 15, 2022 at 02:30:52AM +0530, Sudarshan Rajagopalan wrote:
> > > On 4/14/2022 2:18 AM, Mike Rapoport wrote:
> > >
> > > We have a feature where we carve out some portion of memory in RAM partition
> > > table, hence we see such base addresses here.
> > >
> > Cannot the firmware align that portion at some sensible boundary?
> > Or at least report the carved out range as "reserved" (and maybe NOMAP)
> > rather than as hole?
>
> We can have the firmware or ABL align the address to next pageblock size
> boundary. This would simple mean loosing few MBs of memory with alignment.
> Same with making them as "reserved" with "nomap".
Reserved and nomap do not have to be aligned and there will be a valid
struct page for such regions.
Still, the kernel should be able to cope with firmware oddities so a fix
for 5.15 is still needed.
> > That said, your patch will not fix anything in the current kernel because
> > the issue should not happen there, right?
>
> Yes, the issue seems to be fixed in latest kernel version with the patches
> to drop arm64 pfn_valid. But the core issue is present on previous kernel
> versions with the scenario explained. Any procedure to have this fixed on
> 5.15 kernel?
>
> > I'd suggest backporting a9c38c5d267c ("dma-mapping: remove bogus test for
> > pfn_valid from dma_map_resource") and 3de360c3fdb3 ("arm64/mm: drop
> > HAVE_ARCH_PFN_VALID") to 5.15.
>
> The issue is not seen with these patches backported. Not sure of the
> procedure to send patches for 5.15 kernel, but can we have them backported
> to 5.15?
Please look at Documentation/process/stable-kernel-rules.rst for
explanation how to send patches to stable kernels.
--
Sincerely yours,
Mike.
prev parent reply other threads:[~2022-04-19 6:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 20:16 [PATCH] mm, page_alloc: check pfn is valid before moving to freelist Sudarshan Rajagopalan
2022-04-12 20:16 ` Sudarshan Rajagopalan
2022-04-12 20:59 ` Andrew Morton
2022-04-12 21:05 ` David Rientjes
2022-04-13 20:55 ` Mike Rapoport
2022-04-14 14:02 ` David Hildenbrand
2022-04-13 20:48 ` Mike Rapoport
2022-04-14 21:00 ` Sudarshan Rajagopalan
2022-04-18 7:24 ` Mike Rapoport
2022-04-18 22:32 ` Sudarshan Rajagopalan
2022-04-19 6:45 ` Mike Rapoport [this message]
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