From: Chris Bainbridge <chris.bainbridge@canonical.com>
To: Pratyush Yadav <pratyush@kernel.org>
Cc: "Mike Rapoport" <rppt@kernel.org>,
"Pasha Tatashin" <pasha.tatashin@soleen.com>,
"Jason Miu" <jasonmiu@google.com>,
"Alexander Graf" <graf@amazon.com>,
"Ran Xiaokai" <ran.xiaokai@zte.com.cn>,
regressions@lists.linux.dev, linux-kernel@vger.kernel.org,
kexec@lists.infradead.org, linux-mm@kvack.org,
"Michał Cłapiński" <mclapinski@google.com>
Subject: Re: [BUG] KHO handover hangs when memmap reserves PMEM
Date: Sun, 4 Oct 2026 16:09:00 +0100 [thread overview]
Message-ID: <asJc1GIBbCJ26akS@px13> (raw)
In-Reply-To: <2vxzcxtplh4i.fsf@kernel.org>
On Sun, Oct 04, 2026 at 03:39:25PM +0200, Pratyush Yadav wrote:
>
> Just to confirm, the first kernel boots without memmap= right?
Yes.
> I think the main problem is that the radix tree pages can be anywhere in
> memory. So on the first kernel, they can land in an area that the second
> kernel's memmap= reserves. So kho_memory_init() might end up using
> memory that memmap= reserved. I'm not sure why exactly the next kernel
> doesn't produce any output, but IIRC memmap= memory is not mapped to the
> direct map, so accessing those pages likely causes a page fault.
That's correct, kho_memory_init() page faults. It happens before the
serial console is available, so there is no output.
next prev parent reply other threads:[~2026-10-04 15:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-03 17:02 [BUG] KHO handover hangs when memmap reserves PMEM Chris Bainbridge
2026-10-04 13:39 ` Pratyush Yadav
2026-10-04 15:09 ` Chris Bainbridge [this message]
2026-10-04 17:53 ` Pratyush Yadav
2026-10-06 10:55 ` Mike Rapoport
2026-10-06 18:02 ` Chris Bainbridge
2026-10-07 6:11 ` Mike Rapoport
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