linux-kernel - Re: [PATCH v2 0/2] x86/mm: support memory-failure on 32-bits with SPARSEMEM

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Message-ID: <20251105090536.11676-1-xieyuanbin1@huawei.com>
Date: Wed, 5 Nov 2025 17:05:36 +0800
From: Xie Yuanbin <xieyuanbin1@...wei.com>
To: <david@...nel.org>, <dave.hansen@...el.com>
CC: <Liam.Howlett@...cle.com>, <akpm@...ux-foundation.org>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <hpa@...or.com>, <liaohua4@...wei.com>,
	<lilinjie8@...wei.com>, <linmiaohe@...wei.com>, <linux-edac@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	<lorenzo.stoakes@...cle.com>, <luto@...nel.org>, <mhocko@...e.com>,
	<mingo@...hat.com>, <nao.horiguchi@...il.com>, <peterz@...radead.org>,
	<rppt@...nel.org>, <surenb@...gle.com>, <tglx@...utronix.de>,
	<tony.luck@...el.com>, <vbabka@...e.cz>, <will@...nel.org>, <x86@...nel.org>,
	<xieyuanbin1@...wei.com>
Subject: Re: [PATCH v2 0/2] x86/mm: support memory-failure on 32-bits with SPARSEMEM

On Wed, 5 Nov 2025 09:12:04 +0100, Dave Hansen wrote:
> Let me clarify what we need to know:
>
> Will you (or your employer) be running such updated 32bit kernels on
> hardware that supports MCEs.
>
> In other words: is this change driver by *real demand*

Thanks! Asking like this, I completely understand now.

We won't directly upgrade the kernel to 6.18.x (or later versions) to use
this feature, but if Linux community approves these patches, we will
backport it to 5.10.x and use it. I know that the page-flags in 5.10.x
have been exhausted, but we can work around them by adjusting
SECTION_SIZE_BITS/MAX_PHYSMEM_BITS to free up a page flag.
Another patch I submitted for arm32:
Link: https://lore.kernel.org/20250922021453.3939-1-xieyuanbin1@huawei.com
, follows the same logic.

Currently, there is a clear demand for ARM32, while the demand for x86 is
still under discussion.

> or just by "oh
> look, we can enable that now, I can come up with a theoretical use case
> but I don't know if anybody would actually care"?

It can also be said that way. In fact, when developing the demand
"support MEMORY_FAILURE for 32-bit OS" in version 5.10.x, I found that the
latest version already supported this feature, so I submitted these
patches, and hope others can benefit from it as well.

> Cheers
>
> David

Thanks!

Xie Yuanbin