linux-kernel - RE: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY

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Date: Fri, 2 Feb 2024 22:46:32 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: Borislav Petkov <bp@...en8.de>
CC: Tong Tiangen <tongtiangen@...wei.com>, Thomas Gleixner
	<tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	"wangkefeng.wang@...wei.com" <wangkefeng.wang@...wei.com>, Dave Hansen
	<dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, "H. Peter
 Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra
	<peterz@...radead.org>, Andrew Morton <akpm@...ux-foundation.org>, "Naoya
 Horiguchi" <naoya.horiguchi@....com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-edac@...r.kernel.org"
	<linux-edac@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>,
	Guohanjun <guohanjun@...wei.com>
Subject: RE: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to
 MCE_IN_KERNEL_COPY_MC

> Now, since you're explaining things today :) pls explain to me what this
> patchset is all about? You having reviewed patch 3 and all?
>
> Why is this pattern:
>
>       if (copy_mc_user_highpage(dst, src, addr, vma)) {
>               memory_failure_queue(page_to_pfn(src), 0);
>
> not good anymore?
>
> Or is the goal here to poison straight from the #MC handler and not
> waste time and potentially get another #MC while memory_failure_queue()
> on the source address is done?
>
> Or something completely different?

See the comment above memory_failure_queue()

* The function is primarily of use for corruptions that
 * happen outside the current execution context (e.g. when
 * detected by a background scrubber)

In the copy_mc_user_highpage() case the fault happens in
the current execution context. So scheduling someone else
to handle it at some future point is risky. Just deal with it
right away.

-Tony