linux-kernel - RE: [PATCH v2 4/5] mm/hwpoison: Fix incorrect "not recovered" report for recovered clean pages

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Message-ID: <SJ1PR11MB608384612B78AF0D65ECC545FCC52@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Wed, 19 Feb 2025 17:15:37 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: Shuai Xue <xueshuai@...ux.alibaba.com>, Miaohe Lin <linmiaohe@...wei.com>
CC: "tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com"
	<mingo@...hat.com>, "dave.hansen@...ux.intel.com"
	<dave.hansen@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>,
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	<nao.horiguchi@...il.com>
Subject: RE: [PATCH v2 4/5] mm/hwpoison: Fix incorrect "not recovered" report
 for recovered clean pages

> > The caller kill_me_maybe will do set_mce_nospec + sync_core again.
> >
> > static void kill_me_maybe(struct callback_head *cb)
> > {
> >     struct task_struct *p = container_of(cb, struct task_struct, mce_kill_me);
> >     int flags = MF_ACTION_REQUIRED;
> >     ...
> >     ret = memory_failure(pfn, flags);
> >     if (!ret) {
> >             set_mce_nospec(pfn);
> >             sync_core();
> >             return;
> >     }
> >
> > Is this expected?
> >
>
> the second set_mce_nospec do nothing and have no side affect.
>
> sync_core() is introduced by Tony [1]:
>
> Also moved sync_core(). The comments for this function say that it should
> only be called when instructions have been changed/re-mapped. Recovery for
> an instruction fetch may change the physical address. But that doesn't happen
> until the scheduled work runs (which could be on another CPU).
>
> [1]https://lore.kernel.org/all/20200824221237.5397-1-tony.luck@intel.com/T/#u
>
> IMHO, I think it also has no side affect.
>
> @Tony, could you help to confirm this?

Correct. Re-runing these calls is harmless.

-Tony