From: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>, "x86@kernel.org" <x86@kernel.org>,
"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"patches@lists.linux.dev" <patches@lists.linux.dev>,
"Li, Zhiquan1" <zhiquan1.li@intel.com>,
"Song, Youquan" <youquan.song@intel.com>
Subject: Re: [PATCH] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic
Date: Tue, 31 Jan 2023 04:50:12 +0000 [thread overview]
Message-ID: <20230131045011.GB3997492@hori.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <SJ1PR11MB6083B06E5B75E429E5143B76FCD39@SJ1PR11MB6083.namprd11.prod.outlook.com>
On Mon, Jan 30, 2023 at 07:21:15PM +0000, Luck, Tony wrote:
> > Although I'm not sure that SGX memory or PMEM pages are expected to be
> > included in kdump, but simply setting PageHWPoison does not work for them?
> > (Maybe that depends on how kdump handles these types of memory.)
>
> SGX/TDX pages can't be dumped. They are encrypted with no way for kdump to
> get the key.
>
> PMEM seems pointless (but I don't know what kdump does here).
>
> > As for HugeTLB, kdump utility should parse the struct page and be aware of
> > HugeTLB pages, so maybe setting PageHWPoison on the head page could work.
>
> Or maybe kdump can take not of the PageHWPoison flag on the sub-page of the
> huge page? It depends on whether there is any benefit to the dump to include the
> not-poisoned parts of a huge page.
I think that many kdump users filter out HugeTLB pages (setting dump_level
to filter "User pages") to reduce the size of kdump. User pages are not
much helpful to investigate kernel problems, so filtering all sub-pages in
hwpoisoned hugepage seems to me not so harmful.
I don't say that saving healthy subpages has no benefit, but I don't know
much about usecases where user pages in kdump file help.
Thanks,
Naoya Horiguchi
next prev parent reply other threads:[~2023-01-31 4:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-27 1:50 [PATCH] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic Tony Luck
2023-01-30 2:32 ` HORIGUCHI NAOYA(堀口 直也)
2023-01-30 19:21 ` Luck, Tony
2023-01-31 4:50 ` HORIGUCHI NAOYA(堀口 直也) [this message]
2023-02-01 2:47 ` Zhiquan Li
2023-07-19 21:16 ` [PATCH v2] " Tony Luck
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