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Date: Mon, 2 Oct 2023 21:06:12 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Zhiquan Li <zhiquan1.li@...el.com>
Cc: x86@...nel.org, linux-edac@...r.kernel.org,
linux-kernel@...r.kernel.org, patches@...ts.linux.dev,
bp@...en8.de, tony.luck@...el.com, naoya.horiguchi@....com,
Youquan Song <youquan.song@...el.com>
Subject: Re: [PATCH RESEND v2] x86/mce: Set PG_hwpoison page flag to avoid
the capture kernel panic
* Zhiquan Li <zhiquan1.li@...el.com> wrote:
> Kdump can exclude the HWPosion page to avoid touch the error page
> again, the prerequisite is the PG_hwpoison page flag is set.
> However, for some MCE fatal error cases, there is no opportunity
> to queue a task for calling memory_failure(), as a result,
> the capture kernel touches the error page again and panics.
>
> Add function mce_set_page_hwpoison_now() which marks a page as
> HWPoison before kernel panic() for MCE error, so that the dump
> program can check and skip the error page and prevent the capture
> kernel panic.
>
> [Tony: Changed TestSetPageHWPoison() to SetPageHWPoison()]
>
> Co-developed-by: Youquan Song <youquan.song@...el.com>
> Signed-off-by: Youquan Song <youquan.song@...el.com>
> Signed-off-by: Zhiquan Li <zhiquan1.li@...el.com>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@....com>
>
> ---
> V2 RESEND notes:
> - No changes on this, just rebasing as v6.6-rc1 is out.
> - Added the tag from Naoya.
> Link: https://lore.kernel.org/all/20230719211625.298785-1-tony.luck@intel.com/#t
>
> Changes since V1:
> - Revised the commit message as per Naoya's suggestion.
> - Replaced "TODO" comment in code with comments based on mailing list
> discussion on the lack of value in covering other page types.
> Link: https://lore.kernel.org/all/20230127015030.30074-1-tony.luck@intel.com/
> ---
> arch/x86/kernel/cpu/mce/core.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 6f35f724cc14..2725698268f3 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -156,6 +156,22 @@ void mce_unregister_decode_chain(struct notifier_block *nb)
> }
> EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
>
> +/*
> + * Kdump can exclude the HWPosion page to avoid touch the error page again,
> + * the prerequisite is the PG_hwpoison page flag is set. However, for some
> + * MCE fatal error cases, there are no opportunity to queue a task
> + * for calling memory_failure(), as a result, the capture kernel panics.
> + * This function marks the page as HWPoison before kernel panic() for MCE.
> + */
The English in this commit is *atrocious*, both in the changelog and in
the comments - how on Earth did 'Posion' typo and half a dozen other typos
and bad grammar survive ~3 iterations and a Reviewed-by tag??
The version below fixes up the worst, but I suspect that's not the only problem
with this patch...
Thanks,
Ingo
================>
From: Zhiquan Li <zhiquan1.li@...el.com>
Date: Thu, 14 Sep 2023 11:05:39 +0800
Subject: [PATCH] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic
Kdump can exclude the HWPoison page to avoid touching the error page
again, the prerequisite is the PG_hwpoison page flag is set.
However, for some MCE fatal error cases, there is no opportunity
to queue a task for calling memory_failure(), and as a result,
the capture kernel touches the error page again and panics.
Add the mce_set_page_hwpoison_now() function, which marks a page as
HWPoison before kernel panic() for MCE error, so that the dump
program can check and skip the error page and prevent the capture
kernel panic.
[ Tony: Changed TestSetPageHWPoison() to SetPageHWPoison() ]
[ mingo: Fixed the comments & changelog ]
Co-developed-by: Youquan Song <youquan.song@...el.com>
Signed-off-by: Youquan Song <youquan.song@...el.com>
Signed-off-by: Zhiquan Li <zhiquan1.li@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@....com>
Cc: Borislav Petkov <bp@...en8.de>
Link: https://lore.kernel.org/all/20230719211625.298785-1-tony.luck@intel.com/#t
---
arch/x86/kernel/cpu/mce/core.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 6f35f724cc14..1a14e8233c5a 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -156,6 +156,22 @@ void mce_unregister_decode_chain(struct notifier_block *nb)
}
EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
+/*
+ * Kdump can exclude the HWPoison page to avoid touching the error page again,
+ * the prerequisite is that the PG_hwpoison page flag is set. However, for some
+ * MCE fatal error cases, there is no opportunity to queue a task
+ * for calling memory_failure(), and as a result, the capture kernel panics.
+ * This function marks the page as HWPoison before kernel panic() for MCE.
+ */
+static void mce_set_page_hwpoison_now(unsigned long pfn)
+{
+ struct page *p;
+
+ p = pfn_to_online_page(pfn);
+ if (p)
+ SetPageHWPoison(p);
+}
+
static void __print_mce(struct mce *m)
{
pr_emerg(HW_ERR "CPU %d: Machine Check%s: %Lx Bank %d: %016Lx\n",
@@ -286,6 +302,8 @@ static noinstr void mce_panic(const char *msg, struct mce *final, char *exp)
if (!fake_panic) {
if (panic_timeout == 0)
panic_timeout = mca_cfg.panic_timeout;
+ if (final && (final->status & MCI_STATUS_ADDRV))
+ mce_set_page_hwpoison_now(final->addr >> PAGE_SHIFT);
panic(msg);
} else
pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg);
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