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From:   Zhiquan Li <zhiquan1.li@intel.com>
To:     x86@kernel.org, linux-edac@vger.kernel.org,
        linux-kernel@vger.kernel.org, patches@lists.linux.dev,
        tony.luck@intel.com, naoya.horiguchi@nec.com, bp@alien8.de
Cc:     youquan.song@intel.com, zhiquan1.li@intel.com
Subject: [PATCH v2] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic
Date:   Mon, 27 Mar 2023 10:33:58 +0800
Message-Id: <20230327023358.3191922-1-zhiquan1.li@intel.com>
MIME-Version: 1.0
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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@intel.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

---

Changes since V1:
- Rebased to latest tip/ras/core (based on v6.3-rc1).
- Revised the commit message as per Naoya's suggestion.
- Removed 'TODO' from comment, as previously discussed, there is nothing
  more to do at this time.
  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 7832a69d170e..dea393ca949b 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.
+ */
+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);
-- 
2.25.1