[tip: x86/mm] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic

[tip-bot2 for Zhiquan Li]

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     cb17fd1dcdaea8f6508844c690b3ffd5da484800
Gitweb:        https://git.kernel.org/tip/cb17fd1dcdaea8f6508844c690b3ffd5da484800
Author:        Zhiquan Li <zhiquan1.li@xxxxxxxxx>
AuthorDate:    Thu, 14 Sep 2023 11:05:39 +08:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 02 Oct 2023 20:26:13 +02:00

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@xxxxxxxxx>
Signed-off-by: Youquan Song <youquan.song@xxxxxxxxx>
Signed-off-by: Zhiquan Li <zhiquan1.li@xxxxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Link: https://lore.kernel.org/all/20230719211625.298785-1-tony.luck@xxxxxxxxx/#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 6f35f72..1a14e82 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);