2023-03-27 02:42:10

by Zhiquan Li

Subject: [PATCH v2] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic

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 <[email protected]>
Signed-off-by: Youquan Song <[email protected]>
Signed-off-by: Zhiquan Li <[email protected]>
Signed-off-by: Tony Luck <[email protected]>

---

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/[email protected]/
---
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

2023-03-27 08:43:16

by HORIGUCHI NAOYA(堀口　直也)

Subject: Re: [PATCH v2] x86/mce: Set PG_hwpoison page flag to avoid the capture kernel panic

On Mon, Mar 27, 2023 at 10:33:58AM +0800, Zhiquan Li 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 <[email protected]>
> Signed-off-by: Youquan Song <[email protected]>
> Signed-off-by: Zhiquan Li <[email protected]>
> Signed-off-by: Tony Luck <[email protected]>

Looks good to me, thank you.

Reviewed-by: Naoya Horiguchi <[email protected]>