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x86/mce: Mark fatal MCE's page as poison to avoid panic in the kdump kernel

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[ Upstream commit 9f3b130048 ]

Memory errors don't happen very often, especially fatal ones. However,
in large-scale scenarios such as data centers, that probability
increases with the amount of machines present.

When a fatal machine check happens, mce_panic() is called based on the
severity grading of that error. The page containing the error is not
marked as poison.

However, when kexec is enabled, tools like makedumpfile understand when
pages are marked as poison and do not touch them so as not to cause
a fatal machine check exception again while dumping the previous
kernel's memory.

Therefore, mark the page containing the error as poisoned so that the
kexec'ed kernel can avoid accessing the page.

  [ bp: Rewrite commit message and comment. ]

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: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Link: https://lore.kernel.org/r/20231014051754.3759099-1-zhiquan1.li@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Zhiquan Li 2023-10-26 08:39:03 +08:00 committed by Greg Kroah-Hartman
parent 28b8ba8eeb
commit 04c6948db0
1 changed files with 16 additions and 0 deletions
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16
arch/x86/kernel/cpu/mce/core.c
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@ -44,6 +44,7 @@
#include <linux/sync_core.h>
#include <linux/task_work.h>
#include <linux/hardirq.h>
#include <linux/kexec.h>
#include <asm/intel-family.h>
#include <asm/processor.h>
@ -233,6 +234,7 @@ static noinstr void mce_panic(const char *msg, struct mce *final, char *exp)
struct llist_node *pending;
struct mce_evt_llist *l;
int apei_err = 0;
struct page *p;
/*
* Allow instrumentation around external facilities usage. Not that it
@ -286,6 +288,20 @@ 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;
/*
* Kdump skips the poisoned page in order to avoid
* touching the error bits again. Poison the page even
* if the error is fatal and the machine is about to
* panic.
*/
if (kexec_crash_loaded()) {
if (final && (final->status & MCI_STATUS_ADDRV)) {
p = pfn_to_online_page(final->addr >> PAGE_SHIFT);
if (p)
SetPageHWPoison(p);
}
}
panic(msg);
} else
pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg);