The patch titled
Subject: mm/hwpoison: fix incorrect "not recovered" report for recovered clean pages
has been added to the -mm mm-unstable branch. Its filename is
mm-hwpoison-fix-incorrect-not-recovered-report-for-recovered-clean-pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hwpoison-fix-incorrect-not-recovered-report-for-recovered-clean-pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
Subject: mm/hwpoison: fix incorrect "not recovered" report for recovered clean pages
Date: Mon, 17 Feb 2025 14:33:34 +0800
When an uncorrected memory error is consumed there is a race between the
CMCI from the memory controller reporting an uncorrected error with a UCNA
signature, and the core reporting and SRAR signature machine check when
the data is about to be consumed.
If the CMCI wins that race, the page is marked poisoned when
uc_decode_notifier() calls memory_failure(). For dirty pages,
memory_failure() invokes try_to_unmap() with the TTU_HWPOISON flag,
converting the PTE to a hwpoison entry. As a result,
kill_accessing_process():
- call walk_page_range() and return 1 regardless of whether
try_to_unmap() succeeds or fails,
- call kill_proc() to make sure a SIGBUS is sent
- return -EHWPOISON to indicate that SIGBUS is already sent to the
process and kill_me_maybe() doesn't have to send it again.
However, for clean pages, the TTU_HWPOISON flag is cleared, leaving the
PTE unchanged and not converted to a hwpoison entry. Conversely, for
clean pages where PTE entries are not marked as hwpoison,
kill_accessing_process() returns -EFAULT, causing kill_me_maybe() to send
a SIGBUS.
Console log looks like this:
Memory failure: 0x827ca68: corrupted page was clean: dropped without side effects
Memory failure: 0x827ca68: recovery action for clean LRU page: Recovered
Memory failure: 0x827ca68: already hardware poisoned
mce: Memory error not recovered
To fix it, return 0 for "corrupted page was clean", preventing an
unnecessary SIGBUS.
Link: https://lkml.kernel.org/r/20250217063335.22257-5-xueshuai@xxxxxxxxxxxxxxxxx
Fixes: 046545a661af ("mm/hwpoison: fix error page recovered but reported "not recovered"")
Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Acked-by:Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Borislav Betkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jane Chu <jane.chu@xxxxxxxxxx>
Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: linmiaohe <linmiaohe@xxxxxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Cc: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ruidong Tian <tianruidong@xxxxxxxxxxxxxxxxx>
Cc: Yazen Ghannam <yazen.ghannam@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/mm/memory-failure.c~mm-hwpoison-fix-incorrect-not-recovered-report-for-recovered-clean-pages
+++ a/mm/memory-failure.c
@@ -881,12 +881,17 @@ static int kill_accessing_process(struct
mmap_read_lock(p->mm);
ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwpoison_walk_ops,
(void *)&priv);
+ /*
+ * ret = 1 when CMCI wins, regardless of whether try_to_unmap()
+ * succeeds or fails, then kill the process with SIGBUS.
+ * ret = 0 when poison page is a clean page and it's dropped, no
+ * SIGBUS is needed.
+ */
if (ret == 1 && priv.tk.addr)
kill_proc(&priv.tk, pfn, flags);
- else
- ret = 0;
mmap_read_unlock(p->mm);
- return ret > 0 ? -EHWPOISON : -EFAULT;
+
+ return ret > 0 ? -EHWPOISON : 0;
}
/*
_
Patches currently in -mm which might be from xueshuai@xxxxxxxxxxxxxxxxx are
x86-mce-collect-error-message-for-severities-below-mce_panic_severity.patch
x86-mce-dump-error-msg-from-severities.patch
x86-mce-add-ex_type_efault_reg-as-in-kernel-recovery-context-to-fix-copy-from-user-operations-regression.patch
mm-hwpoison-fix-incorrect-not-recovered-report-for-recovered-clean-pages.patch
mm-memory-failure-move-return-value-documentation-to-function-declaration.patch
