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Date: Wed, 1 Nov 2017 13:59:06 -0500 From: Yazen Ghannam <Yazen.Ghannam@....com> To: linux-edac@...r.kernel.org Cc: Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>, x86@...nel.org, linux-kernel@...r.kernel.org Subject: [PATCH v2] x86/MCE/AMD: Always give PANIC severity for UC errors IN_KERNEL context From: Yazen Ghannam <yazen.ghannam@....com> The AMD severity grading function was introduced in v4.1 and has remained logically unchanged with the exception of a separate SMCA severity grading function for SMCA systems. The current logic can possibly give MCE_AR_SEVERITY for uncorrectable errors in kernel context. The system may then get stuck in a loop as memory_failure() will try to handle the bad kernel memory and find it busy. Return MCE_PANIC_SEVERITY for all UC errors IN_KERNEL context on AMD systems. After: b2f9d678e28c ("x86/mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries") was accepted in v4.6, this issue was masked because of the tail-end attempt at kernel mode recovery in the #MC handler. However, uncorrectable errors IN_KERNEL context should always be considered unrecoverable and cause a panic. Fixes: bf80bbd7dcf5 (x86/mce: Add an AMD severities-grading function) Signed-off-by: Yazen Ghannam <yazen.ghannam@....com> [ This needs to be reworked to apply to v4.1 and v4.4 stable branches.] Cc: <stable@...r.kernel.org> # 4.9.x --- Link: https://lkml.kernel.org/r/1505830031-9630-1-git-send-email-Yazen.Ghannam@amd.com v1->v2: * Update commit message. arch/x86/kernel/cpu/mcheck/mce-severity.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce-severity.c b/arch/x86/kernel/cpu/mcheck/mce-severity.c index 2773c8547f69..f5518706baa6 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-severity.c +++ b/arch/x86/kernel/cpu/mcheck/mce-severity.c @@ -245,6 +245,9 @@ static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_exc if (m->status & MCI_STATUS_UC) { + if (ctx == IN_KERNEL) + return MCE_PANIC_SEVERITY; + /* * On older systems where overflow_recov flag is not present, we * should simply panic if an error overflow occurs. If @@ -255,10 +258,6 @@ static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_exc if (mce_flags.smca) return mce_severity_amd_smca(m, ctx); - /* software can try to contain */ - if (!(m->mcgstatus & MCG_STATUS_RIPV) && (ctx == IN_KERNEL)) - return MCE_PANIC_SEVERITY; - /* kill current process */ return MCE_AR_SEVERITY; } else { -- 2.7.4
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