linux-kernel - [PATCH 1/2] x86, perf: Remove warning for zero PEBS status

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Message-Id: <1449177740-5422-1-git-send-email-andi@firstfloor.org>
Date:	Thu,  3 Dec 2015 13:22:19 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	peterz@...radead.org
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 1/2] x86, perf: Remove warning for zero PEBS status

From: Andi Kleen <ak@...ux.intel.com>

The recent change 75f80859b1 (... Robustify PEBS buffer drain)
causes lots of warnings on different CPUs before Skylake
when running PEBS intensive workloads.

They can have a zero status field in the PEBS record when
PEBS is racing with clearing of GLOBAl_STATUS.

This also can cause hangs (it seems there are still
problems with printk in NMI)

Disable the warning, but still ignore the record.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/kernel/cpu/perf_event_intel_ds.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 7f11784..da294de 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -1237,10 +1237,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
 
 		bit = find_first_bit((unsigned long *)&pebs_status,
 					x86_pmu.max_pebs_events);
-		if (WARN(bit >= x86_pmu.max_pebs_events,
-			 "PEBS record without PEBS event! status=%Lx pebs_enabled=%Lx active_mask=%Lx",
-			 (unsigned long long)p->status, (unsigned long long)cpuc->pebs_enabled,
-			 *(unsigned long long *)cpuc->active_mask))
+		if (bit >= x86_pmu.max_pebs_events)
 			continue;
 
 		/*
-- 
2.4.3

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