[manjaro-dev] [PATCH] cpu/cacheinfo: Fix teardown path

Borislav Petkov bp at suse.de
Mon Jul 27 09:58:05 CEST 2015

From: Borislav Petkov <bp at suse.de>
Date: Mon, 27 Jul 2015 08:36:27 +0200
Subject: [PATCH] cpu/cacheinfo: Fix teardown path
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Philip Müller reported a hang when booting 32-bit 4.1 kernel on an AMD
box. A fragment of the splat was enough to pinpoint the issue:

  task: f58e0000 ti: f58e8000 task.ti: f58e800
  EIP: 0060:[<c135a903>] EFLAGS: 00010206 CPU: 0
  EIP is at free_cache_attributes+0x83/0xd0
  EAX: 00000001 EBX: f589d46c ECX: 00000090 EDX: 360c2000
  ESI: 00000000 EDI: c1724a80 EBP: f58e9ec0 ESP: f58e9ea0
   DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
  CR0: 8005003b CR2: 000000ac CR3: 01731000 CR4: 000006d0

cache_shared_cpu_map_setup() did check sibling CPUs cacheinfo descriptor
while the respective teardown path cache_shared_cpu_map_remove() didn't.
Fix that.

>From tglx's version: to be on the safe side, move the cacheinfo
descriptor check to free_cache_attributes(), thus cleaning up the
hotplug path a little and making this even more robust.

Reported-by: Philip Müller <philm at manjaro.org>
Cc: <stable at vger.kernel.org> # 4.1
Cc: Andre Przywara <andre.przywara at arm.com>
Cc: Guenter Roeck <linux at roeck-us.net>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: linux-kernel at vger.kernel.org
Cc: manjaro-dev at manjaro.org
Cc: Philip Müller <philm at manjaro.org>
Cc: Sudeep Holla <sudeep.holla at arm.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Link: https://lkml.kernel.org/r/55B47BB8.6080202@manjaro.org
Signed-off-by: Borislav Petkov <bp at suse.de>

Moin Thomas,

I've merged both patches and tagged it for stable. Which means,


 drivers/base/cacheinfo.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 764280a91776..e9fd32e91668 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -148,7 +148,11 @@ static void cache_shared_cpu_map_remove(unsigned int cpu)
 			if (sibling == cpu) /* skip itself */
 			sib_cpu_ci = get_cpu_cacheinfo(sibling);
+			if (!sib_cpu_ci->info_list)
+				continue;
 			sib_leaf = sib_cpu_ci->info_list + index;
 			cpumask_clear_cpu(cpu, &sib_leaf->shared_cpu_map);
 			cpumask_clear_cpu(sibling, &this_leaf->shared_cpu_map);
@@ -159,6 +163,9 @@ static void cache_shared_cpu_map_remove(unsigned int cpu)
 static void free_cache_attributes(unsigned int cpu)
+	if (!per_cpu_cacheinfo(cpu))
+		return;
@@ -514,8 +521,7 @@ static int cacheinfo_cpu_callback(struct notifier_block *nfb,
 	case CPU_DEAD:
-		if (per_cpu_cacheinfo(cpu))
-			free_cache_attributes(cpu);
+		free_cache_attributes(cpu);
 	return notifier_from_errno(rc);


ECO tip #101: Trim your mails when you reply.

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