Re: [PATCH] cpu/cacheinfo: Fix teardown path

From: Borislav Petkov
Date: Sat Aug 08 2015 - 04:46:42 EST

On Mon, Jul 27, 2015 at 09:58:05AM +0200, Borislav Petkov wrote:
> Philip MÃller 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:

Bah, this goes to Greg and not to tip. Anyway, here's a version with
updated tags.

Greg, please queue for 4.2 as it fixes a hang.


From: Borislav Petkov <bp@xxxxxxx>
Date: Mon, 27 Jul 2015 08:36:27 +0200
Subject: [PATCH] cpu/cacheinfo: Fix teardown path
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Philip MÃller 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-and-tested-by: Philip MÃller <philm@xxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 4.1
Cc: Andre Przywara <andre.przywara@xxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: manjaro-dev@xxxxxxxxxxx
Cc: Philip MÃller <philm@xxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
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.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at