lkml.org 
[lkml]   [2015]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [linux41] regression with 'x86/cacheinfo: Move cacheinfo sysfs code to generic infrastructure' on AMD i686
On Sun, Jul 26, 2015 at 10:13:45AM +0200, Thomas Gleixner wrote:
> On Sun, 26 Jul 2015, Philip Müller wrote:
> > > 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
>
> That's a trivial NULL pointer dereference in the error/cleanup
> path. Patch below should fix it.

Well, I got a bit different, and of course totally untested possible
solution:

cache_shared_cpu_map_setup() does check sib_cpu_ci->info_list before
setting cpumask bits while cache_shared_cpu_map_remove() doesn't. Ballancing
this out would mean:

---
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 764280a91776..8a4546dc25e3 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 */
continue;
+
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);
---
Now Philip can have some more fun testing :-)

--
Regards/Gruss,
Boris.

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


\
 
 \ /
  Last update: 2015-07-26 11:01    [W:0.117 / U:0.872 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site