On Fri, Mar 15, 2013 at 2:56 PM, Stephane Eranian <eran...@google.com> wrote: > On Fri, Mar 15, 2013 at 9:53 PM, Shuah Khan <shuahk...@gmail.com> wrote: >> On Fri, Mar 15, 2013 at 2:31 PM, Greg KH <gre...@linuxfoundation.org> wrote: >>> On Fri, Mar 15, 2013 at 02:26:07PM +0100, Stephane Eranian wrote: >>>> >>>> This patch fixes a kernel crash when using precise sampling (PEBS) >>>> after a suspend/resume. Turns out the CPU notifier code is not invoked >>>> on CPU0 (BP). Therefore, the DS_AREA (used by PEBS) is not restored >>>> properly >>>> by the kernel and keeps it power-on/resume value of 0 causing any PEBS >>>> measurement to crash when running on CPU0. >>>> >>>> The workaround is to add a hook in the actual resume code to restore >>>> the DS Area MSR value. It is invoked for all CPUS. So for all but CPU0, >>>> the DS_AREA will be restored twice but this is harmless. >>>> >>>> Reported-by: Linus Torvalds <torva...@linux-foundation.org> >>>> Signed-off-by: Stephane Eranian <eran...@google.com> >>>> --- >>> >>> Is this needed for the 3.8 or older kernels as well? >>> >>> thanks, >>> >>> greg k-h >> >> Just about to ask the same question. Patch applies to 3.8, 3.4, 3.2 >> and 3.5. But needs some massaging for 3.0. I have the kernels built, >> haven't started testing yet. >> > Testing the patch is easy: > > # echo mem >/sys/power/state > Then press the power button again, when you get control again, type: > > $ taskset -c 0 perf record -e cycles:pp my_test_program > > Note that this problem impacts only Intel processors after Core 2 > (PEBS enabled).
Thanks. Reproduced the problem on 3.8.3, 3.4.36, and 3.0.69. Tested the patch on 3.4 and 3.8 and the problem is fixed. I had to re-cut the patch for 3.0. Sending it to stable tagged for 3.0 Thanks, -- Shuah -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
