On Wed, Apr 04, 2012 at 02:34:03PM -0700, Andrew Morton wrote: > On Sat, 24 Dec 2011 05:00:18 +0200 > "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote: > > > From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> > > > > action != CPU_DEAD || action != CPU_DEAD_FROZEN is always true. > > > > Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> > > --- > > mm/memcontrol.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index b27ce0f..3833a7b 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -2100,7 +2100,7 @@ static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb, > > return NOTIFY_OK; > > } > > > > - if ((action != CPU_DEAD) || action != CPU_DEAD_FROZEN) > > + if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) > > return NOTIFY_OK; > > > > for_each_mem_cgroup(iter) > > This spent too long in the backlog, sorry. > > I don't want to merge this patch into either mainline or -stable until > I find out what it does! > > afacit the patch will newly cause the kernel to drain various resource > counters away from the target CPU when the CPU_DEAD or CPU_DEAD_FROZEN > events occur for thet CPU, yes? Yes. > So the user-visible effects of the bug whcih was just fixed is that > these counters will be somewhat inaccurate after a CPU is taken down, > yes? Correct. > Why wasn't this bug noticed before? I guess CPU hotplug is not a usual test case for memcg changes. And the result of the bug is inaccurate statistics, but not something dramatic (oops, panic, etc.). > Has anyone tested the patch and > confirmed that the numbers are now correct? I haven't. I found the bug with sparse. > Given that this bug has been present for 1.5 years and nobody noticed, > I don't think a backport into -stable is warranted? > -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>