On Mon 03-02-14 11:18:23, Johannes Weiner wrote: > On Mon, Feb 03, 2014 at 02:33:13PM +0100, Michal Hocko wrote: > > On Thu 30-01-14 12:29:06, Johannes Weiner wrote: > > > On Tue, Dec 17, 2013 at 04:45:29PM +0100, Michal Hocko wrote: [...] > > > > In order to make this raceless we would need to hold rcu_read_lock since > > > > css_tryget until res_counter_charge. This is not so easy unfortunately > > > > because mem_cgroup_do_charge might sleep so we would need to do drop rcu > > > > lock and do css_tryget tricks after each reclaim. > > > > > > Yes, why not? > > > > Although css_tryget is cheap these days I thought that a simple flag > > check would be even heaper in this hot path. Changing the patch to use > > css_tryget rather than offline check is trivial if you really think it > > is better? > > You already changed it to do css_tryget() on every single charge. Fair point Thanks! -- Michal Hocko SUSE Labs -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>