On Mon, Feb 03, 2014 at 02:20:01PM +0100, Michal Hocko wrote: > On Thu 30-01-14 12:18:37, Johannes Weiner wrote: > > On Tue, Dec 17, 2013 at 04:45:26PM +0100, Michal Hocko wrote: > [...] > > > -static int __mem_cgroup_try_charge(struct mm_struct *mm, > > > - gfp_t gfp_mask, > > > +static int __mem_cgroup_try_charge_memcg(gfp_t gfp_mask, > > > unsigned int nr_pages, > > > - struct mem_cgroup **ptr, > > > + struct mem_cgroup *memcg, > > > bool oom) > > > > Why not keep the __mem_cgroup_try_charge() name? It's shorter and > > just as descriptive. > > I wanted to have 2 different names with clear reference to _what_ is > going to be charged. But I am always open to naming suggestions. > > > > +/* > > > + * Charges and returns memcg associated with the given mm (or root_mem_cgroup > > > + * if mm is NULL). Returns NULL if memcg is under OOM. > > > + */ > > > +static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm, > > > + gfp_t gfp_mask, > > > + unsigned int nr_pages, > > > + bool oom) > > > > We already have a try_get_mem_cgroup_from_mm(). > > > > After this series, this function basically duplicates that and it > > would be much cleaner if we only had one try_charge() function and let > > all the callers use the appropriate try_get_mem_cgroup_from_wherever() > > themselves. > > try_get_mem_cgroup_from_mm doesn't charge memory itself. It just tries > to get memcg from the given mm. It is called also from a context which > doesn't charge any memory (task_in_mem_cgroup). Or have I misunderstood > you? Your mem_cgroup_try_charge_mm() looks up a memcg from mm and calls try_charge(). But we have try_get_mem_cgroup_from_mm() to do the first half, so why not have the current callers of mem_cgroup_try_charge_mm() just use try_get_mem_cgroup_from_mm() and try_charge()? Why is charging through an mm - as opposed to through a page or through the task - special? Most callsites already do the lookups themselves: try_charge_swapin: uses try_get_mem_cgroup_from_page() kmem_newpage_charge: uses try_get_mem_cgroup_from_mm() precharge: uses mem_cgroup_from_task() So just let these two do the same: newpage_charge: could use try_get_mem_cgroup_from_mm() cache_charge: could use try_get_mem_cgroup_from_mm() And then provide one try_charge() that always takes a non-null memcg. -- 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>