On 04/25/2018 02:52 PM, Roman Gushchin wrote: > On Wed, Apr 25, 2018 at 09:19:29AM +0530, Vijayanand Jitta wrote: >>>>>> Idk, I don't like the idea of adding a counter outside of the vm counters >>>>>> infrastructure, and I definitely wouldn't touch the exposed >>>>>> nr_slab_reclaimable and nr_slab_unreclaimable fields. >>>>> >>>>> We would be just making the reported values more precise wrt reality. >>>> >>>> It depends on if we believe that only slab memory can be reclaimable >>>> or not. If yes, this is true, otherwise not. >>>> >>>> My guess is that some drivers (e.g. networking) might have buffers, >>>> which are reclaimable under mempressure, and are allocated using >>>> the page allocator. But I have to look closer... >>>> >>> >>> One such case I have encountered is that of the ION page pool. The page pool >>> registers a shrinker. When not in any memory pressure page pool can go high >>> and thus cause an mmap to fail when OVERCOMMIT_GUESS is set. I can send >>> a patch to account ION page pool pages in NR_INDIRECTLY_RECLAIMABLE_BYTES. FYI, we have discussed this at LSF/MM and agreed to try the kmalloc reclaimable caches idea. The existing counter could then remain for page allocator users such as ION. It's a bit weird to have it in bytes and not pages then, IMHO. What if we hid it from /proc/vmstat now so it doesn't become ABI, and later convert it to page granularity and expose it under a name such as "nr_other_reclaimable" ? Vlastimil > Perfect! > This is exactly what I've expected. > >>> >>> Thanks, >>> Vinayak >>> >> >> As Vinayak mentioned NR_INDIRECTLY_RECLAIMABLE_BYTES can be used to solve the issue >> with ION page pool when OVERCOMMIT_GUESS is set, the patch for the same can be >> found here https://lkml.org/lkml/2018/4/24/1288 > > This makes perfect sense to me. > > Please, fell free to add: > Acked-by: Roman Gushchin <guro@xxxxxx> > > Thank you! >
