On 2/5/20 5:43 PM, Mina Almasry wrote: > On Wed, Feb 5, 2020 at 3:57 PM Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: >> >> On 2/3/20 3:22 PM, Mina Almasry wrote: >>> A follow up patch in this series adds hugetlb cgroup uncharge info the >>> file_region entries in resv->regions. The cgroup uncharge info may >>> differ for different regions, so they can no longer be coalesced at >>> region_add time. So, disable region coalescing in region_add in this >>> patch. >>> >>> Behavior change: >>> >>> Say a resv_map exists like this [0->1], [2->3], and [5->6]. >>> >>> Then a region_chg/add call comes in region_chg/add(f=0, t=5). >>> >>> Old code would generate resv->regions: [0->5], [5->6]. >>> New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5], >>> [5->6]. >>> >>> Special care needs to be taken to handle the resv->adds_in_progress >>> variable correctly. In the past, only 1 region would be added for every >>> region_chg and region_add call. But now, each call may add multiple >>> regions, so we can no longer increment adds_in_progress by 1 in region_chg, >>> or decrement adds_in_progress by 1 after region_add or region_abort. Instead, >>> region_chg calls add_reservation_in_range() to count the number of regions >>> needed and allocates those, and that info is passed to region_add and >>> region_abort to decrement adds_in_progress correctly. >>> >>> We've also modified the assumption that region_add after region_chg >>> never fails. region_chg now pre-allocates at least 1 region for >>> region_add. If region_add needs more regions than region_chg has >>> allocated for it, then it may fail. >>> >>> Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx> >>> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> >> >> This is the same as the previous version. My late comment was that we >> need to rethink the disabling of region coalescing. This is especially >> important for private mappings where there will be one region for huge >> page. I know that you are working on this issue. Please remove my >> Reviewed-by: when sending out the next version. >> > > Yes to address that there is a new patch in the series, which > re-enables the coalescing when the hugetlb cgroup uncharge info is the > same. I guess it could be squashed with this one but I thought it was > better to implement that patch on top of the patch that enabled shared > accounting, because that is the patch that sets hugetlb cgroup info on > the file region entries. > > Let me know what you think. Thanks, I saw there was an additional patch but I did not get to it yet. I'll take a look and see how involved the changes are. -- Mike Kravetz
