From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 4/6] mm: introduce page->dma_pinned_flags, _count To: Michal Hocko CC: Jan Kara , Dave Chinner , Matthew Wilcox , Christopher Lameter , Jason Gunthorpe , Dan Williams , , Andrew Morton , LKML , linux-rdma , References: <20181012060014.10242-1-jhubbard@nvidia.com> <20181012060014.10242-5-jhubbard@nvidia.com> <20181013035516.GA18822@dastard> <7c2e3b54-0b1d-6726-a508-804ef8620cfd@nvidia.com> <20181013230124.GB18822@dastard> <20181016085102.GB18918@quack2.suse.cz> <20181017110952.GN18839@dhcp22.suse.cz> From: John Hubbard Message-ID: <2367ff26-809c-da94-a8f0-e921bdc4862a@nvidia.com> Date: Wed, 17 Oct 2018 17:03:03 -0700 MIME-Version: 1.0 In-Reply-To: <20181017110952.GN18839@dhcp22.suse.cz> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: On 10/17/18 4:09 AM, Michal Hocko wrote: > On Tue 16-10-18 18:48:23, John Hubbard wrote: > [...] >> It's hard to say exactly what the active/inactive/unevictable list should >> be when DMA is done and put_user_page*() is called, because we don't know >> if some device read, wrote, or ignored any of those pages. Although if >> put_user_pages_dirty() is called, that's an argument for "active", at least. > > Any reason to not use putback_lru_page? That does help with which LRU to use. I guess I'd still need to track whether a page was on an LRU when get_user_pages() was called, because it seems that that is not necessarily always the case. And putback_lru_page() definitely wants to deal with a page that *was* previously on an LRU. > > Please note I haven't really got through your patches to have a wider > picture of the change so this is just hint for the LRU part of the > issue. > Understood, and the hints are much appreciated. -- thanks, John Hubbard NVIDIA