From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 19 Oct 2018 10:11:15 +0200 From: Michal Hocko To: John Hubbard Cc: Jan Kara , Dave Chinner , Matthew Wilcox , Christopher Lameter , Jason Gunthorpe , Dan Williams , linux-mm@kvack.org, Andrew Morton , LKML , linux-rdma , linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 4/6] mm: introduce page->dma_pinned_flags, _count Message-ID: <20181019081115.GM18839@dhcp22.suse.cz> 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> <2367ff26-809c-da94-a8f0-e921bdc4862a@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2367ff26-809c-da94-a8f0-e921bdc4862a@nvidia.com> Sender: owner-linux-mm@kvack.org List-ID: On Wed 17-10-18 17:03:03, John Hubbard wrote: > 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. Well, if you ever g-u-p pages which are never going to go to LRU then sure (e.g. hugetlb pages). -- Michal Hocko SUSE Labs