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Fri, 18 Dec 2020 04:33:12 -0800 (PST) MIME-Version: 1.0 References: <20201217185243.3288048-1-pasha.tatashin@soleen.com> <20201217185243.3288048-8-pasha.tatashin@soleen.com> <20201218095058.GV32193@dhcp22.suse.cz> In-Reply-To: <20201218095058.GV32193@dhcp22.suse.cz> From: Pavel Tatashin Date: Fri, 18 Dec 2020 07:32:36 -0500 Message-ID: Subject: Re: [PATCH v4 07/10] mm/gup: change index type to long as it counts pages To: Michal Hocko Cc: LKML , linux-mm , Andrew Morton , Vlastimil Babka , David Hildenbrand , Oscar Salvador , Dan Williams , Sasha Levin , Tyler Hicks , Joonsoo Kim , mike.kravetz@oracle.com, Steven Rostedt , Ingo Molnar , Jason Gunthorpe , Peter Zijlstra , Mel Gorman , Matthew Wilcox , David Rientjes , John Hubbard , Linux Doc Mailing List , Ira Weiny , linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Dec 18, 2020 at 4:51 AM Michal Hocko wrote: > > On Thu 17-12-20 13:52:40, Pavel Tatashin wrote: > > In __get_user_pages_locked() i counts number of pages which should be > > long. > > Do we know of any caller who would like to pin so many pages it wouldn't > fit into an int? I suspect this is more to sync types of nr_pages and > the iterator right. It would be better to be explicit about this in the > changelog. It is to sync types. I will add it to the changelog. But, in general 32-bit increasingly becomes too small for handling page count proportional values. It is 8T for npages. For pinning may be a bit too large today, but I can image RDMA this size in the future. > > > Signed-off-by: Pavel Tatashin > > Acked-by: Michal Hocko > > > --- > > mm/gup.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/gup.c b/mm/gup.c > > index 591d8e2dfc70..1ebb7cc2fbe4 100644 > > --- a/mm/gup.c > > +++ b/mm/gup.c > > @@ -1481,7 +1481,7 @@ static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start, > > { > > struct vm_area_struct *vma; > > unsigned long vm_flags; > > - int i; > > + long i; > > > > /* calculate required read or write permissions. > > * If FOLL_FORCE is set, we only require the "MAY" flags. > > -- > > 2.25.1 > > -- > Michal Hocko > SUSE Labs