Messages in this thread | | | From | KOSAKI Motohiro <> | Date | Tue, 7 May 2013 22:41:17 -0400 | Subject | Re: [PATCH] mm: honor FOLL_GET flag in follow_hugetlb_page v2 |
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On Tue, May 7, 2013 at 8:51 PM, Jerome Glisse <j.glisse@gmail.com> wrote: > On Tue, May 7, 2013 at 8:47 PM, KOSAKI Motohiro > <kosaki.motohiro@gmail.com> wrote: >> On Tue, May 7, 2013 at 6:58 PM, <j.glisse@gmail.com> wrote: >>> From: Jerome Glisse <jglisse@redhat.com> >>> >>> Do not increase page count if FOLL_GET is not set. None of the >>> current user can trigger the issue because none of the current >>> user call __get_user_pages with both the pages array ptr non >>> NULL and the FOLL_GET flags non set in other word all caller >>> of __get_user_pages that don't set the FOLL_GET flags also call >>> with pages == NULL. >> >> Because, __get_user_pages() doesn't allow pages==NULL and FOLL_GET is on. > > Yes but this allow pages != NULL and FOLL_GET not set and as i said > there is no such user of that yet and this is exactly what i was > trying to use.
Why? The following bug_on inhibit both case.
>> VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
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