From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id E80EB6B3D25 for ; Mon, 27 Aug 2018 09:46:37 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id u45-v6so15373098qte.12 for ; Mon, 27 Aug 2018 06:46:37 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id t23-v6si5847820qtt.278.2018.08.27.06.46.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Aug 2018 06:46:37 -0700 (PDT) Date: Mon, 27 Aug 2018 09:46:33 -0400 From: Jerome Glisse Subject: Re: [PATCH v6 1/2] mm: migration: fix migration of huge PMD shared pages Message-ID: <20180827134633.GB3930@redhat.com> References: <20180823205917.16297-1-mike.kravetz@oracle.com> <20180823205917.16297-2-mike.kravetz@oracle.com> <20180824084157.GD29735@dhcp22.suse.cz> <6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com> <20180827074645.GB21556@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180827074645.GB21556@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" , Vlastimil Babka , Naoya Horiguchi , Davidlohr Bueso , Andrew Morton , stable@vger.kernel.org On Mon, Aug 27, 2018 at 09:46:45AM +0200, Michal Hocko wrote: > On Fri 24-08-18 11:08:24, Mike Kravetz wrote: > > On 08/24/2018 01:41 AM, Michal Hocko wrote: > > > On Thu 23-08-18 13:59:16, Mike Kravetz wrote: > > > > > > Acked-by: Michal Hocko > > > > > > One nit below. > > > > > > [...] > > >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > >> index 3103099f64fd..a73c5728e961 100644 > > >> --- a/mm/hugetlb.c > > >> +++ b/mm/hugetlb.c > > >> @@ -4548,6 +4548,9 @@ static unsigned long page_table_shareable(struct vm_area_struct *svma, > > >> return saddr; > > >> } > > >> > > >> +#define _range_in_vma(vma, start, end) \ > > >> + ((vma)->vm_start <= (start) && (end) <= (vma)->vm_end) > > >> + > > > > > > static inline please. Macros and potential side effects on given > > > arguments are just not worth the risk. I also think this is something > > > for more general use. We have that pattern at many places. So I would > > > stick that to linux/mm.h > > > > Thanks Michal, > > > > Here is an updated patch which does as you suggest above. > [...] > > @@ -1409,6 +1419,32 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, > > subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); > > address = pvmw.address; > > > > + if (PageHuge(page)) { > > + if (huge_pmd_unshare(mm, &address, pvmw.pte)) { > > + /* > > + * huge_pmd_unshare unmapped an entire PMD > > + * page. There is no way of knowing exactly > > + * which PMDs may be cached for this mm, so > > + * we must flush them all. start/end were > > + * already adjusted above to cover this range. > > + */ > > + flush_cache_range(vma, start, end); > > + flush_tlb_range(vma, start, end); > > + mmu_notifier_invalidate_range(mm, start, end); > > + > > + /* > > + * The ref count of the PMD page was dropped > > + * which is part of the way map counting > > + * is done for shared PMDs. Return 'true' > > + * here. When there is no other sharing, > > + * huge_pmd_unshare returns false and we will > > + * unmap the actual page and drop map count > > + * to zero. > > + */ > > + page_vma_mapped_walk_done(&pvmw); > > + break; > > + } > > This still calls into notifier while holding the ptl lock. Either I am > missing something or the invalidation is broken in this loop (not also > for other invalidations). mmu_notifier_invalidate_range() is done with pt lock held only the start and end versions need to happen outside pt lock. Cheers, Jerome