From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id BCB2F6B3F57 for ; Mon, 27 Aug 2018 03:46:49 -0400 (EDT) Received: by mail-ed1-f70.google.com with SMTP id m9-v6so941158eds.17 for ; Mon, 27 Aug 2018 00:46:49 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id n52-v6si3406279edn.367.2018.08.27.00.46.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Aug 2018 00:46:48 -0700 (PDT) Date: Mon, 27 Aug 2018 09:46:45 +0200 From: Michal Hocko Subject: Re: [PATCH v6 1/2] mm: migration: fix migration of huge PMD shared pages Message-ID: <20180827074645.GB21556@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6063f215-a5c8-2f0c-465a-2c515ddc952d@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" , =?iso-8859-1?B?Suly9G1l?= Glisse , Vlastimil Babka , Naoya Horiguchi , Davidlohr Bueso , Andrew Morton , stable@vger.kernel.org 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). -- Michal Hocko SUSE Labs