From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id B937D6B0038 for ; Wed, 19 Nov 2014 04:10:36 -0500 (EST) Received: by mail-pa0-f45.google.com with SMTP id lj1so187998pab.18 for ; Wed, 19 Nov 2014 01:10:36 -0800 (PST) Received: from tyo202.gate.nec.co.jp (TYO202.gate.nec.co.jp. [210.143.35.52]) by mx.google.com with ESMTPS id sl5si1664937pbc.164.2014.11.19.01.10.34 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 19 Nov 2014 01:10:35 -0800 (PST) From: Naoya Horiguchi Subject: Re: [PATCH 17/19] mlock, thp: HACK: split all pages in VM_LOCKED vma Date: Wed, 19 Nov 2014 09:02:42 +0000 Message-ID: <20141119090318.GA3974@hori1.linux.bs1.fc.nec.co.jp> References: <1415198994-15252-1-git-send-email-kirill.shutemov@linux.intel.com> <1415198994-15252-18-git-send-email-kirill.shutemov@linux.intel.com> In-Reply-To: <1415198994-15252-18-git-send-email-kirill.shutemov@linux.intel.com> Content-Language: ja-JP Content-Type: text/plain; charset="iso-2022-jp" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Andrew Morton , Andrea Arcangeli , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" On Wed, Nov 05, 2014 at 04:49:52PM +0200, Kirill A. Shutemov wrote: > We don't yet handle mlocked pages properly with new THP refcounting. > For now we split all pages in VMA on mlock and disallow khugepaged > collapse pages in the VMA. If split failed on mlock() we fail the > syscall with -EBUSY. > --- ... > @@ -542,6 +530,60 @@ next: > } > } > =20 > +static int thp_split(pmd_t *pmd, unsigned long addr, unsigned long end, > + struct mm_walk *walk) > +{ > + spinlock_t *ptl; > + struct page *page =3D NULL; > + pte_t *pte; > + int err =3D 0; > + > +retry: > + if (pmd_none(*pmd)) > + return 0; > + if (pmd_trans_huge(*pmd)) { > + if (is_huge_zero_pmd(*pmd)) { > + split_huge_pmd(walk->vma, pmd, addr); > + return 0; > + } > + ptl =3D pmd_lock(walk->mm, pmd); > + if (!pmd_trans_huge(*pmd)) { > + spin_unlock(ptl); > + goto retry; > + } > + page =3D pmd_page(*pmd); > + VM_BUG_ON_PAGE(!PageHead(page), page); > + get_page(page); > + spin_unlock(ptl); > + err =3D split_huge_page(page); > + put_page(page); > + return err; > + } > + pte =3D pte_offset_map_lock(walk->mm, pmd, addr, &ptl); > + do { > + if (!pte_present(*pte)) > + continue; > + page =3D vm_normal_page(walk->vma, addr, *pte); > + if (!page) > + continue; > + if (PageTransCompound(page)) { > + page =3D compound_head(page); > + get_page(page); > + spin_unlock(ptl); > + err =3D split_huge_page(page); > + spin_lock(ptl); > + put_page(page); > + if (!err) { > + VM_BUG_ON_PAGE(compound_mapcount(page), page); > + VM_BUG_ON_PAGE(PageTransCompound(page), page); If split_huge_page() succeeded, we don't have to continue the iteration, so break this loop here? Thanks, Naoya Horiguchi > + } else > + break; > + } > + } while (pte++, addr +=3D PAGE_SIZE, addr !=3D end); > + pte_unmap_unlock(pte - 1, ptl); > + return err; > +} > + > /* > * mlock_fixup - handle mlock[all]/munlock[all] requests. > *= -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org