From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 35D286B0031 for ; Tue, 15 Oct 2013 14:49:04 -0400 (EDT) Received: by mail-pa0-f43.google.com with SMTP id hz1so9471364pad.2 for ; Tue, 15 Oct 2013 11:49:03 -0700 (PDT) Received: by mail-vb0-f44.google.com with SMTP id p14so413537vbm.17 for ; Tue, 15 Oct 2013 11:49:00 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20131015110146.7E8BEE0090@blue.fi.intel.com> References: <20131015001304.GH3432@hippobay.mtv.corp.google.com> <20131015110146.7E8BEE0090@blue.fi.intel.com> From: Ning Qu Date: Tue, 15 Oct 2013 11:48:40 -0700 Message-ID: Subject: Re: [PATCH 07/12] mm, thp, tmpfs: handle huge page in shmem_undo_range for truncate Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Andrea Arcangeli , Andrew Morton , Hugh Dickins , Al Viro , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , Hillf Danton , Dave Hansen , Alexander Shishkin , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Best wishes, --=20 Ning Qu (=E6=9B=B2=E5=AE=81) | Software Engineer | quning@google.com | +1-4= 08-418-6066 On Tue, Oct 15, 2013 at 4:01 AM, Kirill A. Shutemov wrote: > Ning Qu wrote: >> When comes to truncate file, add support to handle huge page in the >> truncate range. >> >> Signed-off-by: Ning Qu >> --- >> mm/shmem.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++= ------- >> 1 file changed, 86 insertions(+), 11 deletions(-) >> >> diff --git a/mm/shmem.c b/mm/shmem.c >> index 0a423a9..90f2e0e 100644 >> --- a/mm/shmem.c >> +++ b/mm/shmem.c >> @@ -559,6 +559,7 @@ static void shmem_undo_range(struct inode *inode, lo= ff_t lstart, loff_t lend, >> struct shmem_inode_info *info =3D SHMEM_I(inode); >> pgoff_t start =3D (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHI= FT; >> pgoff_t end =3D (lend + 1) >> PAGE_CACHE_SHIFT; >> + /* Whether we have to do partial truncate */ >> unsigned int partial_start =3D lstart & (PAGE_CACHE_SIZE - 1); >> unsigned int partial_end =3D (lend + 1) & (PAGE_CACHE_SIZE - 1); >> struct pagevec pvec; >> @@ -570,12 +571,16 @@ static void shmem_undo_range(struct inode *inode, = loff_t lstart, loff_t lend, >> if (lend =3D=3D -1) >> end =3D -1; /* unsigned, so actually very big */ >> >> + i_split_down_read(inode); >> pagevec_init(&pvec, 0); >> index =3D start; >> while (index < end) { >> + bool thp =3D false; >> + >> pvec.nr =3D shmem_find_get_pages_and_swap(mapping, index, >> min(end - index, (pgoff_t)PAGEVEC_SIZE), >> pvec.pages, indice= s); >> + >> if (!pvec.nr) >> break; >> mem_cgroup_uncharge_start(); >> @@ -586,6 +591,25 @@ static void shmem_undo_range(struct inode *inode, l= off_t lstart, loff_t lend, >> if (index >=3D end) >> break; >> >> + thp =3D PageTransHugeCache(page); >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE > > Again. Here and below ifdef is redundant: PageTransHugeCache() is zero > compile-time and thp case will be optimize out. The problem is actually from HPAGE_CACHE_INDEX_MASK, it is marked as build bug when CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE is false. So we either wrap some logic inside a inline function, or we have to be like this .. Or we don't treat the HPAGE_CACHE_INDEX_MASK as a build bug? > > And do we really need a copy of truncate logic here? Is there a way to > share code? > The truncate between tmpfs and general one is similar but not exactly the same (no readahead), so share the whole function might not be a good choice from the perspective of tmpfs? Anyway, there are other similar functions in tmpfs, e.g. the one you mentioned for shmem_add_to_page_cache. It is possible to share the code, I am just worried it will make the logic more complicated? Maybe Hugh is in better position to judge on this? Thanks! > -- > Kirill A. Shutemov -- 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