Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934012Ab3FSBXZ (ORCPT ); Tue, 18 Jun 2013 21:23:25 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:36568 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933885Ab3FSBXW (ORCPT ); Tue, 18 Jun 2013 21:23:22 -0400 Message-ID: <51C107E9.9050900@huawei.com> Date: Wed, 19 Jun 2013 09:22:49 +0800 From: Jianguo Wu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Joern Engel CC: , , Andrew Morton Subject: Re: [PATCH 2/2] mmap: allow MAP_HUGETLB for hugetlbfs files References: <1371581225-27535-1-git-send-email-joern@logfs.org> <1371581225-27535-3-git-send-email-joern@logfs.org> In-Reply-To: <1371581225-27535-3-git-send-email-joern@logfs.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.135.74.216] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2136 Lines: 74 Hi Joern， On 2013/6/19 2:47, Joern Engel wrote: > It is counterintuitive at best that mmap'ing a hugetlbfs file with > MAP_HUGETLB fails, while mmap'ing it without will a) succeed and b) > return huge pages. > > Signed-off-by: Joern Engel > --- > mm/mmap.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 2a594246..76eb6df 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -33,6 +33,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1313,6 +1314,11 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, > return addr; > } > > +static inline int is_hugetlb_file(struct file *file) > +{ > + return file->f_inode->i_sb->s_magic == HUGETLBFS_MAGIC; > +} > + > SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, > unsigned long, prot, unsigned long, flags, > unsigned long, fd, unsigned long, pgoff) > @@ -1322,11 +1328,12 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, > > if (!(flags & MAP_ANONYMOUS)) { > audit_mmap_fd(fd, flags); > - if (unlikely(flags & MAP_HUGETLB)) > - return -EINVAL; > file = fget(fd); > if (!file) > goto out; > + retval = -EINVAL; > + if (unlikely(flags & MAP_HUGETLB && !is_hugetlb_file(file))) We already have is_file_hugepages(). Thanks, Jianguo Wu > + goto out_fput; > } else if (flags & MAP_HUGETLB) { > struct user_struct *user = NULL; > /* > @@ -1346,6 +1353,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, > flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); > > retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); > +out_fput: > if (file) > fput(file); > out: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/