From: Hugh Dickins <hughd@google.com>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>, Jonathan Corbet <corbet@lwn.net>,
Davide Libenzi <davidel@xmailserver.org>,
Luiz Capitulino <lcapitulino@redhat.com>,
Shuah Khan <shuahkh@osg.samsung.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Joern Engel <joern@logfs.org>, Jianguo Wu <wujianguo@huawei.com>,
Eric B Munson <emunson@akamai.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-api@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [patch -mm] mm, doc: cleanup and clarify munmap behavior for hugetlb memory fix
Date: Thu, 2 Apr 2015 18:05:10 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.11.1504021802340.7876@eggly.anvils> (raw)
In-Reply-To: <alpine.DEB.2.10.1504021547330.15536@chino.kir.corp.google.com>
On Thu, 2 Apr 2015, David Rientjes wrote:
> Don't only specify munmap(2) behavior with respect the hugetlb memory, all
> other syscalls get naturally aligned to the native page size of the
> processor. Rather, pick out munmap(2) as a specific example.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
Thanks, yes, good wording: it is best to be a bit vague here,
since each msyscall takes the approach most convenient for it.
Acked-by: Hugh Dickins <hughd@google.com>
> ---
> Documentation/vm/hugetlbpage.txt | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
> index 1270fb1..030977f 100644
> --- a/Documentation/vm/hugetlbpage.txt
> +++ b/Documentation/vm/hugetlbpage.txt
> @@ -313,8 +313,11 @@ into /proc/sys/vm/hugetlb_shm_group. It is possible for same or different
> applications to use any combination of mmaps and shm* calls, though the mount of
> filesystem will be required for using mmap calls without MAP_HUGETLB.
>
> -When using munmap(2) to unmap hugetlb memory, the length specified must be
> -hugepage aligned, otherwise it will fail with errno set to EINVAL.
> +Syscalls that operate on memory backed by hugetlb pages only have their lengths
> +aligned to the native page size of the processor; they will normally fail with
> +errno set to EINVAL or exclude hugetlb pages that extend beyond the length if
> +not hugepage aligned. For example, munmap(2) will fail if memory is backed by
> +a hugetlb page and the length is smaller than the hugepage size.
>
>
> Examples
next prev parent reply other threads:[~2015-04-03 1:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-26 23:23 [patch 1/2] mm, doc: cleanup and clarify munmap behavior for hugetlb memory David Rientjes
2015-03-26 23:23 ` [patch 2/2] mm, selftests: test return value of munmap for MAP_HUGETLB memory David Rientjes
2015-03-26 23:52 ` Michael Ellerman
2015-03-27 13:58 ` [patch 1/2] mm, doc: cleanup and clarify munmap behavior for hugetlb memory Eric B Munson
2015-03-28 1:37 ` David Rientjes
2015-03-30 1:35 ` Hugh Dickins
2015-03-30 14:23 ` Eric B Munson
2015-03-30 20:23 ` Hugh Dickins
2015-04-02 22:40 ` David Rientjes
2015-04-02 22:50 ` [patch -mm] mm, doc: cleanup and clarify munmap behavior for hugetlb memory fix David Rientjes
2015-04-03 1:05 ` Hugh Dickins [this message]
2015-04-04 9:34 ` Jonathan Corbet
2015-04-09 19:46 ` David Rientjes
2015-04-11 13:26 ` Jonathan Corbet
[not found] <057a01d06ddd$ff2550e0$fd6ff2a0$@alibaba-inc.com>
2015-04-03 7:18 ` Hillf Danton
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