From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "David Rientjes" <rientjes@google.com>
Cc: <linux-mm@kvack.org>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: [patch -mm] mm, doc: cleanup and clarify munmap behavior for hugetlb memory fix
Date: Fri, 03 Apr 2015 15:18:50 +0800 [thread overview]
Message-ID: <057b01d06dde$71738db0$545aa910$@alibaba-inc.com> (raw)
In-Reply-To: <057a01d06ddd$ff2550e0$fd6ff2a0$@alibaba-inc.com>
>
> Don't only specify munmap(2) behavior with respect the hugetlb memory, all
> other syscalls get naturally aligned to the native page size of the
> processor. Rather, pick out munmap(2) as a specific example.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> Documentation/vm/hugetlbpage.txt | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
> index 1270fb1..030977f 100644
> --- a/Documentation/vm/hugetlbpage.txt
> +++ b/Documentation/vm/hugetlbpage.txt
> @@ -313,8 +313,11 @@ into /proc/sys/vm/hugetlb_shm_group. It is possible for same or different
> applications to use any combination of mmaps and shm* calls, though the mount of
> filesystem will be required for using mmap calls without MAP_HUGETLB.
>
> -When using munmap(2) to unmap hugetlb memory, the length specified must be
> -hugepage aligned, otherwise it will fail with errno set to EINVAL.
> +Syscalls that operate on memory backed by hugetlb pages only have their lengths
> +aligned to the native page size of the processor; they will normally fail with
> +errno set to EINVAL or exclude hugetlb pages that extend beyond the length if
> +not hugepage aligned. For example, munmap(2) will fail if memory is backed by
> +a hugetlb page and the length is smaller than the hugepage size.
>
>
> Examples
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
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> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next parent reply other threads:[~2015-04-03 7:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <057a01d06ddd$ff2550e0$fd6ff2a0$@alibaba-inc.com>
2015-04-03 7:18 ` Hillf Danton [this message]
2015-03-26 23:23 [patch 1/2] mm, doc: cleanup and clarify munmap behavior for hugetlb memory David Rientjes
2015-03-30 1:35 ` 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
2015-04-04 9:34 ` Jonathan Corbet
2015-04-09 19:46 ` David Rientjes
2015-04-11 13:26 ` Jonathan Corbet
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