From: Michal Hocko <mhocko@suse.com>
To: zhong jiang <zhongjiang@huawei.com>
Cc: akpm@linux-foundation.org, anshuman.khandual@arm.com,
mst@redhat.com, linux-mm@kvack.org,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH] mm: redefine the MAP_SHARED_VALIDATE to other value
Date: Mon, 8 Jul 2019 11:20:45 +0200 [thread overview]
Message-ID: <20190708092045.GA20617@dhcp22.suse.cz> (raw)
In-Reply-To: <1562573141-11258-1-git-send-email-zhongjiang@huawei.com>
[Cc Dan]
On Mon 08-07-19 16:05:41, zhong jiang wrote:
> As the mman manual says, mmap should return fails when we assign
> the flags to MAP_SHARED | MAP_PRIVATE.
>
> But In fact, We run the code successfully and unexpected.
What is the code that you are running and what is the code version.
> It is because MAP_SHARED_VALIDATE is introduced and equal to
> MAP_SHARED | MAP_PRIVATE.
This was a deliberate decision IIRC. Have a look at 1c9725974074 ("mm:
introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap
flags").
> Signed-off-by: zhong jiang <zhongjiang@huawei.com>
> ---
> include/uapi/linux/mman.h | 2 +-
> tools/include/uapi/asm-generic/mman-common-tools.h | 2 +-
> tools/include/uapi/linux/mman.h | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h
> index fc1a64c..1d3098e 100644
> --- a/include/uapi/linux/mman.h
> +++ b/include/uapi/linux/mman.h
> @@ -14,7 +14,7 @@
>
> #define MAP_SHARED 0x01 /* Share changes */
> #define MAP_PRIVATE 0x02 /* Changes are private */
> -#define MAP_SHARED_VALIDATE 0x03 /* share + validate extension flags */
> +#define MAP_SHARED_VALIDATE 0x04 /* share + validate extension flags */
>
> /*
> * Huge page size encoding when MAP_HUGETLB is specified, and a huge page
> diff --git a/tools/include/uapi/asm-generic/mman-common-tools.h b/tools/include/uapi/asm-generic/mman-common-tools.h
> index af7d0d3..4fc44d2 100644
> --- a/tools/include/uapi/asm-generic/mman-common-tools.h
> +++ b/tools/include/uapi/asm-generic/mman-common-tools.h
> @@ -18,6 +18,6 @@
> #ifndef MAP_SHARED
> #define MAP_SHARED 0x01 /* Share changes */
> #define MAP_PRIVATE 0x02 /* Changes are private */
> -#define MAP_SHARED_VALIDATE 0x03 /* share + validate extension flags */
> +#define MAP_SHARED_VALIDATE 0x04 /* share + validate extension flags */
> #endif
> #endif // __ASM_GENERIC_MMAN_COMMON_TOOLS_ONLY_H
> diff --git a/tools/include/uapi/linux/mman.h b/tools/include/uapi/linux/mman.h
> index fc1a64c..1d3098e 100644
> --- a/tools/include/uapi/linux/mman.h
> +++ b/tools/include/uapi/linux/mman.h
> @@ -14,7 +14,7 @@
>
> #define MAP_SHARED 0x01 /* Share changes */
> #define MAP_PRIVATE 0x02 /* Changes are private */
> -#define MAP_SHARED_VALIDATE 0x03 /* share + validate extension flags */
> +#define MAP_SHARED_VALIDATE 0x04 /* share + validate extension flags */
>
> /*
> * Huge page size encoding when MAP_HUGETLB is specified, and a huge page
> --
> 1.7.12.4
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-07-08 9:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-08 8:05 zhong jiang
2019-07-08 9:20 ` Michal Hocko [this message]
2019-07-08 13:52 ` zhong jiang
2019-07-08 16:43 ` Michal Hocko
2019-07-09 1:52 ` zhong jiang
2019-07-08 14:43 ` Matthew Wilcox
2019-07-09 1:53 ` zhong jiang
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