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[195.135.220.15]) by mx.google.com with ESMTPS id g2si13607618edn.283.2019.07.08.02.20.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Jul 2019 02:20:59 -0700 (PDT) Received-SPF: pass (google.com: domain of mhocko@suse.com designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mhocko@suse.com designates 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B150DAE82; Mon, 8 Jul 2019 09:20:57 +0000 (UTC) Date: Mon, 8 Jul 2019 11:20:45 +0200 From: Michal Hocko To: zhong jiang Cc: akpm@linux-foundation.org, anshuman.khandual@arm.com, mst@redhat.com, linux-mm@kvack.org, Dan Williams Subject: Re: [PATCH] mm: redefine the MAP_SHARED_VALIDATE to other value Message-ID: <20190708092045.GA20617@dhcp22.suse.cz> References: <1562573141-11258-1-git-send-email-zhongjiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1562573141-11258-1-git-send-email-zhongjiang@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: [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 > --- > 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