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[2003:e7:3722:c936:7ab7:4af7:b32c:2ca8]) by smtp.gmail.com with ESMTPSA id g10-20020a1709061c8a00b0092bd1a7f5fdsm10169ejh.57.2023.03.16.12.16.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Mar 2023 12:16:31 -0700 (PDT) Date: Thu, 16 Mar 2023 20:16:29 +0100 From: Nils Hartmann To: David Hildenbrand Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Using MAP_SHARE_VALIDATE in mmap without fd Message-ID: <20230316191629.2pet2mq5bpxl3z4p@archlinux> Reply-To: 20230310171617.wqnqs42l2viwjsz5@archlinux.kvack.org References: <20230310171617.wqnqs42l2viwjsz5@archlinux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3090B8002B X-Stat-Signature: 4cfj9yfshkara4yd76qfok8qfx6y96cg X-HE-Tag: 1678994192-961456 X-HE-Meta: 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 RVZBrhYT 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 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: On Thu, Mar 16, 2023 at 04:28:21PM +0100, David Hildenbrand wrote: > On 10.03.23 18:16, Nils Hartmann wrote: > > Hey, > > When used without a file pointer, EINVAL is returned. Is there a reason for this? > > You mean, using it with shared anonymous memory? (MAP_SHARED|MAP_ANON) > I assume you mean "file descriptor" not "file pointer". Yup thats what I meant. > The only reason MAP_SHARED_VALIDATE was introduced was due to MAP_SYNC, only > required for DAX. DAX does not apply to shared anonymous memory. Yeah I heard about it being introduced with MAP_SYNC. But since the manpage from mmap specifically says: 'MAP_SHARED_VALIDATE provides the same behaviour as MAP_SHARED', I didn't think it would make a difference > I guess nobody cared/cares. > Question is if we want to update the implementation (there has to be a good > reason IMHO) or simply update the man page, stating that MAP_SHARED_VALIDATE > is not supported for MAP_ANON. The only reason I can come up with, is naming consistency. But it's really a non-issue und updating the man page is definitly the saner option. > -- > Thanks, > > David / dhildenb > Best Regards, Nils