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[47.72.151.34]) by smtp.gmail.com with ESMTPSA id j8sm5018838pfc.127.2022.01.20.17.08.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Jan 2022 17:08:18 -0800 (PST) From: Barry Song <21cnbao@gmail.com> To: khalid.aziz@oracle.com Cc: akpm@linux-foundation.org, arnd@arndb.de, dave.hansen@linux.intel.com, david@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, longpeng2@huawei.com, rppt@kernel.org, surenb@google.com, willy@infradead.org Subject: Re: [RFC PATCH 0/6] Add support for shared PTEs across processes Date: Fri, 21 Jan 2022 09:08:06 +0800 Message-Id: <20220121010806.5607-1-21cnbao@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-Rspamd-Queue-Id: 8B62DA000A X-Stat-Signature: gkqnz54wym1d9j4cy1dib5mqrraa17mn Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=X47hLxm9; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf15.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.210.177 as permitted sender) smtp.mailfrom=21cnbao@gmail.com X-Rspamd-Server: rspam08 X-HE-Tag: 1642727300-672965 Content-Transfer-Encoding: quoted-printable 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: > A file under /sys/fs/mshare can be opened and read from. A read from > this file returns two long values - (1) starting address, and (2) > size of the mshare'd region. >=20 > -- > int mshare_unlink(char *name) >=20 > A shared address range created by mshare() can be destroyed using > mshare_unlink() which removes the shared named object. Once all > processes have unmapped the shared object, the shared address range > references are de-allocated and destroyed. > mshare_unlink() returns 0 on success or -1 on error. I am still struggling with the user scenarios of these new APIs. This pat= ch supposes multiple processes will have same virtual address for the shared area? How can this be guaranteed while different processes can map differ= ent stack, heap, libraries, files? BTW, it seems you have different intention with the below? Shared page tables during fork[1] [1] https://lwn.net/Articles/861547/ Thanks Barry