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Mon, 05 Aug 2024 16:25:11 -0700 (PDT) Received: from localhost ([1.145.206.202]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2cfdeef43bcsm10813103a91.39.2024.08.05.16.24.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Aug 2024 16:25:11 -0700 (PDT) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 06 Aug 2024 09:24:56 +1000 Message-Id: Cc: "Michael Ellerman" , "Christophe Leroy" , "Pedro Falcato" , "kernel test robot" , "Jeff Xu" , , , , "Andrew Morton" , "Kees Cook" , "Liam R. Howlett" , "Dave Hansen" , "Greg Kroah-Hartman" , "Guenter Roeck" , "Jann Horn" , "Jonathan Corbet" , "Jorge Lucangeli Obes" , "Matthew Wilcox" , "Muhammad Usama Anjum" , =?utf-8?q?Stephen_R=C3=B6ttger?= , "Suren Baghdasaryan" , "Amer Al Shanawany" , "Javier Carrasco" , "Shuah Khan" , , , , , Subject: Re: [linus:master] [mseal] 8be7258aad: stress-ng.pagemove.page_remaps_per_sec -4.4% regression From: "Nicholas Piggin" To: "Linus Torvalds" , "Jeff Xu" X-Mailer: aerc 0.18.2 References: <202408041602.caa0372-oliver.sang@intel.com> In-Reply-To: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 60D1820006 X-Stat-Signature: 7zxsss9hzwjuqfb6zjbmh53dt16bjinr X-Rspam-User: X-HE-Tag: 1722900313-693716 X-HE-Meta: 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 7brSz72s 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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: List-Subscribe: List-Unsubscribe: On Tue Aug 6, 2024 at 5:48 AM AEST, Linus Torvalds wrote: > On Mon, 5 Aug 2024 at 12:38, Jeff Xu wrote: > > > > I'm curious, why does ppc need to unmap vdso ? ( other archs don't > > have unmap logic.) > > I have no idea. There are comments about 'perf' getting confused about > mmap counts when 'context.vdso' isn't set up. > > But x86 has the same context.vdso logic, and does *not* set the > pointer before installing the vma, for example. Also does not zero it > out on munmap(), although it does have the mremap logic. > > For all I know it may all be entirely unnecessary, and could be > removed entirely. I don't know much about vdso code, it predated my involvedment in ppc. Commit 83d3f0e90c6c8 says CRIU (checkpoint restore in userspace) is moving it around. Why CRIU wants to do that, I don't know. Can userspace on other archs not unmap their vdsos? Thanks, Nick