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AJvYcCVj73yWZgQwmUqiw4ks0SsRQ6cVAegmYlMwBPmDW8977LsSjKgtsNd6bPoDzC05wNltzsHFVlFhkuAfHjT5JY8bel0= X-Gm-Message-State: AOJu0YyjRRPdCTYnd9Iuen5RWPD0JkiDSMpqcnuNro8zsx4yek95595k 6s5r1NRb55KzmPU5ZsbbW255GqNxkCupTktpUKVJu3tmxEAzzl8nOTMUeeqmliX2+5cegAPB2zx zllIx/oCWo1rQBDxLZzU92dA5WHaCF3VMWKwJ X-Google-Smtp-Source: AGHT+IHDKybFd7xjBRooCMWNn/w6NoQhtyT6dyera+RHZ8++MzQjx2qRg4C4mrmTqvpJKMndQwKboNUTLGvAKAJR9gQ= X-Received: by 2002:a05:6512:b94:b0:52c:b243:cd02 with SMTP id 2adb3069b0e04-530d593c470mr35192e87.1.1722907410501; Mon, 05 Aug 2024 18:23:30 -0700 (PDT) MIME-Version: 1.0 References: <202408041602.caa0372-oliver.sang@intel.com> In-Reply-To: From: Jeff Xu Date: Mon, 5 Aug 2024 18:22:51 -0700 Message-ID: Subject: Re: [linus:master] [mseal] 8be7258aad: stress-ng.pagemove.page_remaps_per_sec -4.4% regression To: Linus Torvalds Cc: Nicholas Piggin , Michael Ellerman , Christophe Leroy , Pedro Falcato , kernel test robot , Jeff Xu , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, 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 , linux-api@vger.kernel.org, linux-mm@kvack.org, ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A9305140008 X-Stat-Signature: rs8z5gi53kmbd3scc6ean98bm5q68djs X-Rspam-User: X-HE-Tag: 1722907412-809047 X-HE-Meta: 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 tsmr+FZI Xv0EY2u12S1p32wyx/O15RCd8b6S/BpKq9AgGsmngEZylWf1VKvdp4VP73lq+k4ek2mLGdAqhJuy4F4E6JFJ9W0R6+12R0zo+FZqV+faPBe1ADSsIn9sMQ9Q43jGdrRb3b22eKUZ/67xrqPtgXHSime3LXf9kM0IgpnNYGZrAM0mPm1I3JDiHzMjWTeYLjIw6iipCJyPW5lpPq2+iqLub2Vm6FpqPezMcr/EX+uqh97heYiPMfVFtRjGGtthZQOxiF94GeBpuG52fll90Uea3J3iTl7dkofg+LiqWHotDyvUpghKmemUWjDY8ZQ1WieoHdZWhqAW1Bk0+nLa8VI3MlldfFtZ8DL4D4GsKz1nR1K4bk6vQFUeN6B/jsQ== 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 Mon, Aug 5, 2024 at 5:13=E2=80=AFPM Linus Torvalds wrote: > > On Mon, 5 Aug 2024 at 16:25, Nicholas Piggin wrote: > > > > Can userspace on other archs not unmap their vdsos? > > I think they can, and nobody cares. The "context.vdso" value stays at > some stale value, and anybody who tries to use it will just fail. > I want to seal the vdso :-), so I also care (not having it changeable from userspace) For the restore scenario, if vdso is sealed, I guess CRIU won't be able to relocate the vdso from userspace, I 'm interested in hearing vdso dev's input on this , e.g. is that possible to make CRIU compatible with memory sealing. > So what makes powerpc special is not "you can unmap the vdso", but > "powerpc cares". > > I just don't quite know _why_ powerpc cares. > > Judging by the comments and a quick 'grep', the reason may be > > arch/powerpc/perf/callchain_32.c > > which seems to have some vdso knowledge. > > But x86 does something kind of like that at signal frame generation > time, and doesn't care. > > I really think it's an issue of "if you screw with the vdso, you get > to keep both broken pieces". > > Linus