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Howlett" , akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, sroettger@google.com, willy@infradead.org, gregkh@linuxfoundation.org, torvalds@linux-foundation.org, usama.anjum@collabora.com, corbet@lwn.net, merimus@google.com, rdunlap@infradead.org, jeffxu@google.com, jorgelo@chromium.org, groeck@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, dave.hansen@intel.com, linux-hardening@vger.kernel.org, deraadt@openbsd.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 177AD40005 X-Stat-Signature: ta5kwcoa6azwg75hyrx1q8388mcr87uw X-Rspam-User: X-HE-Tag: 1713549572-185907 X-HE-Meta: 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 j20q8IIP HsL7NhBWPKaPoUFGndjj6bkBUMgwrBTpt2v1yaV9bFVI9Fv1WyU3K7epz2fvOqM0szpsNpybDlyGAp+JSQTmeAx1H7HICJjNg304oFEJBIlbql30918voFNsnd2QmLbS7bHfZeG+LQ51+zAoPBzv6rykAZ4XFrhtQpQclkdlpHBIuW0n76ADo+TP6Hz43fDFQGyQTcipaAlH7oTuAI+FaFU+xjn47QYnrk2jCIGPjcTZY+4V+uEfM1gWQ43vfMOaz6ezU6fmwj4Y8dKVVYKWFVyW4xgSIHE6V+frXktLnRktvrKn2nC2J5NySxv4YUsmH43iFseIxdqrNirV+Jvzb4Qd4m5Hx525bhDQu29yB3+nd2pL1XB/t2NlSZGgwREUAu1goaAgNMzvS0IcZ0vEkpYgXbWVz8NUvt5IpM8JEl/hv+tncXbWU70betevPMhO9eZJU 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 Fri, Apr 19, 2024 at 2:22=E2=80=AFAM Jeff Xu wrote= : > The overhead is likely to grow linearly with the number of VMA, since > it takes time to retrieve VMA's metadata. > > Let's use one data sample to look at impact: > > Test: munmap 1000 memory range, each memory range has 1 VMA > > syscall__ vmas t t_mseal delta_ns per_vma % > munmap__ 1 909 944 35 35 104% > > For those 1000 munmap calls, sealing adds 35000 ns in total, or 35 ns per= call. Have you tried to spray around some likely() and unlikely()s? Does that make a difference? I'm thinking that sealing VMAs will be very rare, and mprotect/munmapping them is probably a programming error anyway, so the extra branches in the mprotect/munmap/madvice (etc) should be a nice target for some branch annotation. --=20 Pedro