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AJvYcCWMTdsHsHeOg7rNtgO01S/o8f7Qs6icu9/mLrGuRs/9+PS4ehlfBxN+RU8VF+G79oZCPTJ7nM7/Hg==@kvack.org X-Gm-Message-State: AOJu0YyiToFiQVKFdw+VwNojqI9Tw47nGh7/GhLUbQ9E5roz9AvoIoLW SRIq/ht43dWzLCw23ZpnagtjCk2Hb1IIobA+7qq4CzoZ17T3H3Zot7plFbg/rp5SPf+LIyhLU/Z IBm3vq0i7K5wmCpw8FDooFVQMqaJIa3s= X-Gm-Gg: ASbGncvW3VdvS7gIyPYJW0CyEIywcAA3TWQBKMZOgnihLuxMsgARi3sWuXKTBW2axPG jSv/Oi7JXZUyGIamg1x790d9UO281D+ZQHcIG6z+RhYFKdCxiY4cbyJwTtMjbzgmJaZW479XNwx n6OXE9xmQSE63CmMkMIG5yCB3nzFfix9iP1NvqqbjzWQtzL9xOUsfrM7aPW3mUJIU+Qj+QUDX5f ZCjLCbVeZZezCudzfVRdrs17CZ2/OKzz0L/7+l2wdpkoANboEzCCmlaRAVtAydIdKOAnoDVR//y sIbKSOGTGcb4aB2Bn6cQOG1Qdw== X-Google-Smtp-Source: AGHT+IE3f6+lERRTkhgYiXq3WxT75J4vw1ZgvUH3e0qfRSUXuaIevkmchnqMJ7PQ613xIwPYrVjTKig6hmvR9YqtDco= X-Received: by 2002:a05:6402:40ce:b0:640:9bb0:a059 with SMTP id 4fb4d7f45d1cf-6491809850dmr4243505a12.10.1765099306875; Sun, 07 Dec 2025 01:21:46 -0800 (PST) MIME-Version: 1.0 References: <20251206131955.780557-1-mjguzik@gmail.com> <20251206131955.780557-3-mjguzik@gmail.com> In-Reply-To: From: Mateusz Guzik Date: Sun, 7 Dec 2025 10:21:35 +0100 X-Gm-Features: AQt7F2qIgG7x1XRP_ygSDiP1LRfgTA-lBEZIDe8d-fhDcgS3auCKA34L-aS3_r4 Message-ID: Subject: Re: [PATCH v3 2/2] pid: only take pidmap_lock once on alloc To: Matthew Wilcox Cc: oleg@redhat.com, brauner@kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 4ghejrcz5bztrrbpyx6rmrkyrbniqtg6 X-Rspam-User: X-Rspamd-Queue-Id: CD6FD180002 X-Rspamd-Server: rspam01 X-HE-Tag: 1765099308-200580 X-HE-Meta: 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 5SoQ/KZZ gMwHdapyCX1qA5HIga3CILz/mCO6fpTaDraImcX4vim4HxKPekk7zR+fh5rYY3iI128mEXVg8Hnqg4NMRTQ8xjJ0MrOgFHvkyDjkoLQXXTiNSFrExLg8vLtPm4ogY4P5JVWTB8w/e4hNvmjaXw3uyh09zzIbJonC3jW2xbeM1AnWrNcPMhfXDrXqtktMLUmvlesGaJs4xcpekCf2LW2itTK80w7+/tvoQIensKa29K645o6oNHTolJn+X1XxqQNgmpK1/tbWdFZ31B6r+Kg3Wtd3wGKs8PM7bgUD9Au83t1Xom4p+W2EHXuPgKFMz+XxGXOx38PnpXbaaMQcKBfKS8idHicBYUYVRPm2AUfuRCdY924fpoDj9Vyx2WkycXuNJw3GV9rTwrP/HJyLTRymT77zU/2iRS9UpkQBxPaXbyPMb0QnufghqBGsej1i/7HgGttXiRe16SbOjjYc= 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 Sun, Dec 7, 2025 at 8:21=E2=80=AFAM Matthew Wilcox = wrote: > > On Sat, Dec 06, 2025 at 02:19:55PM +0100, Mateusz Guzik wrote: > > - if (!pid) > > + if (unlikely(!pid)) > > Does this change anything? I was under the impression that gcc already > treats !p as unlikely. I don't know if gcc is guaranteed to act like that, most of my experience is with clang which was rather inconsistent about it.