From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B52B1CD343F for ; Mon, 18 May 2026 23:26:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E38C26B0005; Mon, 18 May 2026 19:26:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC2F56B0088; Mon, 18 May 2026 19:26:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C8A1A6B008C; Mon, 18 May 2026 19:26:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id AFCD66B0005 for ; Mon, 18 May 2026 19:26:16 -0400 (EDT) Received: from smtpin11.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 4894D140AB3 for ; Mon, 18 May 2026 23:26:16 +0000 (UTC) X-FDA: 84782126352.11.1AC81ED Received: from mail-yx1-f48.google.com (mail-yx1-f48.google.com [74.125.224.48]) by imf17.hostedemail.com (Postfix) with ESMTP id 6D2F540006 for ; Mon, 18 May 2026 23:26:14 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b="l2Z9wR/n"; spf=pass (imf17.hostedemail.com: domain of alexei.starovoitov@gmail.com designates 74.125.224.48 as permitted sender) smtp.mailfrom=alexei.starovoitov@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1779146774; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=eJpF8zNQx3fuLJ61e34VmvRInkcEmUUj8JXY5zhxM5M=; b=AcyVCrIbCtpwkv2QW/iIAhRV6q2xqwUkipuTtNq1UPVVTHMr35DrvsiNul+Yj6DAq2yZ3Y pHYXukWvjtSKjD+ienfFCBMf3DxB8aZ2CzXvgI3ZSlgTt0FkpkpNOacZk7DNQmiLFydvjx 4Pl903yjP/SjVIItYf+nYCN6EajQHLk= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b="l2Z9wR/n"; spf=pass (imf17.hostedemail.com: domain of alexei.starovoitov@gmail.com designates 74.125.224.48 as permitted sender) smtp.mailfrom=alexei.starovoitov@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779146774; a=rsa-sha256; cv=none; b=u1pX4RXT9r5KWaNXvkw9WJVWpm3u7NLV+9PQvvgJnzvxXWI/Iq66on16q2NUpeBk6Jz7uX lXK0GuFXegXPg63We16eF3N1uHQ+T8RIQuaDQ+KOup2afgsZj5wMRt0b4F9WQmJntN5a56 EHZLI32LT6Ym17jAPk1s2xymOylAC+0= Received: by mail-yx1-f48.google.com with SMTP id 956f58d0204a3-6579254f996so1881583d50.1 for ; Mon, 18 May 2026 16:26:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779146773; x=1779751573; darn=kvack.org; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-transfer-encoding:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=eJpF8zNQx3fuLJ61e34VmvRInkcEmUUj8JXY5zhxM5M=; b=l2Z9wR/nIQs+s+m8Gzp1rOUP3sfDt4d0M54TcGPNq0s20AMiRqMXE3gRUGF3NalQaM pjyuPlQr3I8/FV0/WCOIzLq4U+Z65eRXpwNRtBSUeOg2HulOotiUqJr+Vh8G5FoNPzsw ZwmsErE5A9ivAQ6QjN2ZGY/qsZC4X/KTsWwgAW6TOtZzUL2sm2sKye5BocCILPUgSVB+ P8qk08qq17E2DuqZAR0jOkrwPc+Y7eDP0ZCprLb/JQXcvPOxZEuLD3jfnfep9oqBz+cF FF0rfKpgEyeiqHGUsqV/AD6PjGmsS13PikVh/gNAiMLgQ0ewgmmm71lxChJTIwHg1WOG b+HA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779146773; x=1779751573; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-transfer-encoding:mime-version:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=eJpF8zNQx3fuLJ61e34VmvRInkcEmUUj8JXY5zhxM5M=; b=WvP5u1gr+IuIFGyvD8sXsssrzxQja1VKDa7q6GNC6KY0OllyvWwQPMeiBpuRFfj5va qKxDmDQJ1BU/fPZN7MwY7Fw17o8rI/OPlxe4lkw8n7Fmn+2Y0TsDJSjEb0VTbw/4FntH ThRcZXTbafjA5le9XhriyqZ/FK22+c668W3AiSff7YWqeLe7JQXfYVrhrZPP2hmD6w08 4dTrNSTfZdgADPnCbRzuy9nKAiXVVGo+qOApwvvC560IZcd87ca+HdAuxEa2W1jYegey X+WPACNadyWRTCNCiYo2/B/jLJiGuOcyzsHq1yxWz66aMHQDCSFOW+pjQbKScre2x+S6 jS2A== X-Forwarded-Encrypted: i=1; AFNElJ9kbFVccqoppCzVYJvRfL6GZJzQiGJxO4sFMGiY5tERuHWmDkIhm/yGA3owhVCpOcThKOz62+Yk1w==@kvack.org X-Gm-Message-State: AOJu0Yx93QFw7eCTBjGJoerw9PuhbYSRLeDu9uS03cyyq6nm3cSE7yPD yC9aASqFBYGaALaph9bmVelgBdb5Tgo+fn8WdCBbyTF/7GfJepAzkqeb X-Gm-Gg: Acq92OFmlg6zK5sIP16LTtW6lbKow9wczctuf/POsCmbbphHp7swIte2KvVml8NsRFi jQnqzs+8gNl8sn0tf4aQj53i/lJpPzUe/W33kQJPlTLw9TFnq1R1E80YmfcIEe431/Fg+ZN2p2o rxpkxrTMak9nGy6cbdvAoYpY6dYN7fX1i2C6AftFrbe+jgX00RL5aCzbok4TCFrJNBdg017/gjJ 16WGE8PlUbBKTRQuSkHournMZt91Mokc0T2Nyhp8CgAT6qSrlrK8sMDFd2Xfj3RwSz3pixYxE99 NjkfiHpOANtR+jzdVmq20zVoEdBt9BwuRyvVv09eExGUx4ZAUGhkxAXaxI63mpsFxOW0/CNoWiw XktAsik76G4nZZ1+tgSvUJZwq8wBOoT/RCoIltEYGlPBh6dabMZXc87pBnbXi+StcbaumKiF5yG V0VG3y+a9jaSZEVIZPh82qYgS2VNqwSvT5kTI/qrOIpDQ8K6J+amTF5IFDXX48iOQxWMzAIdW3c lzqkwVh+/QuUw8pmw== X-Received: by 2002:a05:690e:14c9:b0:65e:438e:c025 with SMTP id 956f58d0204a3-65e438edademr10259078d50.19.1779146773245; Mon, 18 May 2026 16:26:13 -0700 (PDT) Received: from localhost ([2a03:2880:f806:52::]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-65e0db0aa51sm7022713d50.12.2026.05.18.16.26.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 May 2026 16:26:12 -0700 (PDT) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 18 May 2026 16:26:11 -0700 Message-Id: Cc: "David Vernet" , "Andrea Righi" , "Changwoo Min" , "Alexei Starovoitov" , "Andrii Nakryiko" , "Daniel Borkmann" , "Martin KaFai Lau" , "Kumar Kartikeya Dwivedi" , "Catalin Marinas" , "Will Deacon" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Dave Hansen" , "Andrew Morton" , "David Hildenbrand" , "Mike Rapoport" , "Emil Tsalapatis" , , , , , , Subject: Re: [PATCH 7/8] sched_ext: Sub-allocator over kernel-claimed BPF arena pages From: "Alexei Starovoitov" To: "Tejun Heo" , "Peter Zijlstra" X-Mailer: aerc References: <20260517211232.1670594-1-tj@kernel.org> <20260517211232.1670594-8-tj@kernel.org> <20260518072042.GP3102624@noisy.programming.kicks-ass.net> In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6D2F540006 X-Stat-Signature: nftff49acfa4cgf5j9how3j9do6jwsw5 X-HE-Tag: 1779146774-1659 X-HE-Meta: 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 HxqJLKHN 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon May 18, 2026 at 12:51 PM PDT, Tejun Heo wrote: > Hello, > > On Mon, May 18, 2026 at 09:20:42AM +0200, Peter Zijlstra wrote: > ... >> Should this really be part of scx rather than be part of the bpf-arena >> thing proper? > > It's just a layer on top of arena. If bpf folks are okay with it, I don't > see why it can't be a common utility thing on the bpf side. Well, this gen_pool based allocator of arena memory is a temporary hack. It's ok for rare allocation like in this at scx init time, but not suitable for active arena management. We don't need to expose it beyond scx. Having said that the fast and generic allocator for arena is definitely nee= ded. This break through with scratch page and bpf_arena_handle_page_fault() cannot be overstated. It is a huge improvement for kernel <-> bpf interacti= on. Not only kfuncs can now read arena without ugly __get_kernel_nofault(), but we can reuse mm/slub.c to manage arena memory! The key idea is simply this: get_freepointer() { if (s->flags & SLAB_BPF_ARENA) return (void *)(s->arena_kern_vm_start | (u32)(unsigned long)ptr); } I'm sloping a prototype.