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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 797ADC43334 for ; Wed, 29 Jun 2022 02:36:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C2EEF6B0071; Tue, 28 Jun 2022 22:36:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BDF0B6B0072; Tue, 28 Jun 2022 22:36:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AA62F8E0001; Tue, 28 Jun 2022 22:36:01 -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 9954A6B0071 for ; Tue, 28 Jun 2022 22:36:01 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 665DD21137 for ; Wed, 29 Jun 2022 02:36:01 +0000 (UTC) X-FDA: 79629708522.02.56F5B8B Received: from gentwo.de (gentwo.de [161.97.139.209]) by imf01.hostedemail.com (Postfix) with ESMTP id A38BC4001A for ; Wed, 29 Jun 2022 02:36:00 +0000 (UTC) Received: by gentwo.de (Postfix, from userid 1001) id 62EECB00443; Wed, 29 Jun 2022 04:35:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.de; s=default; t=1656470158; bh=GIQsKenNZfcUeNZ7+iW3EIqnppyItHUTeM8wuuHIaV8=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=zH+NSQ0cLQCLe+mJTbezokxi6pn+fHgtTjFPSJNVXd7cV7TMVVpVTgaSngcN9qaYB 80/CdQ2xfpBo1tavkh81pjfi3eCXsm9l4HJ3KCsvkcw/Zr0O3sraLXilTwymH6p5Xc kgEW+1suqD4eDCpsACbkZpjWHsqD/9Eqt0qEFDvPXdWWJGQsSr60jiVcjZHbOsvdVy DsTIawCa16cn/0jrfSFKCXIxNrrcJdmiuOThqDbMboM3czumLMz6bJ+JfE2EyM+oL4 8of6ufxW172jrUFMiOR3YT7m/E5u0irlaV+Qcs/Iaq9UxpIP7aGt8xLhAR/EzRDhth otzyMctnLGCcQ== Received: from localhost (localhost [127.0.0.1]) by gentwo.de (Postfix) with ESMTP id 5FFC5B00068; Wed, 29 Jun 2022 04:35:58 +0200 (CEST) Date: Wed, 29 Jun 2022 04:35:58 +0200 (CEST) From: Christoph Lameter To: Alexei Starovoitov cc: Christoph Hellwig , David Miller , Daniel Borkmann , Andrii Nakryiko , Tejun Heo , Martin KaFai Lau , bpf , Kernel Team , linux-mm , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka Subject: Re: [PATCH bpf-next 0/5] bpf: BPF specific memory allocator. In-Reply-To: <20220628170343.ng46xfwi32vefiyp@MacBook-Pro-3.local> Message-ID: References: <20220628170343.ng46xfwi32vefiyp@MacBook-Pro-3.local> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656470161; a=rsa-sha256; cv=none; b=SPnib7mfCwyVL/YubuWnqR1YiGOsq2QteixzCJugQX/h323wbfq9c7g5F3bO+iJK9TVI88 MVjEqQ+oyH3e81wJmfqnrfF+24fQUujaW6KNXka/YAiLE8z+VJi425SAj7vhavMeGkp+Pw 6m9ADONKK/wyh8jTR8z5kOi1E/w8WN0= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=gentwo.de header.s=default header.b=zH+NSQ0c; spf=pass (imf01.hostedemail.com: domain of cl@gentwo.de designates 161.97.139.209 as permitted sender) smtp.mailfrom=cl@gentwo.de; dmarc=pass (policy=none) header.from=gentwo.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656470161; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=l3h7xUAfFnRZX2XxuoazGkAwJYwj3iR4aW9SbtGhsCU=; b=aRbAywb4ozPrCK7Dzk+1tXTeH9vzqX3BImvow7Ssk3aHTwZEKvK9oChlU4htTcO2Zq8/zF TTigLsE2E5ZD8ICvopadNRHDvs7aRvHcez8hRsmI/sLcfq9Fx1zHKkCFbbGDuo/x56r90d HEQndJBjsMHX1XmXMPjepcR4HDhZ/4k= X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A38BC4001A Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=gentwo.de header.s=default header.b=zH+NSQ0c; spf=pass (imf01.hostedemail.com: domain of cl@gentwo.de designates 161.97.139.209 as permitted sender) smtp.mailfrom=cl@gentwo.de; dmarc=pass (policy=none) header.from=gentwo.de X-Rspam-User: X-Stat-Signature: 31itjgd5mo35orow6hcp5kay3afxmin7 X-HE-Tag: 1656470160-110348 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: On Tue, 28 Jun 2022, Alexei Starovoitov wrote: > > That is a relatively new feature due to RT logic support. without RT this > > would be a simple irq disable. > > Not just RT. > It's a slow path: > if (IS_ENABLED(CONFIG_PREEMPT_RT) || > unlikely(!object || !slab || !node_match(slab, node))) { > local_unlock_irqrestore(&s->cpu_slab->lock,...); > and that's not the only lock in there. > new_slab->allocate_slab... alloc_pages grabbing more locks. Its not a lock for !RT. The fastpath is lockless if hardware allows that but then we go into more and more serialiation needs as the allocation gets more into the page allocator logic. > > allocation functions in the BPF logic like bpf_mem_alloc? How do you stop > > that from happening? > > here is the comment in the patch: > /* notrace is necessary here and in other functions to make sure > * bpf programs cannot attach to them and cause llist corruptions. > */ "notrace".... Ok Hmmm...