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 1AC1FE7717F for ; Mon, 16 Dec 2024 19:33:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A42DB6B00CD; Mon, 16 Dec 2024 14:33:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9F2096B00CE; Mon, 16 Dec 2024 14:33:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 893A56B00CF; Mon, 16 Dec 2024 14:33:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 690C06B00CD for ; Mon, 16 Dec 2024 14:33:02 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 17B70120940 for ; Mon, 16 Dec 2024 19:33:02 +0000 (UTC) X-FDA: 82901819910.29.70D999C Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by imf22.hostedemail.com (Postfix) with ESMTP id 0B2F4C000A for ; Mon, 16 Dec 2024 19:32:28 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=zx3Qn2jf; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf22.hostedemail.com: domain of surenb@google.com designates 209.85.160.169 as permitted sender) smtp.mailfrom=surenb@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1734377552; a=rsa-sha256; cv=none; b=d4/LLIi+6ME28VVJ3iNPp+ucJ41Dhlnc8qxLLI5XOryID6t+BwWqBCB0sJeZtG/D33LO6F B5syx1ysikCN1KVQV/Ux7NfDhSETlVgiB+Sp5ZOB6eLSxWqX1cOozXOnK+TcwVs+lL0HhB 6RT8LY43OnqoO7GlGCofcOBB3c1mLkY= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=zx3Qn2jf; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf22.hostedemail.com: domain of surenb@google.com designates 209.85.160.169 as permitted sender) smtp.mailfrom=surenb@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1734377552; 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=Rnp1pQwFAGvWyc7ujr4my+8rn/zofEngb5XuRNk7o1g=; b=fpy+b5foveWev9m5iJoxkA5V0GsU3kQv61tcHw8k8r7ENV2T+/RtQ5+dMeNE1KY+bFKIKm tXrGY3BWSWByfxflc/LH8AUrqGWOqi95sC9f01Ude5t86OwNJOqUMaUSWWF+Ko6toExu+v 8kunuKw86xBjpT9OpmfJ/F5MDesSQ/8= Received: by mail-qt1-f169.google.com with SMTP id d75a77b69052e-4678c9310afso33921cf.1 for ; Mon, 16 Dec 2024 11:32:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1734377579; x=1734982379; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=Rnp1pQwFAGvWyc7ujr4my+8rn/zofEngb5XuRNk7o1g=; b=zx3Qn2jfOkY8fyhuu64m5rLt2TrHmbdsthyBlaBBFyLTvZx1gwopffoKpJBljY2x71 qUd5Dj3QYVFAKskl26osnW3hZ4QJweOvqN5zYCsL7Tcgz3HeGsAT7BJDQzjvceoTae8/ uwgdKZZ+ysNjjZdkp/WXOvRlywtE1A44w3TudrrVOkbYsT9erJojfds5bC4SkgJU9mgH qTkWVCdpZVdvggAbk32kWqsZHmeRu7ap2PAY93g6LkkWPP7+aBMhQcxzn03sG/Wvamto vNokICAYYyqZnCp5/OvgbUDV6rfW2cQKqQdMlt1d3CqNcCpq+we9wmuKNiJe8r/G/mna NrlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1734377579; x=1734982379; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Rnp1pQwFAGvWyc7ujr4my+8rn/zofEngb5XuRNk7o1g=; b=CkvEUZnbfVQK+ykktS30puOv23kyZa6NDZHJC9VYn1pHtTULWfILGA/jk7QSCFl6Ke QpQajVrpPvxhixiQmZiEFPJedAuEZ4YLlQ/UP8fEZ86qvPccsReTIdkMeAGuFVmERnzp LlRSP7Gcm7UKh2vabV5zBFf7widwnKRXlV29BDJizZSEm4G5vgZTNtm2Pc7Sb4cluf6d sOXL9G0Wo/K1YlX9++lrkx67YA7PfiwprmbeJhYR5BJFjmj8bU5MQtzTVpMa/8of59FM 8y71WgyMBUIXnjmzKwroujePgvzIbR7ELrlRSfXt/wjGrFv+YqG2ghaoWxZHWCXzVgBz FIAg== X-Forwarded-Encrypted: i=1; AJvYcCXxeG9svPxqXjTHvw6HFg+Ig4c9+YItPfN1SjL/u9AHl3qogrkx3PUwTLzFUKrcDEHWKNdtMH0aCQ==@kvack.org X-Gm-Message-State: AOJu0YwFTqy3TOpq1Jm76LAYVGHL00hHld54y0m3zKkyjPp79yrazSFY bqXcvwNxnr5t07+JDRj/i2f5BwO7VLpTZwIPnKsQcBvTK8mI9m24hUtndBfQ3KgYFpwEr8ciSMs ObrGM0ua1gOxNdmCb5gYx070zD/NKS8m29lBi X-Gm-Gg: ASbGncvGubXzysVeUbFTSlgyBAhNzLV19pVOMtQPbkHFlZsIrZshAWUPhVMFJdP7gK4 VjL93jK7wyosBCCPs6ilSDuIMWccjN05NtnekEQ== X-Google-Smtp-Source: AGHT+IHj+HQHj2A2e+dxWaLP5rgIuLcnFIc+g+z1NFpaB1H8aqRrAsgQQMl3PJX8x8ome62Yd7ixIHA2lhsVnTFpE8Y= X-Received: by 2002:a05:622a:4ce:b0:466:8e4d:e981 with SMTP id d75a77b69052e-468f9944400mr137521cf.3.1734377578908; Mon, 16 Dec 2024 11:32:58 -0800 (PST) MIME-Version: 1.0 References: <20241211082541.GQ21636@noisy.programming.kicks-ass.net> <20241212091659.GU21636@noisy.programming.kicks-ass.net> <20241213095729.GC2484@noisy.programming.kicks-ass.net> <20241213183546.GB12338@noisy.programming.kicks-ass.net> In-Reply-To: From: Suren Baghdasaryan Date: Mon, 16 Dec 2024 11:32:47 -0800 Message-ID: Subject: Re: [PATCH 3/4] mm: replace rw_semaphore with atomic_t in vma_lock To: Peter Zijlstra Cc: Matthew Wilcox , akpm@linux-foundation.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: bpafmrshbni9e33p4u4ohmbpkq17k6a1 X-Rspam-User: X-Rspamd-Queue-Id: 0B2F4C000A X-Rspamd-Server: rspam08 X-HE-Tag: 1734377548-758006 X-HE-Meta: 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 kQG9ij/5 8qErCUiwYz2WSZ/bGUvEjx9NS01uwPkAwZW8z8arZtU+dAudPPz5kYI7G2VJBg8KcrXo8rQBGmdMF41n7Cayp+wApFmD3t5jM9ZKATsOq7AmWl5qhwd5mPRpwHseashfLtkmDqejR/mZs9YHmxNpDqSDNLe4wEowQdbhep7IBUrL1eXVsvDuNd3F5+uELgv7x1gIlbxFqpjFGjl1ElrV6HZEfn11OPp4OFLigf3EIYVqHoZyNsGQXaYrZFEkhSUV91/ynxQjv9nwCE+4VT2QutbXhvYaGBTW8Q6ok39N0Wo7I+bF1ZpTrBrfN8Dhv2BUl8qeqs83ahUdfkZzWSslmY4ewLceOXQnvyvcx X-Bogosity: Ham, tests=bogofilter, spamicity=0.309149, 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, Dec 13, 2024 at 10:37=E2=80=AFAM Suren Baghdasaryan wrote: > > On Fri, Dec 13, 2024 at 10:35=E2=80=AFAM Peter Zijlstra wrote: > > > > On Fri, Dec 13, 2024 at 09:45:33AM -0800, Suren Baghdasaryan wrote: > > > On Fri, Dec 13, 2024 at 1:57=E2=80=AFAM Peter Zijlstra wrote: > > > > > > > > On Thu, Dec 12, 2024 at 08:48:52PM -0800, Suren Baghdasaryan wrote: > > > > > > > > > I'm not sure if this is the best way to deal with this circular > > > > > dependency. Any other ideas? > > > > > > > > Move the waiting into an out-of-line slow-path? > > > > > > > > if (atomic_read(&vma->refcnt) !=3D 2) > > > > __vma_write_start_wait(mm, vma); > > > > > > The problem is not a function but the addition of struct rcuwait into > > > > Durr, in my brain that was a struct task_struct pointer, totally forgot > > we had a type there. Yeah, as Willy says, move it to compiler_types.h o= r > > somesuch. > > Got it. Thank you both! I posted the implementation of the mechanism we discussed here at: https://lore.kernel.org/all/20241216192419.2970941-11-surenb@google.com/ It ended up becoming a large patchset but most patches are very small logical units. Feedback is greatly appreciated!