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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 586D5ECDFB4 for ; Wed, 18 Jul 2018 03:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0FBC12075A for ; Wed, 18 Jul 2018 03:24:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=osandov-com.20150623.gappssmtp.com header.i=@osandov-com.20150623.gappssmtp.com header.b="Jp6AXexd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0FBC12075A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=osandov.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731664AbeGRD7t (ORCPT ); Tue, 17 Jul 2018 23:59:49 -0400 Received: from mail-pl0-f65.google.com ([209.85.160.65]:41371 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731578AbeGRD7t (ORCPT ); Tue, 17 Jul 2018 23:59:49 -0400 Received: by mail-pl0-f65.google.com with SMTP id w8-v6so1359093ply.8 for ; Tue, 17 Jul 2018 20:24:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=DOcETJK+mrW4NbvhRdPR+EyOGIwkzyC9IN9wH8Qu2Hw=; b=Jp6AXexdaMvlztcDHp83Ymgs7u6VjgklMsIwRDmjXf6mQNPOhNfc2hTqt5jJZiyWf1 uRt1zmZTHX8q42zA4P5Y25Ovj0ihoaAWEIW7xyH2DzsRD1aEgZpURSZUjkHK1pvEiliK bCqLXp+99Y7dfQ1WndBPgaXgz6athdwt7CJFAVwozA4dwdb8wD27NEgJWBA7SjXP6vEv DBy0yq27jbUBtZjYLyeReBNUY34kvroNS83RXStM/RUuCIlLb/MbXp2yZIc0sRFG3/LI 8jJRPhBFjNj+lyD3vlu6fugkNqHqfjX8DDL0G+rI9e1ETLz+W3yOOKxWZSogZWQCiiIM AsUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=DOcETJK+mrW4NbvhRdPR+EyOGIwkzyC9IN9wH8Qu2Hw=; b=I2BF2KNf2hHEpBMbqYBU39v37Mf5W68dRuKqHCtd+WqNPIAKj0I2vo4FgovE9vtn6V 4eMBtpWNAugMCJ3ivxbgHC8h0FwMCfKJ1VWM6QR70jNmNFtFxic5w8P3WYmWmlUSb+hH LVv1WkvQ2rncUXnvIgTDOF0l8tklq/3WRHOcu3xJiQCC6PnEib/E9vhXEXiWwDbfjpzT hlFChib33ZNp+dN3iyb49WzYFPddLcHZl2CTOoR44ZO0YyDMDsOXugBU6AV7JOnIdcLc srjTFNTnpH3jkP5ezMN35w2+ex6fkgFeGr1vIkWHSUWQLh1HTeYG8jcZuy1g05mNcV5V UbVw== X-Gm-Message-State: AOUpUlEkHuYAMJWMfFhRrngf0BWb/LdCM/DAFgEvaufnAKXBnoBp+Ejn 6SQ0vgUE7uZ9FxTB/OEobOiwaw== X-Google-Smtp-Source: AAOMgpcIT0gzIncCmwELJRMO560Sv30VfdOwv54kMW5PpQGaPSt/qLi5EOnDf4mh9HMRUilNLm2iRQ== X-Received: by 2002:a17:902:2006:: with SMTP id n6-v6mr4130645pla.325.1531884246713; Tue, 17 Jul 2018 20:24:06 -0700 (PDT) Received: from vader ([2620:10d:c090:180::1:bc4f]) by smtp.gmail.com with ESMTPSA id r87-v6sm9869934pfb.1.2018.07.17.20.24.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 17 Jul 2018 20:24:06 -0700 (PDT) Date: Tue, 17 Jul 2018 20:24:05 -0700 From: Omar Sandoval To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alexey Dobriyan , Eric Biederman , James Morse , Bhupesh Sharma , kernel-team@fb.com Subject: Re: [PATCH v2 2/7] proc/kcore: replace kclist_lock rwlock with rwsem Message-ID: <20180718032405.GB29351@vader> References: <783ba3becc424db45e5d5c93559fc40ef6173f01.1531440458.git.osandov@fb.com> <20180717193841.271d1c57b6f88d75c83892be@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180717193841.271d1c57b6f88d75c83892be@linux-foundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 17, 2018 at 07:38:41PM -0700, Andrew Morton wrote: > On Thu, 12 Jul 2018 17:09:34 -0700 Omar Sandoval wrote: > > > From: Omar Sandoval > > > > Now we only need kclist_lock from user context and at fs init time, and > > the following changes need to sleep while holding the kclist_lock. > > > > ... > > > > --- a/fs/proc/kcore.c > > +++ b/fs/proc/kcore.c > > @@ -59,8 +59,8 @@ struct memelfnote > > }; > > > > static LIST_HEAD(kclist_head); > > -static DEFINE_RWLOCK(kclist_lock); > > -static int kcore_need_update = 1; > > +static DECLARE_RWSEM(kclist_lock); > > +static atomic_t kcore_need_update = ATOMIC_INIT(1); > > It's unclear why kcore_need_update was changed to atomic_t - it's still > updated under kclist_lock? Not in the hotplug notifier (kcore_callback()) anymore, so I need the atomic_cmpxchg() in __kcore_update_ram(). That could use a mention in the commit message. > Maybe it's for a later patch. > >