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 24184C48BF6 for ; Thu, 29 Feb 2024 04:17:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7ED386B009D; Wed, 28 Feb 2024 23:17:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 79DAF6B009E; Wed, 28 Feb 2024 23:17:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 665336B009F; Wed, 28 Feb 2024 23:17:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 56BA06B009D for ; Wed, 28 Feb 2024 23:17:49 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id EECE7A1A22 for ; Thu, 29 Feb 2024 04:17:48 +0000 (UTC) X-FDA: 81843533016.24.CCD3923 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) by imf02.hostedemail.com (Postfix) with ESMTP id 2EA5680004 for ; Thu, 29 Feb 2024 04:17:46 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=JQ8JifZn; spf=pass (imf02.hostedemail.com: domain of kent.overstreet@linux.dev designates 95.215.58.181 as permitted sender) smtp.mailfrom=kent.overstreet@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1709180267; 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=QA4CV5QoL6O9v4dQZqOYVzw93Y6Q2RCbxUs9bIOyLPU=; b=p+mXrN4DBRgbt/XCU6qUj3JkXeYMTADJtYgadbk+cv1GNKirgFJs0+r8HUPQeohnw3XFuT gQkqQw/7mGXRdtroz7TVXDGV66rXRV1YAcnP3T5wIzL8PlE7J1+KkPsqa2wAFME9Px7PDn N4d2ZIIaCFtzD0uD2HerUEw7rZJIco4= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709180267; a=rsa-sha256; cv=none; b=rQNPHrGBATza3oxxJBSY20GMttn7Gi6qnxxgouWkmrFvCKwc11uMDtCBZlFJ8b7EhHl2TU kMmGzIfueQGzA1Kpq65TJINYEYyYkmLkN8WkfHvPAcJIrZxJFzsm7rp2NX263Zq5as4vYL py9hnqGhpbXJZh/PHg33JihbWtmEubQ= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=JQ8JifZn; spf=pass (imf02.hostedemail.com: domain of kent.overstreet@linux.dev designates 95.215.58.181 as permitted sender) smtp.mailfrom=kent.overstreet@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Date: Wed, 28 Feb 2024 23:17:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1709180265; h=from:from: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; bh=QA4CV5QoL6O9v4dQZqOYVzw93Y6Q2RCbxUs9bIOyLPU=; b=JQ8JifZn9UJ5+zA311sYIq3hXQ7chHBT+DVKuDVIK0fmxKbOs6HRnAC9I2qhJ0TpVAckaZ Ha2BSUa2G71KfUeMPs+gmtau3SuCRHjTiKGPYs6QXDJEX0JcPt2qUjpk0F8bIRRaTlO3Pt L1h13oaQD9gCo8DiD9yH0oxWssO3ZKM= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kent Overstreet To: Matthew Wilcox Cc: Amir Goldstein , paulmck@kernel.org, lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, linux-fsdevel , Jan Kara Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Reclamation interactions with RCU Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Stat-Signature: bmqjo99x7sqkp6k6iz8aew1zjpwpa1sd X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2EA5680004 X-Rspam-User: X-HE-Tag: 1709180266-986636 X-HE-Meta: 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 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 Wed, Feb 28, 2024 at 07:37:58PM +0000, Matthew Wilcox wrote: > On Tue, Feb 27, 2024 at 09:19:47PM +0200, Amir Goldstein wrote: > > On Tue, Feb 27, 2024 at 8:56 PM Paul E. McKenney wrote: > > > > > > Hello! > > > > > > Recent discussions [1] suggest that greater mutual understanding between > > > memory reclaim on the one hand and RCU on the other might be in order. > > > > > > One possibility would be an open discussion. If it would help, I would > > > be happy to describe how RCU reacts and responds to heavy load, along with > > > some ways that RCU's reactions and responses could be enhanced if needed. > > > > > > > Adding fsdevel as this should probably be a cross track session. > > Perhaps broaden this slightly. On the THP Cabal call we just had a > conversation about the requirements on filesystems in the writeback > path. We currently tell filesystem authors that the entire writeback > path must avoid allocating memory in order to prevent deadlock (or use > GFP_MEMALLOC). Is this appropriate? It's a lot of work to assure that > writing pagecache back will not allocate memory in, eg, the network stack, > the device driver, and any other layers the write must traverse. Why would you not simply mark the writeback path with memalloc_nofs_save()?