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 BB8E6C433EF for ; Fri, 15 Jul 2022 17:07:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1A1B1940205; Fri, 15 Jul 2022 13:07:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 151859401FB; Fri, 15 Jul 2022 13:07:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 018AA940205; Fri, 15 Jul 2022 13:07:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id E3DCB9401FB for ; Fri, 15 Jul 2022 13:07:42 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 9945D814A9 for ; Fri, 15 Jul 2022 17:07:42 +0000 (UTC) X-FDA: 79689965964.17.1F60DE1 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf23.hostedemail.com (Postfix) with ESMTP id 1F39314009C for ; Fri, 15 Jul 2022 17:07:41 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3D1036226A; Fri, 15 Jul 2022 17:07:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E1AEC34115; Fri, 15 Jul 2022 17:07:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657904860; bh=aggAZRjimU1oJPtRHtLMPAK6iTKXIlW41DBUfmAz8qI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U19kf46l/YYlZcR9ZNwU59Pd+entD/+0E42IdwLJFyTvElEzF8tmSew0f/9PSprgT WeFOpO4fsrwt20+WWwEtNDGz9yLdg28CBv1BTPKrPhw9RJJn1MAdYd4quRbCadhuhJ qnrNzyp2dJbYeSX24E/VaPy+MIjINjRjWHqa6X3fCh3Hm/inmQueUiF4375kuWbPNF 86Orwu7OjmZILw3eS+JHKH9Mi9io5viMs3LIOfIzM8RHMQrFwqcT1PE5+D9jFmgann 5hpz3JW6h30aP5xnm4d0OE4P7qfm2uOXci+V9gF2nxi11cp5+xUpAfSrutjX4g1x0Y q961dkZXCvNJA== From: SeongJae Park To: Yuanzheng Song Cc: sj@kernel.org, akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/damon/reclaim: fix 'enabled' is incorrectly set because 'system_wq' is not initialized Date: Fri, 15 Jul 2022 17:07:36 +0000 Message-Id: <20220715170736.126498-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220715061609.48463-1-songyuanzheng@huawei.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657904862; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=UeQBnvIfGNsikk3rPfn84H5WcczEp62KZnYzvhrISeM=; b=acInrTuUE50bTZ7hIPnHFJV5HSd00EI3W3fovCfXYMinW7JJFVhHPPRY+UoZTzK8KRr96v KrTvpsliU4bpuXn0q6dQrSI/Snblru0xRa6S+1/N+daYax6V51J9BkYx67Tt5Z3dKHTfe1 3wgNZAbCB6K2Ezy4GihSRgmbisd4G6E= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657904862; a=rsa-sha256; cv=none; b=4eTCMAFGIN6mvgFJ7oTQiRU/89UGbl2HMCWG7zu+z2C87LeGkAUY+onFzai/z/xpFmIVAj mHYlgsiZ0oVFRJo0Xh1Bx0m0njt8Sdk/MeJP2yX2bF0/807VntrDo7e4zwC6WTrYoHUWQM Lf4AuRxOZuCjvab9S3H2VVPpkIJKnLM= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=U19kf46l; spf=pass (imf23.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=U19kf46l; spf=pass (imf23.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspamd-Queue-Id: 1F39314009C X-Stat-Signature: 5muas8hua78bt8wcgm1g67srpq84g184 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1657904861-952845 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: Hello Yuanzheng, On Fri, 15 Jul 2022 06:16:09 +0000 Yuanzheng Song wrote: > The 'enabled' will be incorrectly set because the 'system_wq' > might not initialized yet. This results in 'enabled=true', > but the 'damon_reclaim_timer' is inactive. So fix it by moving > the judgment logic of the 'damon_reclaim_initialized' to the > start position of the enable_store(). Thank you for this patch! In the case, however, 'damon_reclaim_init()' will activate 'damon_reclaim_timer', which will check the 'enabled' and start DAMON later. So 'enabled' will inconsistently set while DAMON_RECLAIM is not really enabled for a moment, but those will eventually be consistent. This patch could reduce the duration of the inconsistent state. However, this would break boot-time DAMON_RECLAIM enabling, which adds 'damon_reclaim.enabled=true' to the kernel parameter, as this change will set 'enabled' as 'false' in the early 'damon_reclaim_enabled_store()', so that the later 'damon_reclaim_initialized()' activated 'damon_reclaim_timer' shows 'enabled' as 'false' and therefore doesn't start DAMON. If there is anything I'm missing, please let me know. Thanks, SJ > > Fixes: 294928293813 ("mm/damon/reclaim: schedule 'damon_reclaim_timer' only after 'system_wq' is initialized") > Signed-off-by: Yuanzheng Song > --- > mm/damon/reclaim.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c > index e69b807fefe4..b13d5a02bf2e 100644 > --- a/mm/damon/reclaim.c > +++ b/mm/damon/reclaim.c > @@ -374,13 +374,14 @@ static bool damon_reclaim_initialized; > static int damon_reclaim_enabled_store(const char *val, > const struct kernel_param *kp) > { > - int rc = param_set_bool(val, kp); > - > - if (rc < 0) > - return rc; > + int rc; > > /* system_wq might not initialized yet */ > if (!damon_reclaim_initialized) > + return -EINVAL; > + > + rc = param_set_bool(val, kp); > + if (rc < 0) > return rc; > > schedule_delayed_work(&damon_reclaim_timer, 0); > -- > 2.25.1