From patchwork Sun Dec 12 08:28:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 523477 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A49FC433F5 for ; Sun, 12 Dec 2021 08:28:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229861AbhLLI2q (ORCPT ); Sun, 12 Dec 2021 03:28:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229739AbhLLI2p (ORCPT ); Sun, 12 Dec 2021 03:28:45 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40CA8C061714; Sun, 12 Dec 2021 00:28:45 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id BB9EFB80B60; Sun, 12 Dec 2021 08:28:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5263C341C6; Sun, 12 Dec 2021 08:28:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1639297722; bh=+vwEV3ZYpJcBSjbOoQrwfGcgCqTPvwgHQWlYU/fi9iY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z6ijJhFizilf6GF2g0lVgV57OFQBGnWLqDlLQLnhRfJBaqdjz4ebzllQS7PHG7CBr a+ItpL16EK5TP0oUmblYyCqq3/MVqYMSLcxFtbv58HX/B2Q40PK29uFH6waGSIdgFR Y8hC/Nqzc+BqwIZPi2AeiTLLIKiTj+S5P607XpXjYE0wxnERzra+vN5M9w7n+0lR6E g7CAE3a5JqSwva4165J6S4rIyMTnXkIxTws5wS25lrhpct1GGPRiqH7R3U87YNZ8x2 ZKiYtijq0VW9ULuU/xCl7AxBWR73Rxk5fMja0ZKAzI75XlDVsLn5up+y5s8PFHVHir z+Q5I8JX9gRXA== From: SeongJae Park To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, SeongJae Park , John Stultz , Thomas Gleixner , Linus Torvalds Subject: [PATCH for-v5.15.x 2/2] mm/damon/core: fix fake load reports due to uninterruptible sleeps Date: Sun, 12 Dec 2021 08:28:30 +0000 Message-Id: <20211212082831.26988-3-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211212082831.26988-1-sj@kernel.org> References: <20211212082831.26988-1-sj@kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 70e9274805fccfd175d0431a947bfd11ee7df40e upstream. Because DAMON sleeps in uninterruptible mode, /proc/loadavg reports fake load while DAMON is turned on, though it is doing nothing. This can confuse users[1]. To avoid the case, this commit makes DAMON sleeps in idle mode. [1] https://lore.kernel.org/all/11868371.O9o76ZdvQC@natalenko.name/ Link: https://lkml.kernel.org/r/20211126145015.15862-3-sj@kernel.org Fixes: 2224d8485492 ("mm: introduce Data Access MONitor (DAMON)") Reported-by: Oleksandr Natalenko Signed-off-by: SeongJae Park Tested-by: Oleksandr Natalenko Cc: John Stultz Cc: Thomas Gleixner Cc: # 5.15.x Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/damon/core.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 30e9211f494a..7a4912d6e65f 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -357,6 +357,15 @@ int damon_start(struct damon_ctx **ctxs, int nr_ctxs) return err; } +static void kdamond_usleep(unsigned long usecs) +{ + /* See Documentation/timers/timers-howto.rst for the thresholds */ + if (usecs > 20 * 1000) + schedule_timeout_idle(usecs_to_jiffies(usecs)); + else + usleep_idle_range(usecs, usecs + 1); +} + /* * __damon_stop() - Stops monitoring of given context. * @ctx: monitoring context @@ -370,8 +379,7 @@ static int __damon_stop(struct damon_ctx *ctx) ctx->kdamond_stop = true; mutex_unlock(&ctx->kdamond_lock); while (damon_kdamond_running(ctx)) - usleep_range(ctx->sample_interval, - ctx->sample_interval * 2); + kdamond_usleep(ctx->sample_interval); return 0; } mutex_unlock(&ctx->kdamond_lock); @@ -670,7 +678,7 @@ static int kdamond_fn(void *data) ctx->callback.after_sampling(ctx)) set_kdamond_stop(ctx); - usleep_range(ctx->sample_interval, ctx->sample_interval + 1); + kdamond_usleep(ctx->sample_interval); if (ctx->primitive.check_accesses) max_nr_accesses = ctx->primitive.check_accesses(ctx);