From patchwork Sun Dec 12 08:28:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 524233 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 A9A87C433EF for ; Sun, 12 Dec 2021 08:28:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229845AbhLLI2p (ORCPT ); Sun, 12 Dec 2021 03:28:45 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:57348 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229833AbhLLI2n (ORCPT ); Sun, 12 Dec 2021 03:28:43 -0500 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 D52B1B80B67; Sun, 12 Dec 2021 08:28:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE49EC341CB; Sun, 12 Dec 2021 08:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1639297720; bh=VRqGvqvUIyfK7wMSlQVPJTyXq7gEI7S+/DplM/pVHTU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=t3ifgksV6UkcAsmER6vXxC04jW+2nHoPZBtC0GJ/ESTGfAGNv8ieACbooVqvZc8qS t5tc+PXDOyhA+Cx2+QjiJTTVIoAYo6lDd5cwMfB70Df391yRYChaaUtZhZLFFixIBd TS202PrWoq4RIKAmiKv1I9ronL/XrtsUJxSE2cRSanz1i4R7FOVUkCbROV5y8QRxde 1ZcSjnQ1fGVE3y737Xd2WM7EDChCNEDCqFbSQloWbONjNGmOFJNLhthD7TP5xZgMZj BV6I2LwgiufYt3JvVGuQZB6qRlnHr3jIQuZ/zJ2W6kPmoQbxecIPIrF0jwnmuE5nTx 1iXl3eI+rHnlQ== 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 , Linus Torvalds Subject: [PATCH for-v5.15.x 1/2] timers: implement usleep_idle_range() Date: Sun, 12 Dec 2021 08:28:29 +0000 Message-Id: <20211212082831.26988-2-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 e4779015fd5d2fb8390c258268addff24d6077c7 upstream. Patch series "mm/damon: Fix fake /proc/loadavg reports", v3. This patchset fixes DAMON's fake load report issue. The first patch makes yet another variant of usleep_range() for this fix, and the second patch fixes the issue of DAMON by making it using the newly introduced function. This patch (of 2): Some kernel threads such as DAMON could need to repeatedly sleep in micro seconds level. Because usleep_range() sleeps in uninterruptible state, however, such threads would make /proc/loadavg reports fake load. To help such cases, this commit implements a variant of usleep_range() called usleep_idle_range(). It is same to usleep_range() but sets the state of the current task as TASK_IDLE while sleeping. Link: https://lkml.kernel.org/r/20211126145015.15862-1-sj@kernel.org Link: https://lkml.kernel.org/r/20211126145015.15862-2-sj@kernel.org Signed-off-by: SeongJae Park Suggested-by: Andrew Morton Reviewed-by: Thomas Gleixner Tested-by: Oleksandr Natalenko Cc: John Stultz Cc: # 5.15.x Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/delay.h | 14 +++++++++++++- kernel/time/timer.c | 16 +++++++++------- 2 files changed, 22 insertions(+), 8 deletions(-) diff --git a/include/linux/delay.h b/include/linux/delay.h index 1d0e2ce6b6d9..e8607992c68a 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -20,6 +20,7 @@ */ #include +#include extern unsigned long loops_per_jiffy; @@ -58,7 +59,18 @@ void calibrate_delay(void); void __attribute__((weak)) calibration_delay_done(void); void msleep(unsigned int msecs); unsigned long msleep_interruptible(unsigned int msecs); -void usleep_range(unsigned long min, unsigned long max); +void usleep_range_state(unsigned long min, unsigned long max, + unsigned int state); + +static inline void usleep_range(unsigned long min, unsigned long max) +{ + usleep_range_state(min, max, TASK_UNINTERRUPTIBLE); +} + +static inline void usleep_idle_range(unsigned long min, unsigned long max) +{ + usleep_range_state(min, max, TASK_IDLE); +} static inline void ssleep(unsigned int seconds) { diff --git a/kernel/time/timer.c b/kernel/time/timer.c index e3d2c23c413d..85f1021ad459 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -2054,26 +2054,28 @@ unsigned long msleep_interruptible(unsigned int msecs) EXPORT_SYMBOL(msleep_interruptible); /** - * usleep_range - Sleep for an approximate time - * @min: Minimum time in usecs to sleep - * @max: Maximum time in usecs to sleep + * usleep_range_state - Sleep for an approximate time in a given state + * @min: Minimum time in usecs to sleep + * @max: Maximum time in usecs to sleep + * @state: State of the current task that will be while sleeping * * In non-atomic context where the exact wakeup time is flexible, use - * usleep_range() instead of udelay(). The sleep improves responsiveness + * usleep_range_state() instead of udelay(). The sleep improves responsiveness * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces * power usage by allowing hrtimers to take advantage of an already- * scheduled interrupt instead of scheduling a new one just for this sleep. */ -void __sched usleep_range(unsigned long min, unsigned long max) +void __sched usleep_range_state(unsigned long min, unsigned long max, + unsigned int state) { ktime_t exp = ktime_add_us(ktime_get(), min); u64 delta = (u64)(max - min) * NSEC_PER_USEC; for (;;) { - __set_current_state(TASK_UNINTERRUPTIBLE); + __set_current_state(state); /* Do not return before the requested sleep time has elapsed */ if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS)) break; } } -EXPORT_SYMBOL(usleep_range); +EXPORT_SYMBOL(usleep_range_state); 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);