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From: SeongJae Park <sj@kernel.org>
To: akpm@linux-foundation.org
Cc: john.stultz@linaro.org, tglx@linutronix.de, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, SeongJae Park <sj@kernel.org>,
	stable@vger.kernel.org
Subject: [PATCH v2 2/2] mm/damon/core: Fix fake load reports due to uninterruptible sleeps
Date: Thu, 25 Nov 2021 16:08:30 +0000	[thread overview]
Message-ID: <20211125160830.30153-3-sj@kernel.org> (raw)
In-Reply-To: <20211125160830.30153-1-sj@kernel.org>

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/

Fixes: 2224d8485492 ("mm: introduce Data Access MONitor (DAMON)")
Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.15.x
---
 mm/damon/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index daacd9536c7c..8cd8fddc931e 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -979,9 +979,9 @@ static unsigned long damos_wmark_wait_us(struct damos *scheme)
 static void kdamond_usleep(unsigned long usecs)
 {
 	if (usecs > 100 * 1000)
-		schedule_timeout_interruptible(usecs_to_jiffies(usecs));
+		schedule_timeout_idle(usecs_to_jiffies(usecs));
 	else
-		usleep_range(usecs, usecs + 1);
+		usleep_idle_range(usecs, usecs + 1);
 }
 
 /* Returns negative error code if it's not activated but should return */
@@ -1036,7 +1036,7 @@ static int kdamond_fn(void *data)
 				ctx->callback.after_sampling(ctx))
 			done = true;
 
-		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);
-- 
2.17.1


  parent reply	other threads:[~2021-11-25 16:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-25 16:08 [PATCH v2 0/2] mm/damon: Fix fake /proc/loadavg reports SeongJae Park
2021-11-25 16:08 ` [PATCH v2 1/2] timers: Implement usleep_idle_range() SeongJae Park
2021-11-25 16:08 ` SeongJae Park [this message]
2021-11-26 14:37 ` [PATCH v2 0/2] mm/damon: Fix fake /proc/loadavg reports Oleksandr Natalenko
2021-11-26 14:41   ` SeongJae Park

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