From 78049e94a171837e5a882814ca5bc4f14f265603 Mon Sep 17 00:00:00 2001 From: Jonghyeon Kim Date: Fri, 1 Apr 2022 11:28:57 -0700 Subject: mm/damon: prevent activated scheme from sleeping by deactivated schemes In the DAMON, the minimum wait time of the schemes decides whether the kernel wakes up 'kdamon_fn()'. But since the minimum wait time is initialized to zero, there are corner cases against the original objective. For example, if we have several schemes for one target, and if the wait time of the first scheme is zero, the minimum wait time will set zero, which means 'kdamond_fn()' should wake up to apply this scheme. However, in the following scheme, wait time can be set to non-zero. Thus, the mininum wait time will be set to non-zero, which can cause sleeping this interval for 'kdamon_fn()' due to one deactivated last scheme. This commit prevents making DAMON monitoring inactive state due to other deactivated schemes. Link: https://lkml.kernel.org/r/20220330105302.32114-1-tome01@ajou.ac.kr Signed-off-by: Jonghyeon Kim Reviewed-by: SeongJae Park Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/damon/core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/damon/core.c b/mm/damon/core.c index c1e0fed4e877..5ce8d7c867f0 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1019,12 +1019,15 @@ static int kdamond_wait_activation(struct damon_ctx *ctx) struct damos *s; unsigned long wait_time; unsigned long min_wait_time = 0; + bool init_wait_time = false; while (!kdamond_need_stop(ctx)) { damon_for_each_scheme(s, ctx) { wait_time = damos_wmark_wait_us(s); - if (!min_wait_time || wait_time < min_wait_time) + if (!init_wait_time || wait_time < min_wait_time) { + init_wait_time = true; min_wait_time = wait_time; + } } if (!min_wait_time) return 0; -- cgit v1.2.3-59-g8ed1b