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b=TDd9S5OuJ+XrVdbfEldX/D5gVlsDPXciDaB1qqqwyNrhejtaEG/W63bYL7YREGfc6 x9EdpA1Z5El9Ry9v58C9/tUiM2LYjGAHcHCGzf11Z7CPel/bNsFSZV/GtftxE6gJ0p dtanvwnVTu82ChFGI0CpFcq+LOdntane5xR+FPSXAMTOJgu5ZVtOtpT5ZNqHo0nrHK wV999tiuK0kEtoJFAxoByRTmVCWi2Gae/fjqQw3BYDTx5XeDsW/F+jgLSU0tWxRfb1 lcwufXWgJ7wvW18xAlOVsh9S70s5JMDIHehLEZAMNW2iYljQEXNh3dRq76MhcZw5x5 bV1ywA0yA8yfw== From: SeongJae Park To: SeongJae Park Cc: "# 5 . 16 . x" , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: (sashiko review) [RFC PATCH] mm/damon/core: use time_in_range() for damos quota window start Date: Sat, 28 Mar 2026 10:00:08 -0700 Message-ID: <20260328170008.48144-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260328163930.47096-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 8844E180012 X-Stat-Signature: tt4rhxhmagqnn7gj34krgp9hho59sfha X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1774717211-78408 X-HE-Meta: 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 q6ODtGnP x3uaroH1HrimKOpdomCgMQ9WwM8duccLXjzDcUzwM0onIh5amnT7DgCawohd6qszat6TH8qw2aKDJOQlk25tCU8AVtsfAY3xjBI99S3B1ZIB20loO5ndZNY41ZbYPBgH+evLSrgNxVdpu7rngPvllCYv4z5LmLoldjoapMjTZtkCXpTe9FZIX7PzF84cswIaQ0IFeqOlO6Jbze7danMoI49UYllwnFHl/j/3oDKX6WWw7352+lQixbXLfp2FOyyPo6dz+3/UaBHnUDjLOvxJZ/cGceqpw9d1Ev05msMyZqksSA7FVYFamWA8ZUX+ruNo4gvplgH0X0tuJcgDu5+GbA5YW9qaI3DU9gC7C9dOapuumS/I= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Forwarding Sashiko review for doing discussions via mails. # review url: https://sashiko.dev/#/patchset/20260328163930.47096-1-sj@kernel.org # start of sashiko.dev inline review commit 2ee07f5a4fcf25b39aeac61c6b88fe3fdfd0c9b6 Author: SeongJae Park mm/damon/core: use time_in_range() for damos quota window start This commit attempts to fix a stall in DAMOS quota charge windows when a scheme is deactivated for more than LONG_MAX jiffies. It replaces time_after_eq() with !time_in_range() to properly handle the extended time wrap-around. Link: https://lore.kernel.org/20260324040722.57944-1-sj@kernel.org > diff --git a/mm/damon/core.c b/mm/damon/core.c > index db6c67e52d2b..8e47183473d3 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -2452,7 +2452,7 @@ static void damos_adjust_quota(struct damon_ctx *c, struct damos *s) > } > > /* New charge window starts */ > - if (time_after_eq(jiffies, quota->charged_from + > + if (!time_in_range(jiffies, quota->charged_from, quota->charged_from + > msecs_to_jiffies(quota->reset_interval))) { Does this introduce an off-by-one regression that extends every quota charge window by 1 jiffy? time_in_range(a, b, c) evaluates the inclusive interval [b, c], which means it returns true when jiffies exactly equals the end of the interval. The original code used time_after_eq(), which correctly triggered the new charge window exactly on that jiffy. By replacing it with !time_in_range(), the reset evaluates to false on that exact jiffy and is delayed until the next jiffy. For small reset_interval configurations or low CONFIG_HZ values, this 1-jiffy delay might alter the effective quota replenishment rate. Would using !time_in_range_open() preserve the exact original timing semantics while still fixing the wrap-around stall issue? > if (damos_quota_is_set(quota) && > quota->charged_sz >= quota->esz) # end of sashiko.dev inline review # review url: https://sashiko.dev/#/patchset/20260328163930.47096-1-sj@kernel.org # # hkml [1] generated a draft of this mail. It can be regenerated # using below command: # # hkml patch sashiko_dev --for_forwarding \ # 20260328163930.47096-1-sj@kernel.org # # [1] https://github.com/sjp38/hackermail Sent using hkml (https://github.com/sjp38/hackermail)