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Fri, 27 Mar 2026 00:14:13 -0700 (PDT) Received: from celestia ([2402:1980:898b:301c:d085:a35:99e7:ffec]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82c7d3c1374sm5208488b3a.44.2026.03.27.00.14.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Mar 2026 00:14:13 -0700 (PDT) From: Liew Rui Yan To: aethernet65535@gmail.com Cc: damon@lists.linux.dev, linux-mm@kvack.org, sj@kernel.org Subject: Re: (sashiko review) [RFC PATCH v6] mm/damon: add synchronous commit for commit_inputs Date: Fri, 27 Mar 2026 15:14:10 +0800 Message-ID: <20260327071410.73642-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260327070400.71707-1-aethernet65535@gmail.com> References: <20260327070400.71707-1-aethernet65535@gmail.com> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Forwarding Sashiko review for doing discussions via mails. > > # review url: https://sashiko.dev/#/patchset/20260327062558.66392-1-aethernet65535@gmail.com > # start of sashiko.dev inline review > commit 405545126e8bb145d7fb1fbb4f36016bc1f6c42c > Author: Liew Rui Yan > Date: Fri Mar 27 06:25:58 2026 +0000 > > mm/damon: add synchronous commit for commit_inputs > > This commit modifies the commit_inputs_store() callback to use damon_call() > for synchronously committing parameters in the kdamond thread's context. > This change aims to ensure validation errors are returned immediately to > userspace. > > Link: https://lore.kernel.org/20260318153731.97470-1-aethernet65535@gmail.com > > > diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c > > index 554559d72976..453033f3cb3e 100644 > > --- a/mm/damon/lru_sort.c > > +++ b/mm/damon/lru_sort.c > > [ ... ] > > > @@ -349,18 +348,47 @@ static int damon_lru_sort_apply_parameters(void) > > return err; > > } > > > > -static int damon_lru_sort_handle_commit_inputs(void) > > +static int damon_lru_sort_commit_inputs_fn(void *arg) > > +{ > > + return damon_lru_sort_apply_parameters(); > > +} > > + > > +static int damon_lru_sort_commit_inputs_store(const char *val, > > + const struct kernel_param *kp) > > +{ > > + bool commit_inputs_request; > > int err; > > + struct damon_call_control control = { > > + .fn = damon_lru_sort_commit_inputs_fn, > > + .repeat = false, > > + }; > > [ ... ] > > > + err = damon_call(ctx, &control); > > + > > + return control.return_code; > > } > > If damon_call() fails, for example returning -EINVAL when kdamond is not > running, err is set but the error code is never returned or checked. > > Will this cause the sysfs write to incorrectly succeed by returning the > default control.return_code of 0? > > Should it return err if err is non-zero, or control.return_code otherwise? Thank you for reminder. I will add 'return err ? err : control.return_code' back in next patch. > > diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c > > index 86da14778658..03e3300ce607 100644 > > --- a/mm/damon/reclaim.c > > +++ b/mm/damon/reclaim.c > > [ ... ] > > > +static int damon_reclaim_commit_inputs_store(const char *val, > > + const struct kernel_param *kp) > > +{ > > + bool commit_inputs_request; > > int err; > > + struct damon_call_control control = { > > + .fn = damon_reclaim_commit_inputs_fn, > > + .repeat = false, > > + }; > > [ ... ] > > > + err = damon_call(ctx, &control); > > + > > + return control.return_code; > > } > > Does this function have the same issue where the return value of > damon_call() is ignored? Yes, it have the same issue. Thank you for reminder. :> Best regards, Rui Yan