From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F1EF3EC2E1; Thu, 2 Apr 2026 15:57:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775145466; cv=none; b=RGApCQRZhA8ZmLOon0gypcPVdnB4bcK+L8pltG6upQCi4YHftu+6WmAV4z/a3Wka1cjJ2Hf2DLk7KDv5KETZyGbmbA/xk9KnuogPlcttQpdsYEdWQZ9Nh4eaf38s1BxJ+DhjFIat1BXYWvdwuQEbdu7GLVMXkGKOo7pzHMrRcAU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775145466; c=relaxed/simple; bh=Q3isgEbinPNEQMQQYyM5HlICe6RXhN4FkLMXIpHyJiA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Dkg8K5bcyhM2wmS+R85skUKaHfUUIpJbSR3fFZPQnq5CLAqSkFKUvnqP9bKpwn8Dm8zR+3UQcokCR6AVIRDy+eu5Lh3GHKKguvM44EWizrw1G6Zxzjn6pw4Q3VHx0sljzMiyu10G7MSYjfvy3VXG2elBtpwLq+piMQi41eJwRtg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aC2bcxa5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aC2bcxa5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 170F9C19424; Thu, 2 Apr 2026 15:57:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775145466; bh=Q3isgEbinPNEQMQQYyM5HlICe6RXhN4FkLMXIpHyJiA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aC2bcxa5QiwLtC2G74omcGwVCNKpRnr1wSBOZh+XXEYCii/OaHhldSCH2PGINeL3/ o5h8jOcdc1PfTqFzUFSFx3QoMvVPiEIN+p0/QsWA2l0XfwlO/jEK5uwrXgr3XlMBln dXClDBM7KYuBtPoGCEv0q7tEu+lN9PZEDqFJPxWOXErS8sDhOn9bgKK+B6rFtjkC92 /v2U+JHI+iJpgBWtF299ZFhca/GL3IuYalnnmQxKU97+MzWXY3iSVPvc+8XkT8PDYS agzOWHDlriZ6w2d9GpKnUWG6rhwq6lf0ZDvBVXIJMXRi3tSm+r9hvmCYi6flRZGHQg XxIWSOdO1pcQA== From: SeongJae Park To: Andrew Morton Cc: Liew Rui Yan , SeongJae Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 3/3] mm/damon: add synchronous commit for commit_inputs Date: Thu, 2 Apr 2026 08:57:30 -0700 Message-ID: <20260402155733.77050-4-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260402155733.77050-1-sj@kernel.org> References: <20260402155733.77050-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Liew Rui Yan Problem ======= Writing invalid parameters to sysfs followed by 'commit_inputs=Y' fails silently (no error returned to shell), because the validation happens asynchronously in the kdamond. Solution ======== To fix this, the commit_inputs_store() callback now uses damon_call() to synchronously commit parameters in the kdamond thread's safe context. This ensures that validation errors are returned immediately to userspace, following the pattern used by DAMON_SYSFS. Changes ======= 1. Added commit_inputs_store() and commit_inputs_fn() to commit synchronously. 2. Removed handle_commit_inputs(). This change is motivated from another discussion [1]. [1] https://lore.kernel.org/20260318153731.97470-1-aethernet65535@gmail.com Signed-off-by: Liew Rui Yan Reviewed-by: SeongJae Park Signed-off-by: SeongJae Park --- Changes from v2 (https://lore.kernelorg/20260329075415.36775-1-aethernet65535@gmail.com) - Rebase to latest mm-new. Changes from v1: - Restore the KERNEL_PARAM_OPS_FL_NOARG flag to keep the compatibility. - Link to V1: https://lore.kernel.org/20260328084524.5451-1-aethernet65535@gmail.com Changes from RFC-v6 - Removed unnecessary assignment (repeat) in commit_inputs_store(). - Change the return value; if an error occurs, return the error code. - Removed the RFC tag. - Link to RFC-v6: https://lore.kernel.org/20260327062558.66392-1-aethernet65535@gmail.com Changes from RFC-v5: - Removed unnecessary assignment (data) in commit_inputs_store(). - Return -EINVAL instead of -EBUSY when 'commit_inputs' is triggered while kdamond is not running. - Link to RFC-v5: https://lore.kernel.org/20260325013939.18167-1-aethernet65535@gmail.com Changes from RFC-v4: - Rename the 'yes' variable in commit_inputs_store() to the more understandable 'commit_inputs_request'. - Return -EBUSY instead of -EINVAL when 'commit_inputs' is triggered while kdamond is not running. - Link to RFC-v4: https://lore.kernel.org/20260323021648.6590-1-aethernet65535@gmail.com Changes from RFC-v3: - Added checks for 'ctx' and 'damon_is_running()' to prevent NULL pointer dereference during early boot. (Found by Sashiko.dev) - Removed handle_commit_inputs() and its associated polling logic as they have become dead code after moving to the synchronous damon_call() approach. - Ensure the 'commit_inputs' is properly updated. Link to RFC-v3: https://lore.kernel.org/20260322231522.32700-1-aethernet65535@gmail.com Changes from RFC-v2: - Removed damon_validate_attrs(), now using damon_commit_ctx() for synchronous validation in the kdamond context. - Following DAMON_SYSFS pattern for synchronous commit via damon_call(). - Link to RFC-v2: https://lore.kernel.org/20260321140926.22163-1-aethernet65535@gmail.com Changes from RFC-v1: - Remove question from commit message area. - Added synchronous validation for DAMON_RECLAIM. - Rename damon_valid_attrs() -> damon_validate_attrs(). - Exported a new function damon_validate_attrs() and declared it in damon.h. - Link to RFC-v1: https://lore.kernel.org/20260321002642.22712-1-aethernet65535@gmail.com mm/damon/lru_sort.c | 46 ++++++++++++++++++++++++++++++++++++++------- mm/damon/reclaim.c | 46 ++++++++++++++++++++++++++++++++++++++------- 2 files changed, 78 insertions(+), 14 deletions(-) diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c index 554559d72976..641af42cc2d1 100644 --- a/mm/damon/lru_sort.c +++ b/mm/damon/lru_sort.c @@ -39,7 +39,6 @@ static bool enabled __read_mostly; * the re-reading, DAMON_LRU_SORT will be disabled. */ static bool commit_inputs __read_mostly; -module_param(commit_inputs, bool, 0600); /* * Desired active to [in]active memory ratio in bp (1/10,000). @@ -349,18 +348,51 @@ 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, + }; + + if (!val) { + commit_inputs_request = true; + } else { + err = kstrtobool(val, &commit_inputs_request); + if (err) + return err; + } - if (!commit_inputs) + if (!commit_inputs_request) return 0; - err = damon_lru_sort_apply_parameters(); - commit_inputs = false; - return err; + /* + * Skip damon_call() if ctx is not initialized to avoid + * NULL pointer dereference. + */ + if (!ctx) + return -EINVAL; + + err = damon_call(ctx, &control); + + return err ? err : control.return_code; } +static const struct kernel_param_ops commit_inputs_param_ops = { + .flags = KERNEL_PARAM_OPS_FL_NOARG, + .set = damon_lru_sort_commit_inputs_store, + .get = param_get_bool, +}; + +module_param_cb(commit_inputs, &commit_inputs_param_ops, &commit_inputs, 0600); + static int damon_lru_sort_damon_call_fn(void *arg) { struct damon_ctx *c = arg; @@ -374,7 +406,7 @@ static int damon_lru_sort_damon_call_fn(void *arg) damon_lru_sort_cold_stat = s->stat; } - return damon_lru_sort_handle_commit_inputs(); + return 0; } static struct damon_call_control call_control = { diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c index 86da14778658..4fc4a54b5e54 100644 --- a/mm/damon/reclaim.c +++ b/mm/damon/reclaim.c @@ -39,7 +39,6 @@ static bool enabled __read_mostly; * re-reading, DAMON_RECLAIM will be disabled. */ static bool commit_inputs __read_mostly; -module_param(commit_inputs, bool, 0600); /* * Time threshold for cold memory regions identification in microseconds. @@ -255,18 +254,51 @@ static int damon_reclaim_apply_parameters(void) return err; } -static int damon_reclaim_handle_commit_inputs(void) +static int damon_reclaim_commit_inputs_fn(void *arg) { + return damon_reclaim_apply_parameters(); +} + +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, + }; - if (!commit_inputs) + if (!val) { + commit_inputs_request = true; + } else { + err = kstrtobool(val, &commit_inputs_request); + if (err) + return err; + } + + if (!commit_inputs_request) return 0; - err = damon_reclaim_apply_parameters(); - commit_inputs = false; - return err; + /* + * Skip damon_call() if ctx is not initialized to avoid + * NULL pointer dereference. + */ + if (!ctx) + return -EINVAL; + + err = damon_call(ctx, &control); + + return err ? err : control.return_code; } +static const struct kernel_param_ops commit_inputs_param_ops = { + .flags = KERNEL_PARAM_OPS_FL_NOARG, + .set = damon_reclaim_commit_inputs_store, + .get = param_get_bool, +}; + +module_param_cb(commit_inputs, &commit_inputs_param_ops, &commit_inputs, 0600); + static int damon_reclaim_damon_call_fn(void *arg) { struct damon_ctx *c = arg; @@ -276,7 +308,7 @@ static int damon_reclaim_damon_call_fn(void *arg) damon_for_each_scheme(s, c) damon_reclaim_stat = s->stat; - return damon_reclaim_handle_commit_inputs(); + return 0; } static struct damon_call_control call_control = { -- 2.47.3