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b=ZJu28CUlO2hOmn+bHTdHQcqVxSlrGMAd4XKXqIG4p7S2zsN30kD757khd4oSNekN2 uI6IiF669T6xUMroAQckUtoeg1ohFrnvkENTNAAbuH0N5UXAhcfWOW0kREAK0hrd4h CzUZvaGI66MXqtiK5/LbP914J26SjRDUXgcpDAnSz7UUM3tJWx/B5uBTsN0f9UMJHc 5S5iEFMyYmKxb1o4JLa1k/fttfdZKUyw9bQ+189loLxyixkuwi1xhbp1fd4G9JnhWD idZ5yiWHlwlsxoHfT6yRdJl76evMIS6AQki3xYxC2yNdLWuJHlKfbKTKtjVMVRr6L2 DBZtIKm9U5dbA== 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 v2 3/4] mm/damon: add synchronous commit for commit_inputs Date: Sun, 26 Apr 2026 16:16:16 -0700 Message-ID: <20260426231619.107231-4-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260426231619.107231-1-sj@kernel.org> References: <20260426231619.107231-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 18C8BC0009 X-Rspamd-Server: rspam06 X-Stat-Signature: 6nfu6ob6t61oxwwggq93b7fa4sgfiy45 X-HE-Tag: 1777245390-285662 X-HE-Meta: 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 3KMvJ0nW jH/gV4JuC3dZnGrGz66ivNXSVIENedGeL5VEd9iUUsgo+NfG6Om73OWZIc9Lv3jY10gXbu7ANeIgr7xHJFhM+Bx6x8uoyWspZixwXsSEiCsf0/B9mNvJ0P2Wo186pXLN99xf8wpTiv/GtvGD4wIm2sy5jiCe1Gg1G3zfhkop0iCngw9ER5HCnaNuBpSnBUDpWgciqywC/W5CadzNtG2zwW0ENIw7FcclJyCQ6VFEUx3ZPdFQprPWNKxGKgQ7C+8cO3hwclFeXCSdkrQUjV82VGMgYyAD9OFYIJ48pU6gbzyPtFWw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 8494040b1ee48..7569e471160a0 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). @@ -340,18 +339,51 @@ 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; @@ -365,7 +397,7 @@ 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 fe7fce26cf6ce..b330ff1695907 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. @@ -246,18 +245,51 @@ 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; @@ -267,7 +299,7 @@ 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