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b=nn7Rv6ivC7Qq3N9Q2O4N+b11S4V40oQFQ1DMEUSOc/E3rrnbSK2u4VNh6NhBmDPbJ 10Ukb3Lr8fBfgKaWUKILYwqQM2xEtwj+SXDP67kxC8hzc3zbqD3/4VSn81ZZjJRLrZ Cg8UWDcIFvnQvHzeDr3NRAxkhCur9GAkwDSf+jvuKvuI23a0nQ6M+4PCJDags8pRss G2bG6mEdeZboujbyG+BAjbPvX/AlPm3V6ATtCQ0zhBLQ5lE/BJ6dT+D575csVvzD1w JL2pDlVCrXMyWoHhdoCJCvucgWP4w0Q6jIhN/vArJy/0JN4Qult420Z7OgKRbdNpk8 jUH2cCJd61QaA== From: SJ Park To: Andrew Morton Cc: SJ Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/4] mm/damon/core: set ctx->call_controls_obsolete in damon_new_ctx() Date: Wed, 2 Sep 2026 18:03:31 -0700 Message-ID: <20260903010334.93622-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260903010334.93622-1-sj@kernel.org> References: <20260903010334.93622-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 95F6116000E X-Stat-Signature: 5zur689cnfrcuxwze3msc7jten5snn9n X-HE-Tag: 1788397423-579260 X-HE-Meta: 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 bBSmRk61 L5U25vsbeUmwFCjROpBSPvEQIzg62Yd8S6WDQ8d4Qmpakf7v/faHauKbPB/0X8YQ/FjAZSozYTvjGlEhMXGardZ/zfPhTZ5dL4oeAZh9zICFQ1O6QTZwUNvk/QHtOqM1mN+w10luyMK5ycBdYC/PPKM+yirNsyHzxt0oLF0ZWOCs+Kx8Cgh3G96EAo8p7DJVjMmdpvyU4CyM8TMJhtQxyaKhlI5bHffbROlcHEQvbDplxhdypjtrhzDineanucLhEdLyVAZEwHijpfFu9iMWlNk7R/Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: damon_ctx->call_controls_obsolete is used to disallow damon_call() requests when the request cannot be served. The field is unset and set when the context execution is started and terminated, respectively. The intention is to allow damon_call() requests only while the context is actively being executed. damon_ctx constructor, damon_new_ctx() unsets the field, though. As a result, passing the damon_ctx parameter that never successfully damon_start()-ed to damon_call() can indefinitely hang. The callers should ensure to avoid the case. Such parameter validation is not always simple. Actually such bugs in DAMON_RECLAIM and DAMON_LRU_SORT have been found and fixed [1]. Set the field in damon_new_ctx(), so that DAMON API callers can pass the context parameter to damon_call() without the additional check. [1] https://lore.kernel.org/20260803134646.16640-1-sj@kernel.org Signed-off-by: SJ Park --- mm/damon/core.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 03407cf7f9646..56ec6f616fa9a 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -933,6 +933,7 @@ struct damon_ctx *damon_new_ctx(void) INIT_LIST_HEAD(&ctx->adaptive_targets); INIT_LIST_HEAD(&ctx->schemes); + ctx->call_controls_obsolete = true; prandom_seed_state(&ctx->rnd_state, get_random_u64()); return ctx; @@ -2196,10 +2197,6 @@ int damon_kdamond_pid(struct damon_ctx *ctx) * synchronization. The return value of the function will be saved in * &damon_call_control->return_code. * - * Note that this function should be called only after damon_start() with the - * @ctx has succeeded. Otherwise, this function could fall into an indefinite - * wait. - * * When this function is failed, the @ctx is guaranteed to be stopped. * * Return: 0 on success, negative error code otherwise. -- 2.47.3