From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 42604C61DB9 for ; Thu, 27 Aug 2026 04:29:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 176E56B008C; Thu, 27 Aug 2026 00:29:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0DA886B0096; Thu, 27 Aug 2026 00:29:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D35076B0092; Thu, 27 Aug 2026 00:29:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id ACB426B008C for ; Thu, 27 Aug 2026 00:29:32 -0400 (EDT) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 1D480C02F3 for ; Thu, 27 Aug 2026 04:29:32 +0000 (UTC) X-FDA: 85145770584.26.36CB7C6 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf07.hostedemail.com (Postfix) with ESMTP id 8BB1940005 for ; Thu, 27 Aug 2026 04:29:30 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=izYrMHPw; spf=pass (imf07.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787804970; b=W1NPDky8J9DBVaT0VTmz9s4IoCFw3cB/rJthySiadK55YYlohc12CbJFqTZtv4K2L1TgI/ 5M0w4egp3uzVyfBO5rw4gpR3DpuToUMi6s7xGg+aLjUp+wjXphWIfZR6pple12+tI8FxPn 0LlQIaWHLReYENN3wfVmw89gKraivJI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787804970; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nERbAFEHHSw5ax7MRWud0rpkMohS2ci96UJ8OD+KyJc=; b=N6oY3YgxYayHP0X3vnt+zVmRCuS03H+7PZ5VjZMS76E39674Mm+2iLr1EW80M0pfNvfHry y/v2Tj/oWOfgs5EHtINAXsTmzO1WMf+9XCubN9/l4uXsmEotXJ5dsyaHzHmB0BjHDymIqF sixVNxxfam+YxvQLXJRjnTon5904PD4= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=izYrMHPw; spf=pass (imf07.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 1AEA1600DB; Thu, 27 Aug 2026 04:29:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FF341F00A3E; Thu, 27 Aug 2026 04:29:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787804969; bh=nERbAFEHHSw5ax7MRWud0rpkMohS2ci96UJ8OD+KyJc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=izYrMHPwxZ/T5mohTVMD2kb/EMqa5Sw1xgHZkTwTlhGJXkBmsvABfHygDlg84j6ry RueknLBCEZsnFp53JM/LEDbEMLrOb6zFh2FHV64Qer50CtGPcbnjnPAzGRuqKBPBu4 0fij/rL9wBRUJOzRG5fDySXAvMbil4F1h/J1oo5taORYj0Vqb2OrZY1Axz5UiKcCMK 0dLPK/8O3Xia6oTGIISTWtU7e7aXGERZuNtsa9AzZwtciEBXNy6Ntb+fA0g7cjR1OO 3svM2t9PAz+hdYacgQaho2YIQT1+SRnsdveN2DRY5Rk8nGMcXdTbOP45kA+Ow0VsOd EMBggIeJ1YlwQ== From: SJ Park To: Cc: SJ Park , stable@vger.kernel.org, Andrew Morton , Quanmin Yan , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/2] mm/damon/sysfs: set next refresh jiffies per sysfs context Date: Wed, 26 Aug 2026 21:29:19 -0700 Message-ID: <20260827042920.93580-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260827042920.93580-1-sj@kernel.org> References: <20260827042920.93580-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8BB1940005 X-Stat-Signature: h4dgnu4fkqm6ejqfxcen317uucqsic4n X-HE-Tag: 1787804970-208829 X-HE-Meta: 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 9VuJdkUp IoSkyCkL7pwO9sxy3SINhVoofDPutmY3Ld6xYX66sGDRlohZI7n/4AeXixYwMAW9+m7ljuX6pG7hvIKIsSYq1iI9DP8qm0B1ymy57wjUw4zVdShMIH9xlHQcjpBYPEUNSI5M1t+XjFLnkxLH3qGt30P1xAgwucUxLbgyJaFUZOb/I19fRsPHIqz1iJ/Xg2JR3eKgSymBzlgkT5KIIpSXUqN+Yrdg1/eZN3aOxuTQfZ5fwa/I= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When 'refresh_ms' is set, DAMON sysfs interface periodically updates auto-tuned parameters and DAMOS stats. The timestamp for the next refresh is initialized when a DAMON context starts, and updated in its damon_call() callback function. That is, each DAMON context updates it. However, the timestamp is a global variable that is shared with all the contexts. When there are multiple DAMON contexts having different refresh_ms, the update frequency will be changed, depending on the order of the contexts. When there are multiple kdamonds, it will be even more chaotic. Fix the problem by having the timestamp per each context. The user impact is not very critical. It does not leak, corrupt or crash. The update will not be faster or slower than the lowest and largest refresh_ms values of the contexts, respectively. The user can also manually ask the updates on demand using kdamond state commands. That said, clearly this is a bug. Fixes: 9fd7bb5083d1 ("mm/damon/sysfs: change next_update_jiffies to a global variable") Cc: # 6.18.x Signed-off-by: SJ Park --- mm/damon/sysfs.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index e3858ffab4b22..f05b256c90ee7 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1789,6 +1789,7 @@ struct damon_sysfs_kdamond { struct damon_sysfs_contexts *contexts; struct damon_ctx *damon_ctx; unsigned int refresh_ms; + unsigned long next_refresh_jiffies; }; static struct damon_sysfs_kdamond *damon_sysfs_kdamond_alloc(void) @@ -2215,17 +2216,15 @@ static struct damon_ctx *damon_sysfs_build_ctx( return ctx; } -static unsigned long damon_sysfs_next_update_jiffies; - static int damon_sysfs_repeat_call_fn(void *data) { struct damon_sysfs_kdamond *sysfs_kdamond = data; if (!sysfs_kdamond->refresh_ms) return 0; - if (time_before(jiffies, damon_sysfs_next_update_jiffies)) + if (time_before(jiffies, sysfs_kdamond->next_refresh_jiffies)) return 0; - damon_sysfs_next_update_jiffies = jiffies + + sysfs_kdamond->next_refresh_jiffies = jiffies + msecs_to_jiffies(sysfs_kdamond->refresh_ms); if (!mutex_trylock(&damon_sysfs_lock)) @@ -2273,8 +2272,8 @@ static int damon_sysfs_turn_damon_on(struct damon_sysfs_kdamond *kdamond) } kdamond->damon_ctx = ctx; - damon_sysfs_next_update_jiffies = - jiffies + msecs_to_jiffies(kdamond->refresh_ms); + kdamond->next_refresh_jiffies = jiffies + + msecs_to_jiffies(kdamond->refresh_ms); repeat_call_control->fn = damon_sysfs_repeat_call_fn; repeat_call_control->data = kdamond; -- 2.47.3