From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0DF03C07A for ; Mon, 23 Mar 2026 14:20:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774275602; cv=none; b=qiTPcDFi40rhW62CRWgrcnf7PkevFfXHFesznn3WQ8BIXc8WCKyjjTFR03i1RyX3eDyQxVoPds638m8jODZtgZo1HgkXEZRuJ92FXeFdzEKOIihNUJ5WlxVAzERH0AjEJHK0D6ZLVPFRC7+i3AQcXoq0tBLFSP51NOtsik4p41s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774275602; c=relaxed/simple; bh=OUQvRGEelBB7L4nOz1zfbVEpVfhPCan+9hgolp1wUaY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TVa3t7COHhRPo7FvDvtG5WBCKtjLIH/UvvrNlubTTDD8ESDp/ULFBGE3U4WrmQEVCpKZt0r66GxCWEwheeL8krt0fP9L6zgOafM72NLlreTfw3RQRMs4aNkAWyuBVHrhJjRnQbTdlbF9i3Uf3CmX+oIN2YMxjsmYktV1Lexp+dg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=b0dbhedZ; arc=none smtp.client-ip=209.85.214.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="b0dbhedZ" Received: by mail-pl1-f178.google.com with SMTP id d9443c01a7336-2ad617d5b80so28046375ad.1 for ; Mon, 23 Mar 2026 07:20:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1774275601; x=1774880401; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=K7v0kKo5kx/NTKypqvvw5WZo/TwKAYeoO2unauSZDIU=; b=b0dbhedZtqrnz9jnklWj+ezBVd2yiHqjurw0iBDBhoT+dBBcfXqUCymoTEqkjR8QbM sBuwAO3eDoSakOWrHjL4N+B0pijQRocn9zu1ZX1BrZzYJRwpyIg4bobH0DRdsB5C8fG6 TLdlmIVFj2JZwsk9Vj9K3ZzCJ4o4TGYwA66klpBDWKkZ0LMBVTyP0Wd7KUmloh+yrp4B KScUoDltutbw6Mbbfe39/qJKOYs/CsGP9CF/ttDFGP2mUGHJZmwYyN8pLp8mm95yj47S N/4iNHCU0eI/virYA0QRqEaCkKk9QOB6RCZFRuhMHlpqKIzn0kYFsDGE+mx4Uuq8pxLG /5Lg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774275601; x=1774880401; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=K7v0kKo5kx/NTKypqvvw5WZo/TwKAYeoO2unauSZDIU=; b=AIuPjvUBw9sjQhprfFVniok0J7XHQE1qUHLr1ClAsnjbn/7wVtPDTYUQA0rWxUr+6m UV17S8I3jPhX+qpu2IWQorUYAZebAAOZp8eMarzPPI+OkzSr5SjQIdxZEm8IuODYiiB8 iPTjGE95AOqHSgW+TLhBYC8ybmAXc3ZDHWOmF9vjMxU5tYDPjhEGBdpkKlPPeZ6xKk2j b9p1L+ywjWZ0wZvAJZlvJaNJecwF3irxlGBkvLNL2mTeIrxMNHUHBBGQnBKecVhFD7nX 1eSuMwvD9fP8+537nYgFJYa22ecWvgr/d2TtX3e8tJNpVnh3HBIsSyPd6jVcoglDTcX2 ufJQ== X-Gm-Message-State: AOJu0YwV7Ysu7cj/6MsKMIg6AtQ29qrAoN3Bxvi0KpkE037S4/MwT2zi V8V9XXKgjWSyRM0qpWcBFEcHGcQkMEEdvgyYlrqpq9B+iBihCL1m2g0E X-Gm-Gg: ATEYQzx4qut49PXPRFxmOqFpVhUL0TJStMnm6xakKcpC2drbMMg6LShp53Z+gyJthi+ HhLPV5ICCC7KYE9j8EAC7iEuB/peINo5oZfHCC2KglLduAWIWDB2e9JQcoJ73TNEu87sBtsqyfS /jfv43fyj13aAddpfHQx8uKDyAQcRgDke0kXce9H/3ZTkuEHxTNlfKrNtC24TEKmh3DGZh4OQaT +DTABTJIr/WgwPgMj7W2GefFH2FF4YkGySJTqAS7ZrlSg5e4sHNxKTaTAH42MTHp0HkztCc1w1A noWZ8JOpx7O5rTPkfgXa92DcfMCMbzBSmaMw/wpudwgy27MYeXTIjaZBllIhP6zzcVq5I3MbHsE PQzeLHKO/sXG7iZAdc4IdJvAn0HCgUPVnDHW/23F/ErVkZv2uYWKPO90UR4mHRG+tc+7Lslz2I5 6IrPrAATNSB94CzTT0AhKL7j7Vf2A= X-Received: by 2002:a17:903:240e:b0:2b0:60b2:4dc with SMTP id d9443c01a7336-2b082750c20mr127256235ad.15.1774275600873; Mon, 23 Mar 2026 07:20:00 -0700 (PDT) Received: from celestia ([2402:1980:898b:301c:d085:a35:99e7:ffec]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b0836747dcsm107209275ad.64.2026.03.23.07.19.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Mar 2026 07:20:00 -0700 (PDT) From: Liew Rui Yan To: sj@kernel.org Cc: damon@lists.linux.dev, linux-mm@kvack.org, aethernet65535@gmail.com Subject: Re: [RFC v4] mm/damon: add synchronous commit for commit_inputs Date: Mon, 23 Mar 2026 22:19:55 +0800 Message-ID: <20260323141955.20535-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323072724.15942-1-aethernet65535@gmail.com> References: <20260323072724.15942-1-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 Hi SeongJae, Follow-up on my previous email regarding the locking concerns. > I admit I don't have an elegant solution yet. Here are my current > thought: > > Add a timeout to wait_for_completion() (e.g., > wait_for_completion_timeout()), using 'damos_watermarks.interval' as the > upper bound. This prevents indefinite blocking of 'param_lock', though > it still holds the global lock for up to several seconds. After further analysis, I realized that since both 'commit_inputs' and 'enabled' module parameters are protected by the global 'param_lock', stopping kdamond gracefully (via enabled=N) is serialized with 'commit_inputs' writes. Therefore, a classic deadlock scenario should not occur in normal operation. However, I'm considering edge cases where kdamond might terminate unexpectedly. In such cases, commit_inputs_store() could hold 'param_lock' indefinitely, blocking other module parameter updates system-wide. To mitigate this risk defensively, would you accept adding a timeout to wait_for_completion()? This ensures 'param_lock' is eventually released even if kdamond fails unexpectedly. Please let me know your preference. :> Best regards, Rui Yan