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 26D9123EAB3 for ; Fri, 20 Mar 2026 03:16:18 +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=1773976579; cv=none; b=BJLl2i5w0uCz3ZV6+kTsjyxOJKJd5mK6JthuqD2OXBf+CCQa7Ma9Y+9kwGoeooTz9Aoico3bqrIhAnWFuqMTHuhk8AFBBqWz1Hj4Ho/fCg3vNTOJdWn76BSt0tITNe+3ox43X5HIfIbc1yzpJcGA/BrX6huvFjHTgF5+NnM8E0E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773976579; c=relaxed/simple; bh=ghZRuCo0i0hEdBUwHMzlyAVKjwiFMQ4X15pR6D2bBe0=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=OyY9iXAk9oiPdM5RosXjKpHEh8odNs8xK2JSceFzBOX8WWYgmUfvARC4Ylt+bLs9SdR5XNMW2haeSFA0Mty6AoBqx2zgQNEZv8WmJY1PRsOvNwQoUjbUyyvL43CFUBTQR7iqf/9lpq7YScs+OBbsaG6aNMsh64IOZnrHNcu58Gg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=RQ+iyGLk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="RQ+iyGLk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE3C4C19424; Fri, 20 Mar 2026 03:16:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773976578; bh=ghZRuCo0i0hEdBUwHMzlyAVKjwiFMQ4X15pR6D2bBe0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RQ+iyGLkoPUh3ZeZSnBBL3z2gg76R5vaufFNWDqrzdPTVnYM005Zp8yPUJ2JcuTw1 qVSQWxgiB8y9oRDRRe7DZCUqvRY/Ok/F9v5TSUGTYTk/+v2a6pCtFVD9qgUu+A+Cnh sBE+AJjP3Zx/SuDQarU6tHqJ4tmCrftgH1FiKP40= Date: Thu, 19 Mar 2026 20:16:18 -0700 From: Andrew Morton To: lirongqing Cc: Uladzislau Rezki , , Subject: Re: [PATCH v2] mm/vmalloc: use dedicated unbound workqueue for vmap area draining Message-Id: <20260319201618.487dab7d56fb31adda6bdbfa@linux-foundation.org> In-Reply-To: <20260319074307.2325-1-lirongqing@baidu.com> References: <20260319074307.2325-1-lirongqing@baidu.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 19 Mar 2026 03:43:07 -0400 lirongqing wrote: > The drain_vmap_area_work() function can take >10ms to complete when > there are many accumulated vmap areas in a system with a high CPU > count, causing workqueue watchdog warnings when run via > schedule_work(): > > [ 2069.796205] workqueue: drain_vmap_area_work hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND > [ 2192.823225] workqueue: drain_vmap_area_work hogged CPU for >10000us 5 times, consider switching to WQ_UNBOUND > > Switch to a dedicated WQ_UNBOUND workqueue to allow the scheduler to > run this background task on any available CPU, improving responsiveness. > Use WQ_MEM_RECLAIM to ensure forward progress under memory pressure. > > Create vmap_drain_wq in vmalloc_init_late() which is called after > workqueue_init_early() in start_kernel() to avoid boot-time crashes. AI review flags some potential issues: https://sashiko.dev/#/patchset/20260319074307.2325-1-lirongqing%40baidu.com