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bh=IFD7WZgFJWD+7FI2n24DlTa/YBUWCJoLQWxKiC5cH+Q=; b=kVh0OyykNsIW5PuuHAeuHPQc4d13wi5KbF1DK8hLF95MPKiD+R4Z0m74vOc92Wsns3W71y anXqNMm123YiKhDOa8bWiOxP7ocvlMpqwfsbKFIlSQpOTwuAztPW/E2o8PyHPlm6qeCeDF pqyETHP4RGpFz7q1Afls1w0idbOtKSM= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=E2lmhWqJ; spf=pass (imf12.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id CA27D4330F; Tue, 31 Mar 2026 22:40:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DA53C19423; Tue, 31 Mar 2026 22:40:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1774996806; bh=rl4/17UJ02DrCORAEhhWxTz7VUCl9Xg85++OigKCpx0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=E2lmhWqJngQkNc0t2bSGmbkbQ9CydxkrIfPDRpvweyNCbhBotNOv0k3eKUBcWEuYz 1EJCKHKdVMSa1Zc1Irfvpi5sOeF+xnv6TYAYOGgSPHveAttww4OWnJ4zmjNfUAzHgg J1OWpqsoljMNSc1t9GEHp4YIxsDWTajqizST3nws= Date: Tue, 31 Mar 2026 15:40:05 -0700 From: Andrew Morton To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Baoquan He , LKML , stable@vger.kernel.org, lirongqing Subject: Re: [PATCH v3] mm/vmalloc: Use dedicated unbound workqueues for vmap drain Message-Id: <20260331154005.4471389e14061f467ab1e433@linux-foundation.org> In-Reply-To: <20260331202352.879718-1-urezki@gmail.com> References: <20260331202352.879718-1-urezki@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: DEDA440006 X-Stat-Signature: qfyft67s49bscybbi4itfbuzpcwsysah X-HE-Tag: 1774996807-821344 X-HE-Meta: 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 aYB52GQS 9p38AbTZ/+HNbds8mY8Fgg6zhu3CUz/zDHPkCnuxJBfUVZev8yH7YcQb51ioPHyS4WPWCMjAmMUzEBHekyrQtjZ3hshAC5pLQM36l5xuXM+KWH71oefw17l36iXCMqSeelsAzNt9HEOAbhp8QZwdAgp9Ctvic4szRZzev8PGxrah0TSJnaucOvYApVsAaLoUhHYgDRMe74T2xsixHSv/BBCOH/FwXsVbdxyySQWx3tcgWvxA3AyRTKveA4WxkFxp2h5IE5Uwh/RyrIQk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 31 Mar 2026 22:23:52 +0200 "Uladzislau Rezki (Sony)" wrote: > drain_vmap_area_work() function can take >10ms to complete > when there are many accumulated vmap areas in a system with > high CPU count, causing workqueue watchdog warnings when run > via schedule_work(): > > workqueue: drain_vmap_area_work hogged CPU for >10000us > > Move the top-level drain work to a dedicated WQ_UNBOUND > workqueue so the scheduler can run this background work > on any available CPU, improving responsiveness. Use the > WQ_MEM_RECLAIM to ensure forward progress under memory > pressure. > > Move purge helpers to separate WQ_UNBOUND | WQ_MEM_RECLAIM > workqueue. This allows drain_vmap_work to wait for helpers > completion without creating dependency on the same rescuer > thread and avoid a potential parent/child deadlock. > > Simplify purge helper scheduling by removing cpumask-based > iteration to iterating directly over vmap nodes checking > work_queued state. Great, thanks. > Fixes: 72210662c5a2 ("mm: vmalloc: offload free_vmap_area_lock lock") That was a couple of years ago so I see no need to rush this into mainline. I added it to the next-merge-window pile - it'll trickle back into -stable kernels later on.