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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) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: xmag8xzzoso6gffmyr7dt88rz8bk7i5e X-Rspamd-Queue-Id: CDA89C0002 X-Rspamd-Server: rspam03 X-HE-Tag: 1773976579-965039 X-HE-Meta: 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 WPySBIVC MFo7R633dvhF2XK4E09VcOaBnK8FpjbBS5dMM+2MHQQScwgcokqBuKW6X1d+SPLiMr+U7HUrwJZ5Vhz5kSrHaYSs12ZaeDUZjMddNJSWinmouahrWwdUkin5IRUJhaOzveQnh6svk5WSFk5002jaAvkR3Vo35t0ervwlJ1xI0xH0LXHOmVLLNie/NWe0761F10zNPPCCVLvRvvOEoAOK4v5vBIfkKRuFcOo1lsr39kapSeQS7MgE06oopsoCs/jsRPD6/BWGMHcj1aI+WV4SFrPWt9G+lHto1Pf/fNb1GZDqX47c= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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