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b=wNT35w/vw8xWsD/40fdXn5qc9f0rBOKnU6X48i8mSooOyOfijeLu3kEYts46pIyKe ei6FPh3502BrQiCMZOvAc7esofUiL4PysrOwbE1Qw4vhTO24C2li4kwdUnNSzkRC1r taTbKOXEtY28t2ZBhhL+VepThvLN2OnPxzQSIpEI= Date: Mon, 30 Mar 2026 12:16:25 -0700 From: Andrew Morton To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Baoquan He , LKML , lirongqing Subject: Re: [PATCH v2] mm/vmalloc: Use dedicated unbound workqueue for vmap purge/drain Message-Id: <20260330121625.c69f46a63c86c9540b823398@linux-foundation.org> In-Reply-To: <20260330175824.2777270-1-urezki@gmail.com> References: <20260330175824.2777270-1-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-Rspamd-Queue-Id: C0ADD2000B X-Stat-Signature: bwfhbs7ph7ze4cji4pcyg865nt9tr4s4 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1774898186-169355 X-HE-Meta: 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 NtlkQjug a881d9aLxNOH5jIzWGYGCzZUTxwlOMDBFQ2tqxHod5NHeTzS3kYzbY//p1JmBr1rkljwm47rdsCN0YKWzrW3wEjy0HI/WYMPls87IYhtw+26+BVYPvOUkvurKPCpfJjnrVNfkGKSvY4Nc5FxV/nl6kHbEtu2J1BzNt8LLX8lp5hYdaBtmZFD+u0xhhYHKMI6CLaUr9U6DOKKX8Cv2xYXHr+RYnwPcPwNQRzfjSAv4aX100EfLa59qs5ubQeda7PjtHa4fE2i/50Utgo829FlG6s2Ti/vAxBy7YW8CznHyxtrL9nAbaB5dHNHB8JMTNmyhGBP6xmW15xtlpDg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 30 Mar 2026 19:58:24 +0200 "Uladzislau Rezki (Sony)" 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. > > If queuing work to the dedicated workqueue is not possible(during > early boot), fall back to processing locally to avoid losing progress. > > Also simplify purge helper scheduling by removing cpumask-based > iteration in favour to iterating directly over vmap nodes with > pending work. Thanks. AI review flagged a couple of possible issues. Do they look real to you? https://sashiko.dev/#/patchset/20260330175824.2777270-1-urezki@gmail.com