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b=ONQUSt83ZZf7rEbmIESSsiSQY3xMN39a3j6xObv5wd/XdtB/jXcxKdMubi9fe5Yu1 h8udRMs5vsU70vf9oSVc5EGY3fc750jeT7FoRPmc/08YkG1aXEj4IL9INAk2HtbgVc EQmH5KBU7pLDLRkQMyv5MGprvN0nAH+jY7ZC8M3k= Date: Sat, 5 Sep 2026 15:37:04 -0700 From: Andrew Morton To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Baoquan He , LKML , stable@vger.kernel.org, Dev Jain , Ye Liu , lirongqing Subject: Re: [PATCH RESEND] mm/vmalloc: Use dedicated unbound workqueues for vmap drain Message-Id: <20260905153704.e7fe650d0226c3e20c1c8449@linux-foundation.org> In-Reply-To: <20260905152717.11711-1-urezki@gmail.com> References: <20260905152717.11711-1-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: rspam04 X-Rspamd-Queue-Id: 89B51140003 X-Stat-Signature: 4rjeupahfns1fxhu859k47s7y7dqypp1 X-HE-Tag: 1788647826-45094 X-HE-Meta: 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 cFzWEc8g yO9g0O8DA2lhCntuFJGAocHncvqr8s+ExXlfWdjPK/mmSiNO9LCozcQT/Hgm0p36AmIysqeH9jtnf26p762F96auW9zqWjBc0FoHz0syoBLd37bA8YGMc1mL/oBkj7aOzqihOFX3Ro2lB7sMG22lrFZGYpWyXL83fiMHLMemjNXfb0MtbrzIZVteLzzfR3obvDad48H8nx7WZEv+6VJD+HH1B6NI3qD1iZHQrXG3V3kN7mruZoaLUURehggXih+fyVL/15XTg9CWyqFkWXnLob2cde5RwRqmFmNW0yyfYLk75QSN0vZGZRBkZBp5H4MtYTGZ+pbkIOwfBFKLRqKahVyIxanTt4vQQHGycN0jtI9NQ0Az9ObQqHIayxLi5LUkeThuQjDPVbUixoYXQZs2hzUYSZw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 5 Sep 2026 17:27:17 +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. Thanks. > Cc: stable@vger.kernel.org > Cc: Dev Jain > Cc: Ye Liu > Cc: lirongqing > Fixes: 72210662c5a2 ("mm: vmalloc: offload free_vmap_area_lock lock") > Link: https://lore.kernel.org/all/20260319074307.2325-1-lirongqing@baidu.com/ > Reviewed-by: Baoquan He > Signed-off-by: Uladzislau Rezki (Sony) I think what we wanted here was Reported-by: Li RongQing Closes: https://lore.kernel.org/all/20260319074307.2325-1-lirongqing@baidu.com/ so I made that change.