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Thu, 02 Apr 2026 09:06:14 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 2 Apr 2026 18:06:13 +0200 To: Baoquan He Cc: "Uladzislau Rezki (Sony)" , linux-mm@kvack.org, Andrew Morton , LKML , stable@vger.kernel.org, lirongqing Subject: Re: [PATCH v3] mm/vmalloc: Use dedicated unbound workqueues for vmap drain Message-ID: References: <20260331202352.879718-1-urezki@gmail.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Apr 02, 2026 at 08:23:10AM +0800, Baoquan He wrote: > On 03/31/26 at 10:23pm, 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. > > > > Cc: stable@vger.kernel.org > > Cc: lirongqing > > Fixes: 72210662c5a2 ("mm: vmalloc: offload free_vmap_area_lock lock") > > Link: https://lore.kernel.org/all/20260319074307.2325-1-lirongqing@baidu.com/ > > Signed-off-by: Uladzislau Rezki (Sony) > > --- > > mm/vmalloc.c | 79 ++++++++++++++++++++++++++++++++++------------------ > > 1 file changed, 52 insertions(+), 27 deletions(-) > > LGTM, > > Reviewed-by: Baoquan He > Thanks! -- Uladzislau Rezki