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Tue, 08 Sep 2026 07:23:36 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 8 Sep 2026 16:23:30 +0200 To: Andrew Morton Cc: "Uladzislau Rezki (Sony)" , 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: References: <20260905152717.11711-1-urezki@gmail.com> <20260905153704.e7fe650d0226c3e20c1c8449@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260905153704.e7fe650d0226c3e20c1c8449@linux-foundation.org> On Sat, Sep 05, 2026 at 03:37:04PM -0700, Andrew Morton wrote: > 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. > Yep :) Thank you! -- Uladzislau Rezki