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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260905153704.e7fe650d0226c3e20c1c8449@linux-foundation.org> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 73EA214000F X-Stat-Signature: 3d8miiss1hhff4ijbgwg59o5f75z16zj X-Rspam-User: X-HE-Tag: 1788877418-894086 X-HE-Meta: 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 1VU+aemp 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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