From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f200.google.com (mail-ig0-f200.google.com [209.85.213.200]) by kanga.kvack.org (Postfix) with ESMTP id 2DD886B0005 for ; Sun, 5 Jun 2016 14:42:00 -0400 (EDT) Received: by mail-ig0-f200.google.com with SMTP id lp2so80074711igb.3 for ; Sun, 05 Jun 2016 11:42:00 -0700 (PDT) Received: from mail-oi0-x244.google.com (mail-oi0-x244.google.com. [2607:f8b0:4003:c06::244]) by mx.google.com with ESMTPS id v66si3640559oig.116.2016.06.05.11.41.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 05 Jun 2016 11:41:59 -0700 (PDT) Received: by mail-oi0-x244.google.com with SMTP id r4so1857255oib.1 for ; Sun, 05 Jun 2016 11:41:59 -0700 (PDT) Date: Sun, 5 Jun 2016 13:41:57 -0500 From: Tejun Heo Subject: Re: [PATCH v2] mm: Introduce dedicated WQ_MEM_RECLAIM workqueue to do lru_add_drain_all Message-ID: <20160605184157.GT31708@htj.duckdns.org> References: <1464917521-9775-1-git-send-email-shhuiw@foxmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1464917521-9775-1-git-send-email-shhuiw@foxmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Wang Sheng-Hui Cc: keith.busch@intel.com, peterz@infradead.org, treding@nvidia.com, mingo@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org On Fri, Jun 03, 2016 at 09:32:01AM +0800, Wang Sheng-Hui wrote: > This patch is based on https://patchwork.ozlabs.org/patch/574623/. > > Tejun submitted commit 23d11a58a9a6 ("workqueue: skip flush dependency > checks for legacy workqueues") for the legacy create*_workqueue() > interface. But some workq created by alloc_workqueue still reports > warning on memory reclaim, e.g nvme_workq with flag WQ_MEM_RECLAIM set: > > [ 0.153902] workqueue: WQ_MEM_RECLAIM nvme:nvme_reset_work is > flushing !WQ_MEM_RECLAIM events:lru_add_drain_per_cpu > [ 0.153907] ------------[ cut here ]------------ > [ 0.153912] WARNING: CPU: 0 PID: 6 at > SoC/linux/kernel/workqueue.c:2448 > check_flush_dependency+0xb4/0x10c > ... > [ 0.154083] [] check_flush_dependency+0xb4/0x10c > [ 0.154088] [] flush_work+0x54/0x140 > [ 0.154092] [] lru_add_drain_all+0x138/0x188 > [ 0.154097] [] migrate_prep+0xc/0x18 > [ 0.154101] [] alloc_contig_range+0xf4/0x350 > [ 0.154105] [] cma_alloc+0xec/0x1e4 > [ 0.154110] [] dma_alloc_from_contiguous+0x38/0x40 > [ 0.154114] [] __dma_alloc+0x74/0x25c > [ 0.154119] [] nvme_alloc_queue+0xcc/0x36c > [ 0.154123] [] nvme_reset_work+0x5c4/0xda8 > [ 0.154128] [] process_one_work+0x128/0x2ec > [ 0.154132] [] worker_thread+0x58/0x434 > [ 0.154136] [] kthread+0xd4/0xe8 > [ 0.154141] [] ret_from_fork+0x10/0x50 > > That's because lru_add_drain_all() will schedule the drain work on > system_wq, whose flag is set to 0, !WQ_MEM_RECLAIM. > > Introduce a dedicated WQ_MEM_RECLAIM workqueue to do lru_add_drain_all(), > aiding in getting memory freed. > > Compared with v1: > * The key flag is WQ_MEM_RECLAIM. Drop the flag WQ_UNBOUND. > * Reserve the warn in lru_init as init code during bootup ignore > return code from early_initcall functions. > * Instead of falling back to system_wq, crash directly if the wq > is used in lru_add_drain_all but was not created in lru_init > at init stage. > > Signed-off-by: Wang Sheng-Hui Acked-by: Tejun Heo Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org