From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f69.google.com (mail-it0-f69.google.com [209.85.214.69]) by kanga.kvack.org (Postfix) with ESMTP id A8B076B0033 for ; Sun, 26 Nov 2017 03:04:00 -0500 (EST) Received: by mail-it0-f69.google.com with SMTP id p144so9823243itc.9 for ; Sun, 26 Nov 2017 00:04:00 -0800 (PST) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id p125si11535326ite.42.2017.11.26.00.03.58 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sun, 26 Nov 2017 00:03:58 -0800 (PST) Subject: Re: [PATCH] mm: print a warning once the vm dirtiness settings is illogical From: Tetsuo Handa References: <1506592464-30962-1-git-send-email-laoar.shao@gmail.com> <201711261142.EIE82842.LFOtSHOFVOFJQM@I-love.SAKURA.ne.jp> In-Reply-To: Message-Id: <201711261703.HDI52138.JSFVOFOtHLMOFQ@I-love.SAKURA.ne.jp> Date: Sun, 26 Nov 2017 17:03:49 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: laoar.shao@gmail.com Cc: akpm@linux-foundation.org, jack@suse.cz, mhocko@suse.com, linux-mm@kvack.org Yafang Shao wrote: > >> I have also verified your test code on my machine, but can not find > >> this message. > >> > > > > Not always printed. It is timing dependent. > > > > I will try and analysis why this happen. > I see. Here is dump of variables. Always mostly 0 when this happens. --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -434,7 +434,8 @@ static void domain_dirty_limits(struct dirty_throttle_control *dtc) bg_thresh = (bg_ratio * available_memory) / PAGE_SIZE; if (unlikely(bg_thresh >= thresh)) { - pr_warn("vm direct limit must be set greater than background limit.\n"); + pr_warn("vm direct limit must be set greater than background limit. bg_thresh=%lu thresh=%lu bg_bytes=%lu bytes=%lu bg_ratio=%lu ratio=%lu gdtc=%p gdtc->vail=%lu vm_dirty_bytes=%lu dirty_background_bytes=%lu\n", + bg_thresh, thresh, bg_bytes, bytes, bg_ratio, ratio, gdtc, gdtc ? gdtc->avail : 0UL, vm_dirty_bytes, dirty_background_bytes); bg_thresh = thresh / 2; } [ 259.641324] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 317.798913] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 317.798935] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 317.976210] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 417.781194] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 466.322615] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 466.322618] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 466.497893] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 [ 466.504687] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0 -- 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