From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16117C433E0 for ; Fri, 12 Jun 2020 07:40:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 918ED207ED for ; Fri, 12 Jun 2020 07:40:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IiNFkc/t" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 918ED207ED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E40338D00B2; Fri, 12 Jun 2020 03:40:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DF1088D00A0; Fri, 12 Jun 2020 03:40:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CB7A78D00B2; Fri, 12 Jun 2020 03:40:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0120.hostedemail.com [216.40.44.120]) by kanga.kvack.org (Postfix) with ESMTP id AFF848D00A0 for ; Fri, 12 Jun 2020 03:40:46 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 73E32180AD822 for ; Fri, 12 Jun 2020 07:40:46 +0000 (UTC) X-FDA: 76919762892.22.cat80_1a113b226dda Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 49B7018038E68 for ; Fri, 12 Jun 2020 07:40:46 +0000 (UTC) X-HE-Tag: cat80_1a113b226dda X-Filterd-Recvd-Size: 17065 Received: from mail-pl1-f195.google.com (mail-pl1-f195.google.com [209.85.214.195]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Fri, 12 Jun 2020 07:40:45 +0000 (UTC) Received: by mail-pl1-f195.google.com with SMTP id y18so3419762plr.4 for ; Fri, 12 Jun 2020 00:40:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=cr9Tb2uFsFTM7LZhZWJK1JlmYSI+amTKUTLrXWk+3fA=; b=IiNFkc/t1kSYckjS9WWP58nqs6MWOM1IQXJZKSYANf4t7VUU/w2Vw1OzfGhMPuTbGk KMD04putW3X0ywhaskAZV5JHOF3I9c/RWyWNoNElc3ez9E6/OVMWeFzukNy4rqD6MKGd Qd8UzqCMm8Q1RlJKXjl0Tfufx1l3/3oZcLEipEiPRHhGHM5YM51l5Qy6x7MsjhBvmIE4 lqHR9uoLFiwea6nosie5ZVaSmCXccEywrfmhSN5+pmuyIFTX3HKK+1+CpejaaK3B9FGD lwJC6FaBsgO6Xa2YvrO5Y7x4tmNt/1uCafsOxcqdDMB8/NzQjQ/irD6/kCZTIs8q6Olk uMAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to; bh=cr9Tb2uFsFTM7LZhZWJK1JlmYSI+amTKUTLrXWk+3fA=; b=QY5uzGqgUMKX5gRBEUxd3wup8bcCZV5cLUxPSGw2z5iCkkoOjiLK38FOrhx3hqn82W EyQVfPBazC2Z7ritdu2Mg/DFGcUzxxuIfOGKZdbR+T8yhIqulH0Oxb/UnCmFSN0csF9L 9z4BxpO4RkXYs8p5S+CoC8yJxZfWOTBhSnPH7Z68dQG4ZOmgdC5nXtmQr1LKl2YAYm0W MPI0YaEMVVbkmyz4nIqJgcYqbvITekPLE0Yz4kaxQHreudQ0hQhR2376FrjIfrOTtOWT Gi4QQZxqWf9sTJoojoOL5AwhNVRTWOF/BXz3W4rLHMx2R5iwrk2I/OMvYkzeZA98XmHz YK/w== X-Gm-Message-State: AOAM533QiCLleCCoj5l9CBcAG9GbqwO6Tlvzv71anhNykVzFpbwrqdT3 qYIkwFMzyle8LgQuzpnSiiE= X-Google-Smtp-Source: ABdhPJyXQYSfRPwicHukfg8cMUOlgHXFS1R6EP5Sbi34exhfEz9K3C8N0phuXnh6pUYhXDDF1bjNKA== X-Received: by 2002:a17:902:b203:: with SMTP id t3mr10581079plr.129.1591947644184; Fri, 12 Jun 2020 00:40:44 -0700 (PDT) Received: from google.com ([2601:647:4001:3000::e690]) by smtp.gmail.com with ESMTPSA id q6sm5214273pff.163.2020.06.12.00.40.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jun 2020 00:40:42 -0700 (PDT) Date: Fri, 12 Jun 2020 00:40:40 -0700 From: Minchan Kim To: Jaewon Kim Cc: mgorman@techsingularity.net, mgorman@suse.de, hannes@cmpxchg.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com, ytk.lee@samsung.com, cmlaika.kim@samsung.com Subject: Re: [PATCH] page_alloc: consider highatomic reserve in wmartermark fast Message-ID: <20200612074040.GA98223@google.com> References: <20200609095128.8112-1-jaewon31.kim@samsung.com> <20200610012112.GA239587@google.com> <5EE1F134.4090001@samsung.com> <20200612065523.GA92598@google.com> <5EE328CD.2060100@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5EE328CD.2060100@samsung.com> X-Rspamd-Queue-Id: 49B7018038E68 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jun 12, 2020 at 04:03:41PM +0900, Jaewon Kim wrote: >=20 >=20 > On 2020=EB=85=84 06=EC=9B=94 12=EC=9D=BC 15:55, Minchan Kim wrote: > > On Thu, Jun 11, 2020 at 05:54:12PM +0900, Jaewon Kim wrote: > >> > >> On 2020=EB=85=84 06=EC=9B=94 10=EC=9D=BC 10:21, Minchan Kim wrote: > >>> Hi Jaewon, > >>> > >>> On Tue, Jun 09, 2020 at 06:51:28PM +0900, Jaewon Kim wrote: > >>>> zone_watermark_fast was introduced by commit 48ee5f3696f6 ("mm, > >>>> page_alloc: shortcut watermark checks for order-0 pages"). The com= mit > >>>> simply checks if free pages is bigger than watermark without addit= ional > >>>> calculation such like reducing watermark. > >>>> > >>>> It considered free cma pages but it did not consider highatomic > >>>> reserved. This may incur exhaustion of free pages except high orde= r > >>>> atomic free pages. > >>>> > >>>> Assume that reserved_highatomic pageblock is bigger than watermark= min, > >>>> and there are only few free pages except high order atomic free. B= ecause > >>>> zone_watermark_fast passes the allocation without considering high= order > >>>> atomic free, normal reclaimable allocation like GFP_HIGHUSER will > >>>> consume all the free pages. Then finally order-0 atomic allocation= may > >>>> fail on allocation. > >>>> > >>>> This means watermark min is not protected against non-atomic alloc= ation. > >>>> The order-0 atomic allocation with ALLOC_HARDER unwantedly can be > >>>> failed. Additionally the __GFP_MEMALLOC allocation with > >>>> ALLOC_NO_WATERMARKS also can be failed. > >>>> > >>>> To avoid the problem, zone_watermark_fast should consider highatom= ic > >>>> reserve. If the actual size of high atomic free is counted accurat= ely > >>>> like cma free, we may use it. On this patch just use > >>>> nr_reserved_highatomic. > >>>> > >>>> This is trace log which shows GFP_HIGHUSER consumes free pages rig= ht > >>>> before ALLOC_NO_WATERMARKS. > >>>> > >>>> <...>-22275 [006] .... 889.213383: mm_page_alloc: page=3D00000= 000d2be5665 pfn=3D970744 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213385: mm_page_alloc: page=3D00000= 0004b2335c2 pfn=3D970745 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213387: mm_page_alloc: page=3D00000= 000017272e1 pfn=3D970278 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213389: mm_page_alloc: page=3D00000= 000c4be79fb pfn=3D970279 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213391: mm_page_alloc: page=3D00000= 000f8a51d4f pfn=3D970260 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213393: mm_page_alloc: page=3D00000= 0006ba8f5ac pfn=3D970261 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213395: mm_page_alloc: page=3D00000= 000819f1cd3 pfn=3D970196 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> <...>-22275 [006] .... 889.213396: mm_page_alloc: page=3D00000= 000f6b72a64 pfn=3D970197 order=3D0 migratetype=3D0 nr_free=3D3650 gfp_fla= gs=3DGFP_HIGHUSER|__GFP_ZERO > >>>> kswapd0-1207 [005] ...1 889.213398: mm_page_alloc: page=3D (nul= l) pfn=3D0 order=3D0 migratetype=3D1 nr_free=3D3650 gfp_flags=3DGFP_NOWAI= T|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_MOVABLE > >>>> > >>>> This is an example of ALLOC_HARDER allocation failure. > >>>> > >>>> <4>[ 6207.637280] [3: Binder:9343_3:22875] Binder:9343_3: page a= llocation failure: order:0, mode:0x480020(GFP_ATOMIC), nodemask=3D(null) > >>>> <4>[ 6207.637311] [3: Binder:9343_3:22875] Call trace: > >>>> <4>[ 6207.637346] [3: Binder:9343_3:22875] [] = dump_stack+0xb8/0xf0 > >>>> <4>[ 6207.637356] [3: Binder:9343_3:22875] [] = warn_alloc+0xd8/0x12c > >>>> <4>[ 6207.637365] [3: Binder:9343_3:22875] [] = __alloc_pages_nodemask+0x120c/0x1250 > >>>> <4>[ 6207.637374] [3: Binder:9343_3:22875] [] = new_slab+0x128/0x604 > >>>> <4>[ 6207.637381] [3: Binder:9343_3:22875] [] = ___slab_alloc+0x508/0x670 > >>>> <4>[ 6207.637387] [3: Binder:9343_3:22875] [] = __kmalloc+0x2f8/0x310 > >>>> <4>[ 6207.637396] [3: Binder:9343_3:22875] [] = context_struct_to_string+0x104/0x1cc > >>>> <4>[ 6207.637404] [3: Binder:9343_3:22875] [] = security_sid_to_context_core+0x74/0x144 > >>>> <4>[ 6207.637412] [3: Binder:9343_3:22875] [] = security_sid_to_context+0x10/0x18 > >>>> <4>[ 6207.637421] [3: Binder:9343_3:22875] [] = selinux_secid_to_secctx+0x20/0x28 > >>>> <4>[ 6207.637430] [3: Binder:9343_3:22875] [] = security_secid_to_secctx+0x3c/0x70 > >>>> <4>[ 6207.637442] [3: Binder:9343_3:22875] [] = binder_transaction+0xe68/0x454c > >>>> <4>[ 6207.637569] [3: Binder:9343_3:22875] Mem-Info: > >>>> <4>[ 6207.637595] [3: Binder:9343_3:22875] active_anon:102061 in= active_anon:81551 isolated_anon:0 > >>>> <4>[ 6207.637595] [3: Binder:9343_3:22875] active_file:59102 in= active_file:68924 isolated_file:64 > >>>> <4>[ 6207.637595] [3: Binder:9343_3:22875] unevictable:611 dirt= y:63 writeback:0 unstable:0 > >>>> <4>[ 6207.637595] [3: Binder:9343_3:22875] slab_reclaimable:133= 24 slab_unreclaimable:44354 > >>>> <4>[ 6207.637595] [3: Binder:9343_3:22875] mapped:83015 shmem:4= 858 pagetables:26316 bounce:0 > >>>> <4>[ 6207.637595] [3: Binder:9343_3:22875] free:2727 free_pcp:1= 035 free_cma:178 > >>>> <4>[ 6207.637616] [3: Binder:9343_3:22875] Node 0 active_anon:40= 8244kB inactive_anon:326204kB active_file:236408kB inactive_file:275696kB= unevictable:2444kB isolated(anon):0kB isolated(file):256kB mapped:332060= kB dirty:252kB writeback:0kB shmem:19432kB writeback_tmp:0kB unstable:0kB= all_unreclaimable? no > >>>> <4>[ 6207.637627] [3: Binder:9343_3:22875] Normal free:10908kB m= in:6192kB low:44388kB high:47060kB active_anon:409160kB inactive_anon:325= 924kB active_file:235820kB inactive_file:276628kB unevictable:2444kB writ= epending:252kB present:3076096kB managed:2673676kB mlocked:2444kB kernel_= stack:62512kB pagetables:105264kB bounce:0kB free_pcp:4140kB local_pcp:40= kB free_cma:712kB > >>>> <4>[ 6207.637632] [3: Binder:9343_3:22875] lowmem_reserve[]: 0 0 > >>>> <4>[ 6207.637637] [3: Binder:9343_3:22875] Normal: 505*4kB (H) 3= 57*8kB (H) 201*16kB (H) 65*32kB (H) 1*64kB (H) 0*128kB 0*256kB 0*512kB 0*= 1024kB 0*2048kB 0*4096kB =3D 10236kB > >>>> <4>[ 6207.637655] [3: Binder:9343_3:22875] 138826 total pagecach= e pages > >>>> <4>[ 6207.637663] [3: Binder:9343_3:22875] 5460 pages in swap ca= che > >>>> <4>[ 6207.637668] [3: Binder:9343_3:22875] Swap cache stats: add= 8273090, delete 8267506, find 1004381/4060142 > >>>> > >>>> This is an example of ALLOC_NO_WATERMARKS allocation failure. > >>>> > >>>> <6>[ 156.701551] [4: kswapd0: 1209] kswapd0 cpuset=3D/ me= ms_allowed=3D0 > >>>> <4>[ 156.701563] [4: kswapd0: 1209] CPU: 4 PID: 1209 Comm= : kswapd0 Tainted: G W 4.14.113-18113966 #1 > >>>> <4>[ 156.701572] [4: kswapd0: 1209] Call trace: > >>>> <4>[ 156.701605] [4: kswapd0: 1209] [<0000000000000000>] = dump_stack+0x68/0x90 > >>>> <4>[ 156.701612] [4: kswapd0: 1209] [<0000000000000000>] = warn_alloc+0x104/0x198 > >>>> <4>[ 156.701617] [4: kswapd0: 1209] [<0000000000000000>] = __alloc_pages_nodemask+0xdc0/0xdf0 > >>>> <4>[ 156.701623] [4: kswapd0: 1209] [<0000000000000000>] = zs_malloc+0x148/0x3d0 > >>>> <4>[ 156.701630] [4: kswapd0: 1209] [<0000000000000000>] = zram_bvec_rw+0x250/0x568 > >>>> <4>[ 156.701634] [4: kswapd0: 1209] [<0000000000000000>] = zram_rw_page+0x8c/0xe0 > >>>> <4>[ 156.701640] [4: kswapd0: 1209] [<0000000000000000>] = bdev_write_page+0x70/0xbc > >>>> <4>[ 156.701645] [4: kswapd0: 1209] [<0000000000000000>] = __swap_writepage+0x58/0x37c > >>>> <4>[ 156.701649] [4: kswapd0: 1209] [<0000000000000000>] = swap_writepage+0x40/0x4c > >>>> <4>[ 156.701654] [4: kswapd0: 1209] [<0000000000000000>] = shrink_page_list+0xc3c/0xf54 > >>>> <4>[ 156.701659] [4: kswapd0: 1209] [<0000000000000000>] = shrink_inactive_list+0x2b0/0x61c > >>>> <4>[ 156.701664] [4: kswapd0: 1209] [<0000000000000000>] = shrink_node_memcg+0x23c/0x618 > >>>> <4>[ 156.701668] [4: kswapd0: 1209] [<0000000000000000>] = shrink_node+0x1c8/0x304 > >>>> <4>[ 156.701673] [4: kswapd0: 1209] [<0000000000000000>] = kswapd+0x680/0x7c4 > >>>> <4>[ 156.701679] [4: kswapd0: 1209] [<0000000000000000>] = kthread+0x110/0x120 > >>>> <4>[ 156.701684] [4: kswapd0: 1209] [<0000000000000000>] = ret_from_fork+0x10/0x18 > >>>> <4>[ 156.701689] [4: kswapd0: 1209] Mem-Info: > >>>> <4>[ 156.701712] [4: kswapd0: 1209] active_anon:88690 ina= ctive_anon:88630 isolated_anon:0 > >>>> <4>[ 156.701712] [4: kswapd0: 1209] active_file:99173 in= active_file:169305 isolated_file:32 > >>>> <4>[ 156.701712] [4: kswapd0: 1209] unevictable:48292 di= rty:538 writeback:38 unstable:0 > >>>> <4>[ 156.701712] [4: kswapd0: 1209] slab_reclaimable:151= 31 slab_unreclaimable:47762 > >>>> <4>[ 156.701712] [4: kswapd0: 1209] mapped:274654 shmem:= 2824 pagetables:25088 bounce:0 > >>>> <4>[ 156.701712] [4: kswapd0: 1209] free:2489 free_pcp:4= 44 free_cma:3 > >>>> <4>[ 156.701728] [4: kswapd0: 1209] Node 0 active_anon:35= 4760kB inactive_anon:354520kB active_file:396692kB inactive_file:677220kB= unevictable:193168kB isolated(anon):0kB isolated(file):128kB mapped:1098= 616kB dirty:2152kB writeback:152kB shmem:11296kB writeback_tmp:0kB unstab= le:0kB all_unreclaimable? no > >>>> <4>[ 156.701738] [4: kswapd0: 1209] Normal free:9956kB mi= n:7428kB low:93440kB high:97032kB active_anon:355176kB inactive_anon:3545= 80kB active_file:396196kB inactive_file:677284kB unevictable:193168kB wri= tepending:2304kB present:4081664kB managed:3593324kB mlocked:193168kB ker= nel_stack:55008kB pagetables:100352kB bounce:0kB free_pcp:1776kB local_pc= p:656kB free_cma:12kB > >>>> <4>[ 156.701741] [4: kswapd0: 1209] lowmem_reserve[]: 0 0 > >>>> <4>[ 156.701747] [4: kswapd0: 1209] Normal: 196*4kB (H) 1= 41*8kB (H) 109*16kB (H) 63*32kB (H) 20*64kB (H) 8*128kB (H) 2*256kB (H) 1= *512kB (H) 0*1024kB 0*2048kB 0*4096kB =3D 9000kB > >>>> > >>>> Signed-off-by: Jaewon Kim > >>>> Reported-by: Yong-Taek Lee > >>>> --- > >>>> mm/page_alloc.c | 13 +++++++++++-- > >>>> 1 file changed, 11 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >>>> index 13cc653122b7..00869378d387 100644 > >>>> --- a/mm/page_alloc.c > >>>> +++ b/mm/page_alloc.c > >>>> @@ -3553,6 +3553,11 @@ static inline bool zone_watermark_fast(stru= ct zone *z, unsigned int order, > >>>> { > >>>> long free_pages =3D zone_page_state(z, NR_FREE_PAGES); > >>>> long cma_pages =3D 0; > >>>> + long highatomic =3D 0; > >>>> + const bool alloc_harder =3D (alloc_flags & (ALLOC_HARDER|ALLOC_O= OM)); > >>>> + > >>>> + if (likely(!alloc_harder)) > >>>> + highatomic =3D z->nr_reserved_highatomic; > >>>> =20 > >>>> #ifdef CONFIG_CMA > >>>> /* If allocation can't use CMA areas don't use free CMA pages */ > >>>> @@ -3567,8 +3572,12 @@ static inline bool zone_watermark_fast(stru= ct zone *z, unsigned int order, > >>>> * the caller is !atomic then it'll uselessly search the free > >>>> * list. That corner case is then slower but it is harmless. > >>>> */ > >>>> - if (!order && (free_pages - cma_pages) > mark + z->lowmem_reserv= e[classzone_idx]) > >>>> - return true; > >>>> + if (!order) { > >>>> + long fast_free =3D free_pages - cma_pages - highatomic; > >>> With your change, it seems we share most code for getting free_page= s=20 > >>> between zone_watermark_fast and __zone_watermark_ok. Only differenc= e > >>> between them is min calculation. If so, can we share most code betw= een > >>> them via introducing like __zone_watermark_free static inline funct= ion? > >>> So, we didn't miss one place in future if we change something. > >>> > >> Hello thank you for your comment. > >> > >> I tried to share some code. > >> Because __zone_watermark_ok gets free pages as argument, > >> I just could make a function calculating unusable free. > >> > >> static inline long __zone_watermark_unusable_free(struct zone *z, > >> unsigned int all= oc_flags) > >> > >> on zone_watermark_fast > >> free_pages -=3D __zone_watermark_unusable_free(z, alloc_flags); > >> > >> on __zone_watermark_ok > >> free_pages -=3D __zone_watermark_unusable_free(z, alloc_flags); > > Don't you need order argument? > Yes I actually I also took a consideration for it. >=20 > If I keep existing logic of zone_watermark_fast, > following code in __zone_watermark_ok is not needed for __zone_watermar= k_unusable_free > free_pages -=3D (1 << order) - 1; >=20 > But if __zone_watermark_unusable_free should return > all unusable free, the order size should be included. >=20 > Seems not critical but I want to hear opensource opinion. I don't think it could make measurable regression and if we want to factor it out, it would be better to be self-contained. To me, it looks weird if we need one more logic to consider *order* after __zone_watermark_unusable_free. IMHO, if we couldn't make it neat, the open-code like as-is would be better. Since I am not strong against of either way, up to you. Thanks.