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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 97C0DC10F27 for ; Wed, 11 Mar 2020 11:43:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 54A3B21655 for ; Wed, 11 Mar 2020 11:43:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 54A3B21655 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EDA556B0003; Wed, 11 Mar 2020 07:43:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E8C0E6B0006; Wed, 11 Mar 2020 07:43:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA0C76B0007; Wed, 11 Mar 2020 07:43:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0228.hostedemail.com [216.40.44.228]) by kanga.kvack.org (Postfix) with ESMTP id BEB6C6B0003 for ; Wed, 11 Mar 2020 07:43:08 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 7A8AD181AEF1A for ; Wed, 11 Mar 2020 11:43:08 +0000 (UTC) X-FDA: 76582895256.14.top32_8fb9b8e081817 X-HE-Tag: top32_8fb9b8e081817 X-Filterd-Recvd-Size: 16595 Received: from relay.sw.ru (relay.sw.ru [185.231.240.75]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Wed, 11 Mar 2020 11:43:07 +0000 (UTC) Received: from dhcp-172-16-24-104.sw.ru ([172.16.24.104]) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1jBzl2-0006Eu-OS; Wed, 11 Mar 2020 14:42:40 +0300 Subject: Re: [PATCH v2 1/1] mm: fix interrupt disabled long time inside deferred_init_memmap() To: Shile Zhang , Andrew Morton , Pavel Tatashin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Michal Hocko References: <20200303161551.132263-1-shile.zhang@linux.alibaba.com> <20200303161551.132263-2-shile.zhang@linux.alibaba.com> <386d7d5f-a57d-f5b1-acee-131ce23d35ec@linux.alibaba.com> <2d4defb7-8816-3447-3d65-f5d80067a9fd@virtuozzo.com> <1856c956-858f-82d4-f3b3-05b2d0e5641c@linux.alibaba.com> From: Kirill Tkhai Message-ID: <094fcf02-37bd-c9b9-7156-77b9b34955e0@virtuozzo.com> Date: Wed, 11 Mar 2020 14:42:40 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <1856c956-858f-82d4-f3b3-05b2d0e5641c@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US 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 11.03.2020 04:44, Shile Zhang wrote: > Hi Kirill, >=20 > Sorry for late to reply! > I'm not fully understood the whole thing about deferred page init, so I > just force on the jiffies update issue itself. >=20 > Maybe I'm in wrong path, it seems make no sense that deferred page init= in 1 CPU system, > it cannot be initialize memory parallel. Yes, it can't be initialized in parallel. But scheduler interprets deferr= ed thread as a separate task, so CPU time will be shared between that thread and the rest of task= s. This still should make boot faster. > It might be better to disable deferred page init in 'deferred_init' in = case of 1 CPU > (or only one memory node). >=20 > In other word, seems the better way to solve this issue is do not bind = 'pgdatinit' thread > on boot CPU. >=20 > I also refactor the patch based on your comment, please help to check, = thanks! >=20 >=20 > On 2020/3/4 18:47, Kirill Tkhai wrote: >> On 04.03.2020 05:34, Shile Zhang wrote: >>> Hi Kirill, >>> >>> Thanks for your quickly reply! >>> >>> On 2020/3/4 00:52, Kirill Tkhai wrote: >>>> On 03.03.2020 19:15, Shile Zhang wrote: >>>>> When 'CONFIG_DEFERRED_STRUCT_PAGE_INIT' is set, 'pgdatinit' kthread= will >>>>> initialise the deferred pages with local interrupts disabled. It is >>>>> introduced by commit 3a2d7fa8a3d5 ("mm: disable interrupts while >>>>> initializing deferred pages"). >>>>> >>>>> The local interrupt will be disabled long time inside >>>>> deferred_init_memmap(), depends on memory size. >>>>> On machine with NCPUS <=3D 2, the 'pgdatinit' kthread could be pine= d on >>>>> boot CPU, then the tick timer will stuck long time, which caused th= e >>>>> system wall time inaccuracy. >>>>> >>>>> For example, the dmesg shown that: >>>>> >>>>> =C2=A0=C2=A0=C2=A0 [=C2=A0=C2=A0=C2=A0 0.197975] node 0 initialised= , 32170688 pages in 1ms >>>>> >>>>> Obviously, 1ms is unreasonable. >>>>> Now, fix it by restore in the pending interrupts inside the while l= oop. >>>>> The reasonable demsg shown likes: >>>>> >>>>> [=C2=A0=C2=A0=C2=A0 1.069306] node 0 initialised, 32203456 pages in= 894ms >>>> The way I understand the original problem, that Pavel fixed: >>>> >>>> we need disable irqs in deferred_init_memmap() since this function m= ay be called >>>> in parallel with deferred_grow_zone() called from interrupt handler.= So, Pavel >>>> added lock to fix the race. >>>> >>>> In case of we temporary unlock the lock, interrupt still be possible= , >>>> so my previous proposition returns the problem back. >>>> >>>> Now thought again, I think we have to just add: >>>> >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0pgdat_resize_unlock(); >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0pgdat_resize_lock(); >>>> >>>> instead of releasing interrupts, since in case of we just release th= em with lock held, >>>> a call of interrupt->deferred_grow_zone() bring us to a deadlock. >>>> >>>> So, unlock the lock is must. >>> Yes, you're right! I missed this point. >>> Thanks for your comment! >>> >>>>> Signed-off-by: Shile Zhang >>>>> --- >>>>> =C2=A0=C2=A0 mm/page_alloc.c | 6 +++++- >>>>> =C2=A0=C2=A0 1 file changed, 5 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>>>> index 3c4eb750a199..d3f337f2e089 100644 >>>>> --- a/mm/page_alloc.c >>>>> +++ b/mm/page_alloc.c >>>>> @@ -1809,8 +1809,12 @@ static int __init deferred_init_memmap(void = *data) >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * that we can avoid intr= oducing any issues with the buddy >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * allocator. >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >>>>> -=C2=A0=C2=A0=C2=A0 while (spfn < epfn) >>>>> +=C2=A0=C2=A0=C2=A0 while (spfn < epfn) { >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nr_pag= es +=3D deferred_init_maxorder(&i, zone, &spfn, &epfn); >>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* let in any pending i= nterrupts */ >>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 local_irq_restore(flags= ); >>>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 local_irq_save(flags); >>>>> +=C2=A0=C2=A0=C2=A0 } >>>>> =C2=A0=C2=A0 zone_empty: >>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize_unlock(pgdat, &fl= ags); >>>> I think we need here something like below (untested): >>>> >>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>>> index 79e950d76ffc..323afa9a4db5 100644 >>>> --- a/mm/page_alloc.c >>>> +++ b/mm/page_alloc.c >>>> @@ -1828,7 +1828,7 @@ static int __init deferred_init_memmap(void *d= ata) >>>> =C2=A0=C2=A0 { >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pg_data_t *pgdat =3D data; >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 const struct cpumask *cpumask =3D= cpumask_of_node(pgdat->node_id); >>>> -=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn =3D 0, nr_pages =3D= 0; >>>> +=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn =3D 0, nr_pages =3D= 0, prev_nr_pages =3D 0; >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long first_init_pfn, f= lags; >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long start =3D jiffies= ; >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct zone *zone; >>>> @@ -1869,8 +1869,18 @@ static int __init deferred_init_memmap(void *= data) >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * that we can avoid intro= ducing any issues with the buddy >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * allocator. >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >>>> -=C2=A0=C2=A0=C2=A0 while (spfn < epfn) >>>> +=C2=A0=C2=A0=C2=A0 while (spfn < epfn) { >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nr_page= s +=3D deferred_init_maxorder(&i, zone, &spfn, &epfn); >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * Release interrup= ts every 1Gb to give a possibility >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * a timer to advan= ce jiffies. >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (nr_pages - prev_nr_p= ages > (1UL << (30 - PAGE_SHIFT))) { >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = prev_nr_pages =3D nr_pages; >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = pgdat_resize_unlock(pgdat, &flags); >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = pgdat_resize_lock(pgdat, &flags); >>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >>>> +=C2=A0=C2=A0=C2=A0 } >>>> =C2=A0=C2=A0 zone_empty: >>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize_unlock(pgdat, &fla= gs); >>>> =C2=A0 (I believe the comment may be improved more). >>> Yeah, your patch is better! >>> I test your code and it works! >>> But it seems that 1G is still hold the interrupts too long, about 40m= s in my env >>> with Intel(R) Xeon(R) 2.5GHz). I tried other size, it is OK to use 10= 24 pages (4MB), >>> which suggested by Andrew's before. >>> >>> Could you please help to review it again? >>> >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>> index 3c4eb750a199..5def66d3ffcd 100644 >>> --- a/mm/page_alloc.c >>> +++ b/mm/page_alloc.c >>> @@ -1768,7 +1768,7 @@ static int __init deferred_init_memmap(void *da= ta) >>> =C2=A0=C2=A0{ >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pg_data_t *pgdat =3D= data; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 const struct cpumask= *cpumask =3D cpumask_of_node(pgdat->node_id); >>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn = =3D 0, nr_pages =3D 0; >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn = =3D 0, nr_pages =3D 0, prev_nr_pages =3D 0; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long first_= init_pfn, flags; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long start = =3D jiffies; >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct zone *zone; >>> @@ -1809,8 +1809,17 @@ static int __init deferred_init_memmap(void *d= ata) >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * that we can = avoid introducing any issues with the buddy >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * allocator. >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 while (spfn < epfn) >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 while (spfn < epfn) { >>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 nr_pages +=3D deferred_init_maxorder(&i, zone= , &spfn, &epfn); >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 /* >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 * Restore pending interrupts every 1024 pages to gi= ve >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 * the chance tick timer to advance jiffies. >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 */ >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 if (nr_pages - prev_nr_pages > 1024) { >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_res= ize_unlock(&flags); >>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_res= ize_lock(&flags); >> Here is problem: prev_nr_pages must be updated. >> >> Anyway, releasing every 4M looks wrong for me, since you removes the f= ix that Pavel introduced. >> He protected against big allocations made from interrupt content. But = in case of we unlock >> the lock after 4Mb, only 4Mb will be available for allocations from in= terrupts. pgdat->first_deferred_pfn >> is updated at the start of function, so interrupt allocations won't be= able to initialize >> mode for themselve. >=20 > Yes, you're right. I missed this point since I'm not fully understood t= he code before. > Thanks for your advice! >> In case of you want unlock interrupts very often, you should make some= creativity with first_deferred_pfn. >> We should update it sequentially. Something like below (untested): >=20 > I got your point now, thanks! >> --- >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 79e950d76ffc..be09d158baeb 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -1828,7 +1828,7 @@ static int __init deferred_init_memmap(void *dat= a) >> =C2=A0 { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pg_data_t *pgdat =3D data; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 const struct cpumask *cpumask =3D cpuma= sk_of_node(pgdat->node_id); >> -=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn =3D 0, nr_pages =3D= 0; >> +=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn =3D 0, nr_pages; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long first_init_pfn, flags; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long start =3D jiffies; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct zone *zone; >> @@ -1838,7 +1838,7 @@ static int __init deferred_init_memmap(void *dat= a) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Bind memory initialisation thread to= a local node if possible */ >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!cpumask_empty(cpumask)) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 set_cpus_allowe= d_ptr(current, cpumask); >> - >> +again: >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize_lock(pgdat, &flags); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 first_init_pfn =3D pgdat->first_deferre= d_pfn; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (first_init_pfn =3D=3D ULONG_MAX) { >> @@ -1850,7 +1850,6 @@ static int __init deferred_init_memmap(void *dat= a) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Sanity check boundaries */ >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 BUG_ON(pgdat->first_deferred_pfn < pgda= t->node_start_pfn); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 BUG_ON(pgdat->first_deferred_pfn > pgda= t_end_pfn(pgdat)); >> -=C2=A0=C2=A0=C2=A0 pgdat->first_deferred_pfn =3D ULONG_MAX; >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Only the highest zone is defe= rred so find it */ >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 for (zid =3D 0; zid < MAX_NR_ZONES; zid= ++) { >> @@ -1864,14 +1863,30 @@ static int __init deferred_init_memmap(void *d= ata) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 first_init_pfn)) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto zone_empty= ; >> =C2=A0 +=C2=A0=C2=A0=C2=A0 nr_pages =3D 0; >=20 > 'nr_pages' used to mark the total init pages before, so it cannot be ze= rolized each round. > seems we need one more to count the pages init each round. >=20 >> + >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * Initialize and free pages in MA= X_ORDER sized increments so >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * that we can avoid introducing a= ny issues with the buddy >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * allocator. >> +=C2=A0=C2=A0=C2=A0=C2=A0 * Final iteration marker is: spfn=3DULONG_MA= X and epfn=3D0. >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >> -=C2=A0=C2=A0=C2=A0 while (spfn < epfn) >> +=C2=A0=C2=A0=C2=A0 while (spfn < epfn) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nr_pages +=3D d= eferred_init_maxorder(&i, zone, &spfn, &epfn); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!epfn) >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 br= eak; >=20 > Seems 'epfn' never goes to 0 since it is "end page frame number", right= ? > So this is needless. >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat->first_deferred_pfn = =3D epfn; >=20 > I think first_deferred_pfn update wrong value here, it seems should be = the spfn, the start pfn right? >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * Restore pending in= terrupts every 128Mb to give >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * the chance tick ti= mer to advance jiffies. >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (nr_pages > (1UL << 27 = - PAGE_SHIFT)) { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pg= dat_resize_unlock(pgdat, &flags); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 go= to again; >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> +=C2=A0=C2=A0=C2=A0 } >> =C2=A0 zone_empty: >> +=C2=A0=C2=A0=C2=A0 pgdat->first_deferred_pfn =3D ULONG_MAX; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize_unlock(pgdat, &flags); >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Sanity check that the next zo= ne really is unpopulated */ >> >> > I update the patch based on your comment, it passed the test. > Could you please help to review it again? Thanks! The patch is OK for me. It may be sent into ml with an appropriate descri= ption. Feel free to not forget to add my: Co-developed-by: Kirill Tkhai > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 3c4eb750a199..841c902d4509 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1763,12 +1763,17 @@ deferred_init_maxorder(u64 *i, struct zone *zon= e, unsigned long *start_pfn, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return nr_pages; > =C2=A0} >=20 > +/* > + * Release the tick timer interrupts for every TICK_PAGE_COUNT pages. > + */ > +#define TICK_PAGE_COUNT=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 (32 = * 1024) > + > =C2=A0/* Initialise remaining memory on a node */ > =C2=A0static int __init deferred_init_memmap(void *data) > =C2=A0{ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pg_data_t *pgdat =3D data; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 const struct cpumask *cpumas= k =3D cpumask_of_node(pgdat->node_id); > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn =3D= 0, nr_pages =3D 0; > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long spfn =3D 0, epfn =3D= 0, nr_pages =3D 0, prev_nr_pages =3D 0; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long first_init_pfn= , flags; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 unsigned long start =3D jiff= ies; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct zone *zone; > @@ -1779,6 +1784,7 @@ static int __init deferred_init_memmap(void *data= ) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!cpumask_empty(cpumask)) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 set_cpus_allowed_ptr(current, cpumask); >=20 > +again: > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize_lock(pgdat, &fl= ags); > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 first_init_pfn =3D pgdat->fi= rst_deferred_pfn; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (first_init_pfn =3D=3D UL= ONG_MAX) { > @@ -1790,7 +1796,6 @@ static int __init deferred_init_memmap(void *data= ) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Sanity check boundaries *= / > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 BUG_ON(pgdat->first_deferred= _pfn < pgdat->node_start_pfn); > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 BUG_ON(pgdat->first_deferred= _pfn > pgdat_end_pfn(pgdat)); > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat->first_deferred_pfn =3D ULO= NG_MAX; >=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Only the highest zone is = deferred so find it */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 for (zid =3D 0; zid < MAX_NR= _ZONES; zid++) { > @@ -1809,9 +1814,23 @@ static int __init deferred_init_memmap(void *dat= a) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * that we can avoid in= troducing any issues with the buddy > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * allocator. > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 while (spfn < epfn) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 while (spfn < epfn) { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 nr_pages +=3D deferred_init_maxorder(&i, zone, &spfn, = &epfn); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 /* > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 * Release the interrupts for every TICK_PAGE_COUNT pag= es > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 * (128MB) to give the chance that tick timer to advanc= e > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 * the jiffies. > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 */ > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 if ((nr_pages - prev_nr_pages) > TICK_PAGE_COUNT) { > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 prev_nr_page= s =3D nr_pages; > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat->first= _deferred_pfn =3D spfn; > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize= _unlock(pgdat, &flags); > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 goto again; > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0 } > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } > + > =C2=A0zone_empty: > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat->first_deferred_pfn =3D ULO= NG_MAX; > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 pgdat_resize_unlock(pgdat, &= flags); >=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* Sanity check that the nex= t zone really is unpopulated */ >=20