Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.32 as permitted sender) client-ip=23.128.96.32;
Message-ID: <ca6093e6-fc85-9ce8-71a1-77d8996c9fd6@quicinc.com>
Date:   Wed, 1 Nov 2023 12:23:24 +0530
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.13.0
Subject: Re: [PATCH] mm: page_alloc: unreserve highatomic page blocks before
 oom
Content-Language: en-US
To:     Pavan Kondeti <quic_pkondeti@quicinc.com>
CC:     Michal Hocko <mhocko@suse.com>, <akpm@linux-foundation.org>,
        <mgorman@techsingularity.net>, <david@redhat.com>,
        <vbabka@suse.cz>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
References: <1698669590-3193-1-git-send-email-quic_charante@quicinc.com>
 <gtya2g2pdbsonelny6vpfwj5vsxdrzhi6wzkpcrke33mr3q2hf@j4ramnjmfx52>
 <2a0d2dd8-562c-fec7-e3ac-0bd955643e16@quicinc.com>
 <37c58833-1953-42c3-98c6-ee0ac75508ce@quicinc.com>
From:   Charan Teja Kalla <quic_charante@quicinc.com>
In-Reply-To: <37c58833-1953-42c3-98c6-ee0ac75508ce@quicinc.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 11/1/2023 12:16 PM, Pavan Kondeti wrote:
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 2a2536d..41441ced 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -1886,7 +1886,9 @@ static void reserve_highatomic_pageblock(struct
>> page *page, struct zone *zone)
>>          * Limit the number reserved to 1 pageblock or roughly 1% of a zone.
>>          * Check is race-prone but harmless.
>>          */
>> -       max_managed = (zone_managed_pages(zone) / 100) + pageblock_nr_pages;
>> +       max_managed = max_t(unsigned long,
>> +                       ALIGN(zone_managed_pages(zone) / 100,
>> pageblock_nr_pages),
>> +                       pageblock_nr_pages);
>>         if (zone->nr_reserved_highatomic >= max_managed)
>>                 return;
>>
> ALIGN() rounds up the value, so max_t() is not needed here. If you had
> used ALIGN_DOWN() then max_t() can be used to keep atleast
> pageblock_nr_pages pages.
> 
Yeah, just ALIGN() enough here.
> 
> Also, add below Fixes tag if it makes sense.
> 
> Fixes: 04c8716f7b00 ("mm: try to exhaust highatomic reserve before the OOM")
I should be adding this.