Re: [PATCH v6 4/6] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY

From: Mike Kravetz <mike.kravetz@oracle.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Feng Tang <feng.tang@intel.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	David Rientjes <rientjes@google.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Ben Widawsky <ben.widawsky@intel.com>,
	linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	Andrea Arcangeli <aarcange@redhat.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Randy Dunlap <rdunlap@infradead.org>,
	Vlastimil Babka <vbabka@suse.cz>, Andi Kleen <ak@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	ying.huang@intel.com
Subject: Re: [PATCH v6 4/6] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
Date: Thu, 22 Jul 2021 09:21:00 -0700	[thread overview]
Message-ID: <1bf315a3-5953-93ac-7bab-ff1328ee46e1@oracle.com> (raw)
In-Reply-To: <YPk9hTQ5KQCv7KFw@dhcp22.suse.cz>

On 7/22/21 2:42 AM, Michal Hocko wrote:
> On Wed 21-07-21 13:49:15, Mike Kravetz wrote:
>> On 7/12/21 1:09 AM, Feng Tang wrote:
> [...]
>>> +#ifdef CONFIG_NUMA
>>> +	if (mpol->mode == MPOL_PREFERRED_MANY) {
>>> +		gfp_t gfp = (gfp_mask | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM;
>>
>> I believe __GFP_NOWARN will be added later in alloc_buddy_huge_page, so
>> no need to add here?
> 
> The mask is manipulated here anyway and the __GFP_NOWARN is really
> telling that there is no need to report the failure for _this_
> allocation request. alloc_surplus_huge_page might alter that in whatever
> way in the future. So I would keep NOWARN here for the code clarity
> rather than rely on some implicit assumption down the path.

Makes sense.  Better to leave the __GFP_NOWARN here for clarity.

-- 
Mike Kravetz