From: Mike Kravetz <mike.kravetz@oracle.com>
To: Joonsoo Kim <js1304@gmail.com>, Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-team@lge.com, Vlastimil Babka <vbabka@suse.cz>,
Christoph Hellwig <hch@infradead.org>,
Roman Gushchin <guro@fb.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v3 4/8] mm/hugetlb: make hugetlb migration callback CMA aware
Date: Tue, 30 Jun 2020 09:37:16 -0700 [thread overview]
Message-ID: <eebb68b9-99f8-3f55-9b35-59fe8ddd1b75@oracle.com> (raw)
In-Reply-To: <CAAmzW4MFw_Xd_3rV8OVL_8jXfhUWT2v69xEFHaVLY4NKZPhD1A@mail.gmail.com>
On 6/30/20 12:22 AM, Joonsoo Kim wrote:
> 2020년 6월 30일 (화) 오후 3:42, Michal Hocko <mhocko@kernel.org>님이 작성:
>>
>> On Tue 30-06-20 15:30:04, Joonsoo Kim wrote:
>>> 2020년 6월 29일 (월) 오후 4:55, Michal Hocko <mhocko@kernel.org>님이 작성:
>> [...]
>>>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>>>> index 57ece74e3aae..c1595b1d36f3 100644
>>>> --- a/mm/hugetlb.c
>>>> +++ b/mm/hugetlb.c
>>>> @@ -1092,10 +1092,14 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask,
>>>> /* Movability of hugepages depends on migration support. */
>>>> static inline gfp_t htlb_alloc_mask(struct hstate *h)
>>>> {
>>>> + gfp_t gfp;
>>>> +
>>>> if (hugepage_movable_supported(h))
>>>> - return GFP_HIGHUSER_MOVABLE;
>>>> + gfp = GFP_HIGHUSER_MOVABLE;
>>>> else
>>>> - return GFP_HIGHUSER;
>>>> + gfp = GFP_HIGHUSER;
>>>> +
>>>> + return current_gfp_context(gfp);
>>>> }
>>>>
>>>> static struct page *dequeue_huge_page_vma(struct hstate *h,
>>>>
>>>> If we even fix this general issue for other allocations and allow a
>>>> better CMA exclusion then it would be implemented consistently for
>>>> everybody.
>>>
>>> Yes, I have reviewed the memalloc_nocma_{} APIs and found the better way
>>> for CMA exclusion. I will do it after this patch is finished.
>>>
>>>> Does this make more sense to you are we still not on the same page wrt
>>>> to the actual problem?
>>>
>>> Yes, but we have different opinions about it. As said above, I will make
>>> a patch for better CMA exclusion after this patchset. It will make
>>> code consistent.
>>> I'd really appreciate it if you wait until then.
>>
>> As I've said I would _prefer_ simplicity over "correctness" if it is only
>> partial and hard to reason about from the userspace experience but this
>> is not something I would _insist_ on. If Mike as a maintainer of the
>> code is ok with that then I will not stand in the way.
>
> Okay.
I was OK with Joonsoo's original patch which is why I Ack'ed it. However,
my sense of simplicity and style may not be the norm as I have spent too
much time with the hugetlbfs code. :) That is why I did not chime in and
let Michal and Joonsoo discuss. I can see both sides of the issue. For
now, I am OK to go with Joonsoo's patch as long as the issue below is
considered in the the next patchset.
--
Mike Kravetz
>> But please note that a missing current_gfp_context inside
>> htlb_alloc_mask is a subtle bug. I do not think it matters right now but
>> with a growing use of scoped apis this might actually hit some day so I
>> believe we want to have it in place.
>
> Okay. I will keep in mind and consider it when fixing CMA exclusion on the
> other patchset.
>
> Thanks.
next prev parent reply other threads:[~2020-06-30 16:37 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 6:13 [PATCH v3 0/8] clean-up the migration target allocation functions js1304
2020-06-23 6:13 ` [PATCH v3 1/8] mm/page_isolation: prefer the node of the source page js1304
2020-06-23 6:13 ` [PATCH v3 2/8] mm/migrate: move migration helper from .h to .c js1304
2020-06-23 6:13 ` [PATCH v3 3/8] mm/hugetlb: unify migration callbacks js1304
2020-06-24 21:18 ` Mike Kravetz
2020-06-25 11:26 ` Michal Hocko
2020-06-26 4:02 ` Joonsoo Kim
2020-07-02 16:13 ` Vlastimil Babka
2020-07-03 0:55 ` Joonsoo Kim
2020-06-23 6:13 ` [PATCH v3 4/8] mm/hugetlb: make hugetlb migration callback CMA aware js1304
2020-06-25 11:54 ` Michal Hocko
2020-06-26 4:49 ` Joonsoo Kim
2020-06-26 7:23 ` Michal Hocko
2020-06-29 6:27 ` Joonsoo Kim
2020-06-29 7:55 ` Michal Hocko
2020-06-30 6:30 ` Joonsoo Kim
2020-06-30 6:42 ` Michal Hocko
2020-06-30 7:22 ` Joonsoo Kim
2020-06-30 16:37 ` Mike Kravetz [this message]
2020-06-23 6:13 ` [PATCH v3 5/8] mm/migrate: make a standard migration target allocation function js1304
2020-06-25 12:05 ` Michal Hocko
2020-06-26 5:02 ` Joonsoo Kim
2020-06-26 7:33 ` Michal Hocko
2020-06-29 6:41 ` Joonsoo Kim
2020-06-29 8:03 ` Michal Hocko
2020-06-30 7:19 ` Joonsoo Kim
2020-07-03 15:25 ` Vlastimil Babka
2020-06-23 6:13 ` [PATCH v3 6/8] mm/gup: use a standard migration target allocation callback js1304
2020-06-25 12:08 ` Michal Hocko
2020-06-26 5:03 ` Joonsoo Kim
2020-07-03 15:56 ` Vlastimil Babka
2020-07-06 8:34 ` Joonsoo Kim
2020-06-23 6:13 ` [PATCH v3 7/8] mm/mempolicy: " js1304
2020-06-25 12:09 ` Michal Hocko
2020-07-03 15:59 ` Vlastimil Babka
2020-07-08 1:20 ` Qian Cai
2020-07-08 6:45 ` Michal Hocko
2020-10-08 3:21 ` Hugh Dickins
2020-10-08 17:29 ` Mike Kravetz
2020-10-09 5:50 ` Hugh Dickins
2020-10-09 17:42 ` Mike Kravetz
2020-10-09 22:23 ` Hugh Dickins
2020-10-10 0:25 ` Mike Kravetz
2020-06-23 6:13 ` [PATCH v3 8/8] mm/page_alloc: remove a wrapper for alloc_migration_target() js1304
2020-06-25 12:10 ` Michal Hocko
2020-07-03 16:18 ` Vlastimil Babka
2020-07-06 8:44 ` Joonsoo Kim
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