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From: Vlastimil Babka <vbabka@suse.cz>
To: Mike Kravetz <mike.kravetz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	David Hildenbrand <david@redhat.com>,
	Michal Hocko <mhocko@suse.com>,
	Oscar Salvador <osalvador@suse.de>, Zi Yan <ziy@nvidia.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Naoya Horiguchi <naoya.horiguchi@linux.dev>,
	David Rientjes <rientjes@google.com>,
	Hillf Danton <hdanton@sina.com>
Subject: Re: [PATCH RESEND 0/8] hugetlb: add demote/split page functionality
Date: Fri, 27 Aug 2021 19:22:52 +0200	[thread overview]
Message-ID: <efcf6049-6110-d516-b21f-41bb8775f042@suse.cz> (raw)
In-Reply-To: <10d86c18-f0cf-395f-4209-17ac71b9fc03@oracle.com>

On 8/25/21 00:08, Mike Kravetz wrote:
> Add Vlastimil and Hillf,
> 
> Well, I set up a test environment on a larger system to get some
> numbers.  My 'load' on the system was filling the page cache with
> clean pages.  The thought is that these pages could easily be reclaimed.
> 
> When trying to get numbers I hit a hugetlb page allocation stall where
> __alloc_pages(__GFP_RETRY_MAYFAIL, order 9) would stall forever (or at
> least an hour).  It was very much like the symptoms addressed here:
> https://lore.kernel.org/linux-mm/20190806014744.15446-1-mike.kravetz@oracle.com/
> 
> This was on 5.14.0-rc6-next-20210820.
> 
> I'll do some more digging as this appears to be some dark corner case of
> reclaim and/or compaction.  The 'good news' is that I can reproduce
> this.

Interesting, let's see if that's some kind of new regression.

>> And the second problem would benefit from some words to help us
>> understand how much real-world hurt this causes, and how frequently.
>> And let's understand what the userspace workarounds look like, etc.
> 
> The stall above was from doing a simple 'free 1GB page' followed by
> 'allocate 512 MB pages' from userspace.

Is the allocation different in any way than the usual hugepage allocation
possible today?

> Getting out another version of this series will be delayed, as I think
> we need to address or understand this issue first.
> 


  reply	other threads:[~2021-08-27 17:23 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-16 22:49 Mike Kravetz
2021-08-16 22:49 ` [PATCH 1/8] hugetlb: add demote hugetlb page sysfs interfaces Mike Kravetz
2021-08-16 22:49 ` [PATCH 2/8] hugetlb: add HPageCma flag and code to free non-gigantic pages in CMA Mike Kravetz
2021-08-16 22:49 ` [PATCH 3/8] hugetlb: add demote bool to gigantic page routines Mike Kravetz
2021-08-16 22:49 ` [PATCH 4/8] hugetlb: add hugetlb demote page support Mike Kravetz
2021-08-16 22:49 ` [PATCH 5/8] hugetlb: document the demote sysfs interfaces Mike Kravetz
2021-08-16 23:28   ` Andrew Morton
2021-08-17  1:04     ` Mike Kravetz
2021-09-21 13:52   ` Aneesh Kumar K.V
2021-09-21 17:17     ` Mike Kravetz
2021-08-16 22:49 ` [PATCH 6/8] hugetlb: vmemmap optimizations when demoting hugetlb pages Mike Kravetz
2021-08-16 22:49 ` [PATCH 7/8] hugetlb: prepare destroy and prep routines for vmemmap optimized pages Mike Kravetz
2021-08-16 22:49 ` [PATCH 8/8] hugetlb: Optimized demote vmemmap optimizatized pages Mike Kravetz
2021-08-16 23:23 ` [PATCH RESEND 0/8] hugetlb: add demote/split page functionality Andrew Morton
2021-08-17  0:17   ` Mike Kravetz
2021-08-17  0:39     ` Andrew Morton
2021-08-17  0:58       ` Mike Kravetz
2021-08-16 23:27 ` Andrew Morton
2021-08-17  0:46   ` Mike Kravetz
2021-08-17  1:46     ` Andrew Morton
2021-08-17  7:30       ` David Hildenbrand
2021-08-17 16:19         ` Mike Kravetz
2021-08-17 18:49           ` David Hildenbrand
2021-08-24 22:08       ` Mike Kravetz
2021-08-27 17:22         ` Vlastimil Babka [this message]
2021-08-27 23:04           ` Mike Kravetz
2021-08-30 10:11             ` Vlastimil Babka
2021-09-02 18:17               ` Mike Kravetz
2021-09-06 14:40                 ` Vlastimil Babka
     [not found]                 ` <20210907085001.3773-1-hdanton@sina.com>
2021-09-08 21:00                   ` Mike Kravetz
2021-09-09 11:54                     ` Michal Hocko
2021-09-09 13:45                       ` Vlastimil Babka
2021-09-09 21:31                         ` Mike Kravetz
2021-09-10  8:20                         ` Michal Hocko
2021-09-11  0:11                           ` Mike Kravetz
2021-09-13 15:50                             ` Michal Hocko
2021-09-15 16:57                               ` Mike Kravetz
2021-09-17 20:44                                 ` Mike Kravetz

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