From: Michal Hocko <mhocko@suse.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Li Xinhai <lixinhai.lxh@gmail.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
akpm <akpm@linux-foundation.org>,
"yang.shi" <yang.shi@linux.alibaba.com>,
n-horiguchi <n-horiguchi@ah.jp.nec.com>
Subject: Re: [PATCH 2/2] mm/mempolicy: Skip walking HUGETLB vma if MPOL_MF_STRICT is specified alone
Date: Thu, 16 Jan 2020 08:59:33 +0100 [thread overview]
Message-ID: <20200116075933.GN19428@dhcp22.suse.cz> (raw)
In-Reply-To: <c102d153-5093-94c9-7e6d-65fd6881831d@oracle.com>
On Wed 15-01-20 13:07:17, Mike Kravetz wrote:
[...]
> Summary
> =======
> It 'looks' like the statement "MPOL_MF_STRICT is ignored on huge page
> mappings." is left over from the original mbind implementation. When
> the huge page migration support was added, I can not be sure if ignoring
> MPOL_MF_STRICT for huge pages during the verify/isolation phase was
> intentional. It seems like it was as the return value from
> isolate_huge_page() is ignored.
THanks for the tedious work of studying the mess^Whistory.
>
> What should we do?
> ==================
> 1) Nothing more than optimizations by Li Xinhai. Behavior that could be
> seen as conflicting with man page has existed since v3.12 and I am
> not aware of any complaints.
> 2) In addition to optimizations by Li Xinhai, modify code to truly ignore
> MPOL_MF_STRICT for huge page mappings. This would be fairly easy to do
> after a failure of migrate_pages(). We could simply traverse the list
> of pages that were not migrated looking for any non-hugetlb page.
> 3) Remove the statement "MPOL_MF_STRICT is ignored on huge page mappings."
> and modify code accordingly.
>
> My suggestion would be for 1 or 2. Thoughts?
And why do we exactly need to do anything at all? There is an
inconsistency that has been there for years without anybody noticing.
NUMA API is a mess on its own and unfixable at this stage, there will
always be some corner cases. If there is no real workload hitting this
incosistency and suffering, I would rather not touch this at all.
Unless the change would clean up the code or make it more maintainable.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-01-16 7:59 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 9:16 [PATCH 1/2] mm/mempolicy: Checking hstate for hugetlbfs page in vma_migratable Li Xinhai
2020-01-14 9:16 ` [PATCH 2/2] mm/mempolicy: Skip walking HUGETLB vma if MPOL_MF_STRICT is specified alone Li Xinhai
2020-01-14 14:09 ` Li Xinhai
2020-01-14 18:27 ` Yang Shi
2020-01-15 1:07 ` Mike Kravetz
2020-01-15 1:24 ` Yang Shi
2020-01-15 4:28 ` Mike Kravetz
2020-01-15 5:23 ` Yang Shi
2020-01-15 7:36 ` Li Xinhai
2020-01-15 17:16 ` Yang Shi
2020-01-15 21:07 ` Mike Kravetz
2020-01-15 21:30 ` Yang Shi
2020-01-15 21:45 ` Mike Kravetz
2020-01-15 21:59 ` Yang Shi
2020-01-16 8:07 ` HORIGUCHI NAOYA(堀口 直也)
2020-01-16 15:32 ` Li Xinhai
2020-01-16 7:59 ` Michal Hocko [this message]
2020-01-16 19:22 ` Mike Kravetz
2020-01-17 2:32 ` Yang Shi
2020-01-17 2:38 ` Li Xinhai
2020-01-17 7:57 ` Michal Hocko
2020-01-17 12:05 ` Li Xinhai
2020-01-17 15:20 ` Michal Hocko
2020-01-17 15:46 ` Li Xinhai
2020-01-20 12:45 ` Michal Hocko
2020-01-21 14:15 ` Li Xinhai
2020-01-21 14:53 ` Michal Hocko
2020-01-22 13:55 ` Li Xinhai
2020-01-14 19:12 ` [PATCH 1/2] mm/mempolicy: Checking hstate for hugetlbfs page in vma_migratable Mike Kravetz
2020-01-15 1:25 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200116075933.GN19428@dhcp22.suse.cz \
--to=mhocko@suse.com \
--cc=akpm@linux-foundation.org \
--cc=linux-mm@kvack.org \
--cc=lixinhai.lxh@gmail.com \
--cc=mike.kravetz@oracle.com \
--cc=n-horiguchi@ah.jp.nec.com \
--cc=yang.shi@linux.alibaba.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).