From: Oscar Salvador <osalvador@suse.de>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Michal Hocko <mhocko@kernel.org>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Muchun Song <songmuchun@bytedance.com>,
David Hildenbrand <david@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 2/5] hugetlb: convert page_huge_active() HPageMigratable flag
Date: Thu, 21 Jan 2021 09:18:16 +0100 [thread overview]
Message-ID: <20210121081812.GA9553@linux> (raw)
In-Reply-To: <0ef72fcf-7fd6-02f6-6fb5-69a2c5bcf7a4@oracle.com>
On Wed, Jan 20, 2021 at 01:48:05PM -0800, Mike Kravetz wrote:
> >> This comment addresses both this patch and the next one.
> >>
> >> Instead of putting the SetHPageMigratable flag spread over the
> >> allocation paths, would it make more sense to place it in
> >> alloc_huge_page before returning the page?
> >> Then we could opencode SetHPageMigratableIfSupported right there.
> >
> > and in putback_active_hugepage.
>
>
> Hi Oscar,
>
> In Muchun's series of hugetlb bug fixes, Michal asked the same question.
>
> https://lore.kernel.org/linux-mm/7e69a55c-d501-6b42-8225-a677f09fb829@oracle.com/
>
> The 'short answer' is that the this would allow a page to be migrated
> after allocation but before the page fault code adds it to the page
> cache or page tables. This actually caused bugs in the past.
Oh, I see. I jumped late into that patchset so I missed some early messages.
Thanks for explaining this again.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-01-21 8:18 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 1:30 [PATCH v2 0/5] create hugetlb flags to consolidate state Mike Kravetz
2021-01-20 1:30 ` [PATCH v2 1/5] hugetlb: use page.private for hugetlb specific page flags Mike Kravetz
2021-01-20 8:10 ` Miaohe Lin
2021-01-20 8:43 ` kernel test robot
2021-01-20 8:43 ` kernel test robot
2021-01-20 9:30 ` Oscar Salvador
2021-01-20 18:12 ` Mike Kravetz
2021-01-20 1:30 ` [PATCH v2 2/5] hugetlb: convert page_huge_active() HPageMigratable flag Mike Kravetz
2021-01-20 9:59 ` Oscar Salvador
2021-01-20 10:00 ` Oscar Salvador
2021-01-20 21:48 ` Mike Kravetz
2021-01-21 8:18 ` Oscar Salvador [this message]
2021-01-21 8:27 ` Oscar Salvador
2021-01-21 12:01 ` [External] " Muchun Song
2021-01-22 6:53 ` Miaohe Lin
2021-01-22 23:12 ` Mike Kravetz
2021-02-03 7:42 ` [External] " Muchun Song
2021-02-04 0:44 ` Mike Kravetz
2021-01-20 1:30 ` [PATCH v2 3/5] hugetlb: only set HPageMigratable for migratable hstates Mike Kravetz
2021-01-20 1:30 ` [PATCH v2 4/5] hugetlb: convert PageHugeTemporary() to HPageTemporary flag Mike Kravetz
2021-01-20 10:09 ` Oscar Salvador
2021-01-20 18:14 ` Mike Kravetz
2021-01-20 1:30 ` [PATCH v2 5/5] hugetlb: convert PageHugeFreed to HPageFreed flag Mike Kravetz
2021-01-20 10:10 ` Oscar Salvador
2021-01-20 10:44 ` [External] " Muchun Song
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