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From: David Hildenbrand <david@redhat.com>
To: Zach O'Keefe <zokeefe@google.com>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	David Rientjes <rientjes@google.com>,
	Michal Hocko <mhocko@suse.com>,
	Pasha Tatashin <pasha.tatashin@soleen.com>,
	SeongJae Park <sj@kernel.org>, Song Liu <songliubraving@fb.com>,
	Vlastimil Babka <vbabka@suse.cz>, Zi Yan <ziy@nvidia.com>,
	linux-mm@kvack.org
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Chris Kennelly <ckennelly@google.com>,
	Chris Zankel <chris@zankel.net>, Helge Deller <deller@gmx.de>,
	Hugh Dickins <hughd@google.com>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Jens Axboe <axboe@kernel.dk>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Matthew Wilcox <willy@infradead.org>,
	Matt Turner <mattst88@gmail.com>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Minchan Kim <minchan@kernel.org>,
	Patrick Xia <patrickx@google.com>,
	Pavel Begunkov <asml.silence@gmail.com>,
	Peter Xu <peterx@redhat.com>, Richard Henderson <rth@twiddle.net>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Yang Shi <shy828301@gmail.com>
Subject: Re: [RFC PATCH 07/14] mm/khugepaged: add vm_flags_ignore to hugepage_vma_revalidate_pmd_count()
Date: Thu, 10 Mar 2022 16:56:31 +0100	[thread overview]
Message-ID: <30571216-5a6a-7a11-3b2c-77d914025f6d@redhat.com> (raw)
In-Reply-To: <20220308213417.1407042-8-zokeefe@google.com>

On 08.03.22 22:34, Zach O'Keefe wrote:
> In madvise collapse context, we optionally want to be able to ignore
> advice from MADV_NOHUGEPAGE-marked regions.
> 
> Add a vm_flags_ignore argument to hugepage_vma_revalidate_pmd_count()
> which can be used to ignore vm flags used when considering thp
> eligibility.

arch/s390/mm/gmap.c:thp_split_mm() sets VM_NOHUGEPAGE to make sure there
are *really* no thp. Being able to bypass that would break KVM horribly.

Ignoring MADV_NOHUGEPAGE/VM_NOHUGEPAGE feels like the wrong way to go.


What about a prctl instead, to disable any khugepagd activity and just
let that process control it manually?

-- 
Thanks,

David / dhildenb



  parent reply	other threads:[~2022-03-10 15:56 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-08 21:34 [RFC PATCH 00/14] mm: userspace hugepage collapse Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 01/14] mm/rmap: add mm_find_pmd_raw helper Zach O'Keefe
2022-03-09 22:48   ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 02/14] mm/khugepaged: add struct collapse_control Zach O'Keefe
2022-03-09 22:53   ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 03/14] mm/khugepaged: add __do_collapse_huge_page() helper Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 04/14] mm/khugepaged: separate khugepaged_scan_pmd() scan and collapse Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 05/14] mm/khugepaged: add mmap_assert_locked() checks to scan_pmd() Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 06/14] mm/khugepaged: add hugepage_vma_revalidate_pmd_count() Zach O'Keefe
2022-03-09 23:15   ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 07/14] mm/khugepaged: add vm_flags_ignore to hugepage_vma_revalidate_pmd_count() Zach O'Keefe
2022-03-09 23:17   ` Yang Shi
2022-03-10  0:00     ` Zach O'Keefe
2022-03-10  0:41       ` Yang Shi
2022-03-10  1:09         ` Zach O'Keefe
2022-03-10  2:16           ` Yang Shi
2022-03-10 15:50             ` Zach O'Keefe
2022-03-10 18:17               ` Yang Shi
2022-03-10 18:46                 ` David Rientjes
2022-03-10 18:58                   ` Zach O'Keefe
2022-03-10 19:54                   ` Yang Shi
2022-03-10 20:24                     ` Zach O'Keefe
2022-03-10 18:53                 ` Zach O'Keefe
2022-03-10 15:56   ` David Hildenbrand [this message]
2022-03-10 18:39     ` Zach O'Keefe
2022-03-10 18:54     ` David Rientjes
2022-03-21 14:27       ` Michal Hocko
2022-03-08 21:34 ` [RFC PATCH 08/14] mm/thp: add madv_thp_vm_flags to __transparent_hugepage_enabled() Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 09/14] mm/khugepaged: record SCAN_PAGE_COMPOUND when scan_pmd() finds THP Zach O'Keefe
2022-03-09 23:40   ` Yang Shi
2022-03-10  0:46     ` Zach O'Keefe
2022-03-10  2:05       ` Yang Shi
2022-03-10  8:37         ` Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 10/14] mm/khugepaged: rename khugepaged-specific/not functions Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 11/14] mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse Zach O'Keefe
2022-03-09 23:43   ` Yang Shi
2022-03-10  1:11     ` Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 12/14] mm/madvise: introduce batched madvise(MADV_COLLPASE) collapse Zach O'Keefe
2022-03-10  0:06   ` Yang Shi
2022-03-10 19:26     ` David Rientjes
2022-03-10 20:16       ` Matthew Wilcox
2022-03-11  0:06         ` Zach O'Keefe
2022-03-25 16:51           ` Zach O'Keefe
2022-03-25 19:54             ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 13/14] mm/madvise: add __madvise_collapse_*_batch() actions Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 14/14] mm/madvise: add process_madvise(MADV_COLLAPSE) Zach O'Keefe
2022-03-21 14:32 ` [RFC PATCH 00/14] mm: userspace hugepage collapse Zi Yan
2022-03-21 14:51   ` Zach O'Keefe
2022-03-21 14:37 ` Michal Hocko
2022-03-21 15:46   ` Zach O'Keefe
2022-03-22 12:11     ` Michal Hocko
2022-03-22 15:53       ` Zach O'Keefe
2022-03-29 12:24         ` Michal Hocko
2022-03-30  0:36           ` Zach O'Keefe
2022-03-22  6:40 ` Zach O'Keefe
2022-03-22 12:05   ` Michal Hocko
2022-03-23 13:30     ` Zach O'Keefe

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