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From: David Hildenbrand <david@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Xu <peterx@redhat.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	liubo <liubo254@huawei.com>, Matthew Wilcox <willy@infradead.org>,
	Hugh Dickins <hughd@google.com>, Jason Gunthorpe <jgg@ziepe.ca>,
	John Hubbard <jhubbard@nvidia.com>, Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout
Date: Mon, 31 Jul 2023 21:22:26 +0200	[thread overview]
Message-ID: <9a26ce23-9ac7-b111-b700-db0905203c73@redhat.com> (raw)
In-Reply-To: <CAHk-=whxpKc_zOiJ9n-MA9s0wxvU9vRST+iuNYGkHHB6ux48Rg@mail.gmail.com>

On 31.07.23 21:07, Linus Torvalds wrote:
> On Mon, 31 Jul 2023 at 12:00, David Hildenbrand <david@redhat.com> wrote:
>>
>> So in the "!writable" case, we would always call
>> get_user_pages_unlocked() and never honor NUMA faults.
> 
> Ok, so kvm doesn't just use the fast version. Oh well. It was an idea..

Certainly an interesting one, thanks for thinking about possible 
alternatives! Unfortunately, KVM is an advanced GUP user to managed 
secondary MMUs.

I'll get the FOLL_HONOR_NUMA_FAULT patches ready tomorrow and we can 
discuss if that looks better.

(btw, the whole reasoning about "HW would refuse to use these pages" was 
exactly the whole reason I went into the FOLL_FORCE direction ... but 
it's really better to make FOLL_FORCE deal with VMA protection only)

-- 
Cheers,

David / dhildenb


  reply	other threads:[~2023-07-31 19:23 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-27 21:28 [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout David Hildenbrand
2023-07-27 21:28 ` [PATCH v1 1/4] smaps: Fix the abnormal memory statistics obtained through /proc/pid/smaps David Hildenbrand
2023-07-27 21:28 ` [PATCH v1 2/4] mm/gup: Make follow_page() succeed again on PROT_NONE PTEs/PMDs David Hildenbrand
2023-07-28  2:30   ` John Hubbard
2023-07-28  9:08     ` David Hildenbrand
2023-07-28 10:12       ` David Hildenbrand
2023-07-27 21:28 ` [PATCH v1 3/4] smaps: use vm_normal_page_pmd() instead of follow_trans_huge_pmd() David Hildenbrand
2023-07-27 21:28 ` [PATCH v1 4/4] mm/gup: document FOLL_FORCE behavior David Hildenbrand
2023-07-28 16:18 ` [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout Linus Torvalds
2023-07-28 17:30   ` David Hildenbrand
2023-07-28 17:54     ` David Hildenbrand
2023-07-28 19:40     ` David Hildenbrand
2023-07-28 19:50       ` Peter Xu
2023-07-28 20:00         ` David Hildenbrand
2023-08-02 10:24     ` Mel Gorman
2023-07-28 19:39   ` Peter Xu
2023-07-28 19:52     ` David Hildenbrand
2023-07-28 20:23     ` Linus Torvalds
2023-07-28 20:33       ` David Hildenbrand
2023-07-28 20:50         ` Linus Torvalds
2023-07-28 21:02           ` David Hildenbrand
2023-07-28 21:20             ` Peter Xu
2023-07-28 21:31               ` David Hildenbrand
2023-07-28 22:14                 ` Jason Gunthorpe
2023-07-31 16:01                   ` Peter Xu
2023-07-28 21:32               ` John Hubbard
2023-07-28 21:49                 ` Peter Xu
2023-07-28 22:00                   ` John Hubbard
2023-07-31 16:05                     ` Peter Xu
     [not found]   ` <412bb30f-0417-802c-3fc4-a4e9d5891c5d@redhat.com>
2023-07-29  9:35     ` David Hildenbrand
2023-07-31 16:10       ` Peter Xu
2023-07-31 16:20         ` David Hildenbrand
2023-07-31 18:23           ` Linus Torvalds
2023-07-31 18:51             ` Peter Xu
2023-07-31 19:00             ` David Hildenbrand
2023-07-31 19:07               ` Linus Torvalds
2023-07-31 19:22                 ` David Hildenbrand [this message]
2023-08-01 13:05               ` Jason Gunthorpe

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