All of lore.kernel.org
 help / color / mirror / Atom feed
From: Peter Xu <peterx@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	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@techsingularity.net>
Subject: Re: [PATCH v1 0/4] smaps / mm/gup: fix gup_can_follow_protnone fallout
Date: Fri, 28 Jul 2023 15:50:29 -0400	[thread overview]
Message-ID: <ZMQcBWvjVUEBU6mF@x1n> (raw)
In-Reply-To: <b647fd9a-3d75-625c-9f2c-dd3c251528c4@redhat.com>

On Fri, Jul 28, 2023 at 09:40:54PM +0200, David Hildenbrand wrote:
> Hmm. So three alternatives I see:
> 
> 1) Use FOLL_FORCE in follow_page() to unconditionally disable protnone
>    checks. Alternatively, have an internal FOLL_NO_PROTNONE flag if we
>    don't like that.
> 
> 2) Revert the commit and reintroduce unconditional FOLL_NUMA without
>    FOLL_FORCE.
> 
> 3) Have a FOLL_NUMA that callers like KVM can pass.

I'm afraid 3) means changing numa balancing to opt-in, probably no-go for
any non-kvm gup users as that could start to break there, even if making
smaps/follow_page happy again.

I keep worrying 1) on FOLL_FORCE abuse.

So I keep my vote on 2).

Thanks,

-- 
Peter Xu


  reply	other threads:[~2023-07-28 19:51 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 [this message]
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
2023-08-01 13:05               ` Jason Gunthorpe

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=ZMQcBWvjVUEBU6mF@x1n \
    --to=peterx@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=david@redhat.com \
    --cc=hughd@google.com \
    --cc=jgg@ziepe.ca \
    --cc=jhubbard@nvidia.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=liubo254@huawei.com \
    --cc=mgorman@techsingularity.net \
    --cc=torvalds@linux-foundation.org \
    --cc=willy@infradead.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.