From: Jason Gunthorpe <jgg@nvidia.com>
To: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>,
David Hildenbrand <david@redhat.com>,
David Howells <dhowells@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
linux-mm@kvack.org, "Mike Rapoport (IBM)" <rppt@kernel.org>
Subject: Re: [PATCH v2 01/13] mm/gup: have internal functions get the mmap_read_lock()
Date: Wed, 25 Jan 2023 12:38:42 -0400 [thread overview]
Message-ID: <Y9FbEsA76ba7BV+q@nvidia.com> (raw)
In-Reply-To: <53ac3700-6532-a609-ceff-d0840469e532@nvidia.com>
On Tue, Jan 24, 2023 at 06:11:36PM -0800, John Hubbard wrote:
> On 1/24/23 12:34, Jason Gunthorpe wrote:
> ...
> > @@ -3183,11 +3198,13 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
> > /* FOLL_GET and FOLL_PIN are mutually exclusive. */
> > if (WARN_ON_ONCE(gup_flags & FOLL_GET))
> > return -EINVAL;
> > + int locked = 0;
> > if (WARN_ON_ONCE(!pages))
> > return -EINVAL;
> > - gup_flags |= FOLL_PIN;
> > - return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
> > + gup_flags |= FOLL_PIN | FOLL_TOUCH;
>
> I missed this on my review of v1 of this series: the FOLL_TOUCH change
> looks like a mistake, yes? It should just be left as-is:
>
> gup_flags |= FOLL_PIN;
>
No, not a mistake.
The transformation is this:
- return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
+ gup_flags |= FOLL_PIN | FOLL_TOUCH;
+ return __gup_longterm_locked(current->mm, start, nr_pages, pages, NULL,
+ &locked, gup_flags);
Ie we switch get_user_pages_unlocked() for __gup_longterm_locked()
Howevr get_user_pages_unlocked() was adding the FOLL_TOUCH before
calling __gup_longterm_locked():
- ret = __gup_longterm_locked(mm, start, nr_pages, pages, NULL, &locked,
- gup_flags | FOLL_TOUCH);
Thus we have to lift the FOLL_TOUCH when we do the function call
replacement.
Jason
next prev parent reply other threads:[~2023-01-25 16:38 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-24 20:34 [PATCH v2 00/13] Simplify the external interface for GUP Jason Gunthorpe
2023-01-24 20:34 ` [PATCH v2 01/13] mm/gup: have internal functions get the mmap_read_lock() Jason Gunthorpe
2023-01-25 2:11 ` John Hubbard
2023-01-25 2:52 ` John Hubbard
2023-01-25 16:38 ` Jason Gunthorpe [this message]
2023-01-25 18:48 ` John Hubbard
2023-01-24 20:34 ` [PATCH v2 02/13] mm/gup: remove obsolete FOLL_LONGTERM comment Jason Gunthorpe
2023-01-25 2:13 ` John Hubbard
2023-02-08 14:25 ` David Hildenbrand
2023-01-24 20:34 ` [PATCH v2 03/13] mm/gup: don't call __gup_longterm_locked() if FOLL_LONGTERM cannot be set Jason Gunthorpe
2023-02-08 14:26 ` David Hildenbrand
2023-01-24 20:34 ` [PATCH v2 04/13] mm/gup: move try_grab_page() to mm/internal.h Jason Gunthorpe
2023-01-25 2:15 ` John Hubbard
2023-02-08 14:26 ` David Hildenbrand
2023-01-24 20:34 ` [PATCH v2 05/13] mm/gup: simplify the external interface functions and consolidate invariants Jason Gunthorpe
2023-01-25 2:30 ` John Hubbard
2023-01-24 20:34 ` [PATCH v2 06/13] mm/gup: add an assertion that the mmap lock is locked Jason Gunthorpe
2023-01-25 2:34 ` John Hubbard
2023-01-24 20:34 ` [PATCH v2 07/13] mm/gup: remove locked being NULL from faultin_vma_page_range() Jason Gunthorpe
2023-01-25 2:38 ` John Hubbard
2023-01-24 20:34 ` [PATCH v2 08/13] mm/gup: add FOLL_UNLOCKABLE Jason Gunthorpe
2023-01-24 20:34 ` [PATCH v2 09/13] mm/gup: make locked never NULL in the internal GUP functions Jason Gunthorpe
2023-01-25 3:00 ` John Hubbard
2023-01-24 20:34 ` [PATCH v2 10/13] mm/gup: remove pin_user_pages_fast_only() Jason Gunthorpe
2023-01-24 20:34 ` [PATCH v2 11/13] mm/gup: make get_user_pages_fast_only() return the common return value Jason Gunthorpe
2023-01-24 20:34 ` [PATCH v2 12/13] mm/gup: move gup_must_unshare() to mm/internal.h Jason Gunthorpe
2023-01-25 2:41 ` John Hubbard
2023-01-26 11:29 ` David Hildenbrand
2023-01-24 20:34 ` [PATCH v2 13/13] mm/gup: move private gup FOLL_ flags to internal.h Jason Gunthorpe
2023-01-25 2:44 ` John Hubbard
2023-01-26 12:48 ` David Hildenbrand
2023-01-26 12:55 ` Jason Gunthorpe
2023-01-26 13:06 ` David Hildenbrand
2023-01-26 14:41 ` Claudio Imbrenda
2023-01-26 14:46 ` David Hildenbrand
2023-01-26 15:05 ` Jason Gunthorpe
2023-01-26 15:39 ` Claudio Imbrenda
2023-01-26 16:35 ` Jason Gunthorpe
2023-01-26 17:24 ` Claudio Imbrenda
2023-01-30 18:21 ` Claudio Imbrenda
2023-01-30 18:24 ` Jason Gunthorpe
2023-02-07 11:31 ` Claudio Imbrenda
2023-02-07 12:40 ` Jason Gunthorpe
2023-02-06 23:46 ` [PATCH v2 00/13] Simplify the external interface for GUP Jason Gunthorpe
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