From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>,
"Christoph Hellwig" <hch@infradead.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Dave Chinner" <david@fromorbit.com>,
"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jonathan Corbet" <corbet@lwn.net>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Michal Hocko" <mhocko@suse.com>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Shuah Khan" <shuah@kernel.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Matthew Wilcox" <willy@infradead.org>,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
"John Hubbard" <jhubbard@nvidia.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCH v6 05/12] mm/gup: require FOLL_GET for get_user_pages_fast()
Date: Mon, 10 Feb 2020 16:15:29 -0800 [thread overview]
Message-ID: <20200211001536.1027652-6-jhubbard@nvidia.com> (raw)
In-Reply-To: <20200211001536.1027652-1-jhubbard@nvidia.com>
Internal to mm/gup.c, require that get_user_pages_fast()
and __get_user_pages_fast() identify themselves, by setting
FOLL_GET. This is required in order to be able to make decisions
based on "FOLL_PIN, or FOLL_GET, or both or neither are set", in
upcoming patches.
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
mm/gup.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index e5f75e886663..c8affbea2019 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2390,6 +2390,14 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
unsigned long len, end;
unsigned long flags;
int nr = 0;
+ /*
+ * Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
+ * because gup fast is always a "pin with a +1 page refcount" request.
+ */
+ unsigned int gup_flags = FOLL_GET;
+
+ if (write)
+ gup_flags |= FOLL_WRITE;
start = untagged_addr(start) & PAGE_MASK;
len = (unsigned long) nr_pages << PAGE_SHIFT;
@@ -2415,7 +2423,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
gup_fast_permitted(start, end)) {
local_irq_save(flags);
- gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
+ gup_pgd_range(start, end, gup_flags, pages, &nr);
local_irq_restore(flags);
}
@@ -2454,7 +2462,7 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
int nr = 0, ret = 0;
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
- FOLL_FORCE | FOLL_PIN)))
+ FOLL_FORCE | FOLL_PIN | FOLL_GET)))
return -EINVAL;
start = untagged_addr(start) & PAGE_MASK;
@@ -2521,6 +2529,13 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
return -EINVAL;
+ /*
+ * The caller may or may not have explicitly set FOLL_GET; either way is
+ * OK. However, internally (within mm/gup.c), gup fast variants must set
+ * FOLL_GET, because gup fast is always a "pin with a +1 page refcount"
+ * request.
+ */
+ gup_flags |= FOLL_GET;
return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
}
EXPORT_SYMBOL_GPL(get_user_pages_fast);
--
2.25.0
next prev parent reply other threads:[~2020-02-11 0:16 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 0:15 [PATCH v6 00/12] mm/gup: track FOLL_PIN pages John Hubbard
2020-02-11 0:15 ` [PATCH v6 01/12] mm/gup: split get_user_pages_remote() into two routines John Hubbard
2020-02-11 0:15 ` [PATCH v6 02/12] mm/gup: pass a flags arg to __gup_device_* functions John Hubbard
2020-02-11 0:15 ` [PATCH v6 03/12] mm: introduce page_ref_sub_return() John Hubbard
2020-02-11 0:15 ` [PATCH v6 04/12] mm/gup: pass gup flags to two more routines John Hubbard
2020-02-11 0:15 ` John Hubbard [this message]
2020-02-11 0:15 ` [PATCH v6 06/12] mm/gup: track FOLL_PIN pages John Hubbard
2020-04-24 18:18 ` [regression] " Alex Williamson
2020-04-24 19:20 ` John Hubbard
2020-04-24 20:15 ` Alex Williamson
2020-04-24 22:58 ` John Hubbard
2020-04-28 16:54 ` [regression?] " Alex Williamson
2020-04-28 17:49 ` Jason Gunthorpe
2020-04-28 19:07 ` Alex Williamson
2020-04-28 19:22 ` Jason Gunthorpe
2020-04-28 20:12 ` Alex Williamson
2020-04-29 0:29 ` Jason Gunthorpe
2020-04-29 19:56 ` Alex Williamson
2020-04-29 23:03 ` Jason Gunthorpe
2020-02-11 0:15 ` [PATCH v6 07/12] mm/gup: page->hpage_pinned_refcount: exact pin counts for huge pages John Hubbard
2020-02-11 0:15 ` [PATCH v6 08/12] mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reporting John Hubbard
2020-02-12 9:17 ` Jan Kara
2020-02-11 0:15 ` [PATCH v6 09/12] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2020-02-11 0:15 ` [PATCH v6 10/12] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
2020-02-11 0:15 ` [PATCH v6 11/12] mm: Improve dump_page() for compound pages John Hubbard
2020-02-11 0:15 ` [PATCH v6 12/12] mm: dump_page(): additional diagnostics for huge pinned pages John Hubbard
2020-02-11 13:21 ` Kirill A. Shutemov
2020-02-12 2:10 ` John Hubbard
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