On 3/15/20 9:34 PM, Pingfan Liu wrote:
To better reflect the held state of pages and make code
self-explaining, rename nr as nr_pinned.
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx> Cc: Ira Weiny
<ira.weiny@xxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx> Cc: Dan Williams
<dan.j.williams@xxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx> Cc: "Aneesh Kumar K.V"
<aneesh.kumar@xxxxxxxxxxxxx> Cc: Christoph Hellwig
<hch@xxxxxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> To:
linux-mm@xxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx --- mm/gup.c | 20
++++++++++---------- 1 file changed, 10 insertions(+), 10
deletions(-)
Hi Pingfan,
This is correct as far as it goes, but it doesn't go quite far enough. This should
at least should cover the other caller of gup_pgd_range().
Background: There are two internal-to-gup.c entry points to gup fast:
internal_get_user_pages_fast(), and __get_user_pages_fast(). Quite commonly when
submitting fixes to one of these functions, the other is overlooked, as happened
here.
Here's a diff on top of your patch, that I think should be squashed into your patch:
diff --git a/mm/gup.c b/mm/gup.c
index d0c0d084e792..56052b73abc3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2676,7 +2676,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
{
unsigned long len, end;
unsigned long flags;
- int nr = 0;
+ int nr_pinned = 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.
@@ -2710,11 +2710,11 @@ 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, gup_flags, pages, &nr);
+ gup_pgd_range(start, end, gup_flags, pages, &nr_pinned);
local_irq_restore(flags);
}
- return nr;
+ return nr_pinned;
}
EXPORT_SYMBOL_GPL(__get_user_pages_fast);
With that applied, you can add:
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
thanks,
--
John Hubbard
NVIDIA
diff --git a/mm/gup.c b/mm/gup.c index e8aaa40..9df77b1 100644 ---
a/mm/gup.c +++ b/mm/gup.c @@ -2735,7 +2735,7 @@ static int
internal_get_user_pages_fast(unsigned long start, int nr_pages,
struct page **pages) { unsigned long addr, len, end; - int nr = 0,
ret = 0; + int nr_pinned = 0, ret = 0;
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
FOLL_FORCE | FOLL_PIN | FOLL_GET))) @@ -2754,25 +2754,25 @@ static
int internal_get_user_pages_fast(unsigned long start, int nr_pages,
if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start,
end)) { local_irq_disable(); - gup_pgd_range(addr, end, gup_flags,
pages, &nr); + gup_pgd_range(addr, end, gup_flags, pages,
&nr_pinned); local_irq_enable(); - ret = nr; + ret = nr_pinned; }
- if (nr < nr_pages) { + if (nr_pinned < nr_pages) { /* Try to get
the remaining pages with get_user_pages */ - start += nr <<
PAGE_SHIFT; - pages += nr; + start += nr_pinned << PAGE_SHIFT; +
pages += nr_pinned;
- ret = __gup_longterm_unlocked(start, nr_pages - nr, + ret =
__gup_longterm_unlocked(start, nr_pages - nr_pinned, gup_flags,
pages);
/* Have to be a bit careful with return values */ - if (nr > 0) { +
if (nr_pinned > 0) { if (ret < 0) - ret = nr; + ret =
nr_pinned; else - ret += nr; + ret += nr_pinned; } }
-- 2.7.5
