The patch titled
Subject: mm/gup: small refactoring: simplify try_grab_page()
has been added to the -mm tree. Its filename is
mm-gup-small-refactoring-simplify-try_grab_page.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-small-refactoring-simplify-try_grab_page.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-small-refactoring-simplify-try_grab_page.patch
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------------------------------------------------------
From: John Hubbard <jhubbard@xxxxxxxxxx>
Subject: mm/gup: small refactoring: simplify try_grab_page()
try_grab_page() does the same thing as try_grab_compound_head(..., refs=1,
...), just with a different API. So there is a lot of code duplication
there.
Change try_grab_page() to call try_grab_compound_head(), while keeping the
API contract identical for callers.
Also, now that try_grab_compound_head() always has a caller, remove the
__maybe_unused annotation.
Link: https://lkml.kernel.org/r/20210813044133.1536842-3-jhubbard@xxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 4 ++--
mm/gup.c | 35 +++++------------------------------
2 files changed, 7 insertions(+), 32 deletions(-)
--- a/include/linux/mm.h~mm-gup-small-refactoring-simplify-try_grab_page
+++ a/include/linux/mm.h
@@ -1214,8 +1214,8 @@ static inline void get_page(struct page
}
bool __must_check try_grab_page(struct page *page, unsigned int flags);
-__maybe_unused struct page *try_grab_compound_head(struct page *page, int refs,
- unsigned int flags);
+struct page *try_grab_compound_head(struct page *page, int refs,
+ unsigned int flags);
static inline __must_check bool try_get_page(struct page *page)
--- a/mm/gup.c~mm-gup-small-refactoring-simplify-try_grab_page
+++ a/mm/gup.c
@@ -124,8 +124,8 @@ static inline struct page *try_get_compo
* considered failure, and furthermore, a likely bug in the caller, so a warning
* is also emitted.
*/
-__maybe_unused struct page *try_grab_compound_head(struct page *page,
- int refs, unsigned int flags)
+struct page *try_grab_compound_head(struct page *page,
+ int refs, unsigned int flags)
{
if (flags & FOLL_GET)
return try_get_compound_head(page, refs);
@@ -208,35 +208,10 @@ static void put_compound_head(struct pag
*/
bool __must_check try_grab_page(struct page *page, unsigned int flags)
{
- WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN));
+ if (!(flags & (FOLL_GET | FOLL_PIN)))
+ return true;
- if (flags & FOLL_GET)
- return try_get_page(page);
- else if (flags & FOLL_PIN) {
- int refs = 1;
-
- page = compound_head(page);
-
- if (WARN_ON_ONCE(page_ref_count(page) <= 0))
- return false;
-
- if (hpage_pincount_available(page))
- hpage_pincount_add(page, 1);
- else
- refs = GUP_PIN_COUNTING_BIAS;
-
- /*
- * Similar to try_grab_compound_head(): even if using the
- * hpage_pincount_add/_sub() routines, be sure to
- * *also* increment the normal page refcount field at least
- * once, so that the page really is pinned.
- */
- page_ref_add(page, refs);
-
- mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED, 1);
- }
-
- return true;
+ return try_grab_compound_head(page, 1, flags);
}
/**
_
Patches currently in -mm which might be from jhubbard@xxxxxxxxxx are
mm-gup-documentation-corrections-for-gup-pup.patch
mm-gup-small-refactoring-simplify-try_grab_page.patch
mm-gup-remove-try_get_page-call-try_get_compound_head-directly.patch
mm-delete-unused-get_kernel_page.patch
