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); } /** _
