From: "Matthew Wilcox (Oracle)" <willy@infradead.org> mainline inclusion from mainline-v5.14-rc1 commit 0f2317e34e2c7b97efd4600122115410795ebeea category: feature bugzilla: 187198, https://gitee.com/openeuler/kernel/issues/I5GVFO CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- If you pass a const pointer to compound_head(), you get a const pointer back; if you pass a mutable pointer, you get a mutable pointer back. Also remove an unnecessary forward definition of struct page; we're about to dereference page->compound_head, so it must already have been defined. Link: https://lkml.kernel.org/r/20210416231531.2521383-5-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Liu Shixin <liushixin2@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- include/linux/page-flags.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 65e1cbe1d1ce..b40b4e0ada31 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -194,17 +194,17 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H -struct page; /* forward declaration */ - -static inline struct page *compound_head(struct page *page) +static inline unsigned long _compound_head(const struct page *page) { unsigned long head = READ_ONCE(page->compound_head); if (unlikely(head & 1)) - return (struct page *) (head - 1); - return page; + return head - 1; + return (unsigned long)page; } +#define compound_head(page) ((typeof(page))_compound_head(page)) + static __always_inline int PageTail(struct page *page) { return READ_ONCE(page->compound_head) & 1; -- 2.20.1