linux-kernel - [PATCH v4 20/36] mm: Make prep_transhuge

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200515131656.12890-21-willy@infradead.org>
Date:   Fri, 15 May 2020 06:16:40 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH v4 20/36] mm: Make prep_transhuge_page return its argument

From: "Matthew Wilcox (Oracle)" <willy@...radead.org>

By permitting NULL or order-0 pages as an argument, and returning the
argument, callers can write:

	return prep_transhuge_page(alloc_pages(...));

instead of assigning the result to a temporary variable and conditionally
passing that to prep_transhuge_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 include/linux/huge_mm.h | 7 +++++--
 mm/huge_memory.c        | 9 +++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 1f6245091917..6a8502278f41 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -193,7 +193,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp,
 		unsigned long addr, unsigned long len, unsigned long pgoff,
 		unsigned long flags);
 
-extern void prep_transhuge_page(struct page *page);
+extern struct page *prep_transhuge_page(struct page *page);
 extern void free_transhuge_page(struct page *page);
 bool is_transparent_hugepage(struct page *page);
 
@@ -358,7 +358,10 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
 	return false;
 }
 
-static inline void prep_transhuge_page(struct page *page) {}
+static inline struct page *prep_transhuge_page(struct page *page)
+{
+	return page;
+}
 
 static inline bool is_transparent_hugepage(struct page *page)
 {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6ecd1045113b..7a5e2b470bc7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -508,15 +508,20 @@ static inline struct deferred_split *get_deferred_split_queue(struct page *page)
 }
 #endif
 
-void prep_transhuge_page(struct page *page)
+struct page *prep_transhuge_page(struct page *page)
 {
+	if (!page || compound_order(page) == 0)
+		return page;
 	/*
-	 * we use page->mapping and page->indexlru in second tail page
+	 * we use page->mapping and page->index in second tail page
 	 * as list_head: assuming THP order >= 2
 	 */
+	BUG_ON(compound_order(page) == 1);
 
 	INIT_LIST_HEAD(page_deferred_list(page));
 	set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
+
+	return page;
 }
 
 bool is_transparent_hugepage(struct page *page)
-- 
2.26.2