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authorVlastimil Babka <vbabka@suse.cz>2019-10-14 14:11:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-10-14 15:04:00 -0700
commit5556cfe8d994d5e7b4d50fd91597b8dc0b3a82fd (patch)
treea3e55b8ba5ff41d419619f44e6d12d52be35e78e /include
parent2abd839aa7e615f2bbc50c8ba7deb9e40d186768 (diff)
mm, page_owner: fix off-by-one error in __set_page_owner_handle()
Patch series "followups to debug_pagealloc improvements through page_owner", v3. These are followups to [1] which made it to Linus meanwhile. Patches 1 and 3 are based on Kirill's review, patch 2 on KASAN request [2]. It would be nice if all of this made it to 5.4 with [1] already there (or at least Patch 1). This patch (of 3): As noted by Kirill, commit 7e2f2a0cd17c ("mm, page_owner: record page owner for each subpage") has introduced an off-by-one error in __set_page_owner_handle() when looking up page_ext for subpages. As a result, the head page page_owner info is set twice, while for the last tail page, it's not set at all. Fix this and also make the code more efficient by advancing the page_ext pointer we already have, instead of calling lookup_page_ext() for each subpage. Since the full size of struct page_ext is not known at compile time, we can't use a simple page_ext++ statement, so introduce a page_ext_next() inline function for that. Link: http://lkml.kernel.org/r/20190930122916.14969-2-vbabka@suse.cz Fixes: 7e2f2a0cd17c ("mm, page_owner: record page owner for each subpage") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Kirill A. Shutemov <kirill@shutemov.name> Reported-by: Miles Chen <miles.chen@mediatek.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Walter Wu <walter-zh.wu@mediatek.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/page_ext.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 682fd465df06..5e856512bafb 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -36,6 +36,7 @@ struct page_ext {
unsigned long flags;
};
+extern unsigned long page_ext_size;
extern void pgdat_page_ext_init(struct pglist_data *pgdat);
#ifdef CONFIG_SPARSEMEM
@@ -52,6 +53,13 @@ static inline void page_ext_init(void)
struct page_ext *lookup_page_ext(const struct page *page);
+static inline struct page_ext *page_ext_next(struct page_ext *curr)
+{
+ void *next = curr;
+ next += page_ext_size;
+ return next;
+}
+
#else /* !CONFIG_PAGE_EXTENSION */
struct page_ext;