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Message-ID: <1444193152-17473-1-git-send-email-zhuhui@xiaomi.com> Date: Wed, 7 Oct 2015 12:45:52 +0800 From: Hui Zhu <zhuhui@...omi.com> To: <minchan@...nel.org>, <ngupta@...are.org>, <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org> CC: <teawater@...il.com>, <akpm@...ux-foundation.org>, <sergey.senozhatsky@...il.com>, Hui Zhu <zhuhui@...omi.com> Subject: [PATCH v2] zsmalloc: fix obj_to_head use page_private(page) as value but not pointer In function obj_malloc: if (!class->huge) /* record handle in the header of allocated chunk */ link->handle = handle; else /* record handle in first_page->private */ set_page_private(first_page, handle); The huge's page save handle to private directly. But in obj_to_head: if (class->huge) { VM_BUG_ON(!is_first_page(page)); return *(unsigned long *)page_private(page); } else return *(unsigned long *)obj; It is used as a pointer. The reason why there is no problem until now is huge-class page is born with ZS_FULL so it couldn't be migrated. Therefore, it shouldn't be real bug in practice. However, we need this patch for future-work "VM-aware zsmalloced page migration" to reduce external fragmentation. Signed-off-by: Hui Zhu <zhuhui@...omi.com> Acked-by: Minchan Kim <minchan@...nel.org> --- mm/zsmalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index f135b1b..e881d4f 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -824,7 +824,7 @@ static unsigned long obj_to_head(struct size_class *class, struct page *page, { if (class->huge) { VM_BUG_ON(!is_first_page(page)); - return *(unsigned long *)page_private(page); + return page_private(page); } else return *(unsigned long *)obj; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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