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Date: Tue, 6 Oct 2015 22:54:31 +0900 From: Minchan Kim <minchan@...nel.org> To: Hui Zhu <zhuhui@...omi.com> Cc: ngupta@...are.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, teawater@...il.com, Andrew Morton <akpm@...ux-foundation.org>, Sergey Senozhatsky <sergey.senozhatsky@...il.com> Subject: Re: [PATCH] zsmalloc: fix obj_to_head use page_private(page) as value but not pointer Hello, On Mon, Oct 05, 2015 at 04:23:01PM +0800, Hui Zhu wrote: > 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 page_private(page); Typo. return *(unsigned long*)page_private(page); Please fix the description. > } else > return *(unsigned long *)obj; > It is used as a pointer. > > So change obj_to_head use page_private(page) as value but not pointer > in obj_to_head. 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> With fixing the comment, Acked-by: Minchan Kim <minchan@...nel.org> Thanks for the fix, Hui. -- Kind regards, Minchan Kim -- 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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