Commit 12a7bfad authored by Hui Zhu's avatar Hui Zhu Committed by Linus Torvalds

zsmalloc: fix obj_to_head use page_private(page) as value but not pointer

In 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);

In the hugepage we 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 can't be migrated.  However, we need this patch for
future work: "VM-aware zsmalloced page migration" to reduce external
fragmentation.
Signed-off-by: default avatarHui Zhu <zhuhui@xiaomi.com>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8f958c98
......@@ -825,7 +825,7 @@ 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;
}
......
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