Commit 556d74a3 authored by Baolin Wang's avatar Baolin Wang Committed by Liu Shixin
Browse files

mm: page_alloc: use the correct THP order for THP PCP 

next inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9OCYO
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6303d1c553c8d758f068de70a41668622b7a917c

--------------------------------

Commit 44042b44 ("mm/page_alloc: allow high-order pages to be stored
on the per-cpu lists") extends the PCP allocator to store THP pages, and
it determines whether to cache THP pages in PCP by comparing with
pageblock_order.  But the pageblock_order is not always equal to THP
order.  It might also be MAX_PAGE_ORDER, which could prevent PCP from
caching THP pages.

Therefore, using HPAGE_PMD_ORDER instead to determine the need for caching
THP for PCP will fix this issue

Link: https://lkml.kernel.org/r/a25c9e14cd03907d5978b60546a69e6aa3fc2a7d.1712151833.git.baolin.wang@linux.alibaba.com


Fixes: 44042b44 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
Signed-off-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: default avatarBarry Song <baohua@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent a00ba8b5

mm/page_alloc.c

+3 −3
Original line number Diff line number Diff line
@@ -529,7 +529,7 @@ static inline unsigned int order_to_pindex(int migratetype, int order) 
{

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	if (order > PAGE_ALLOC_COSTLY_ORDER) {

		VM_BUG_ON(order != pageblock_order);

		VM_BUG_ON(order != HPAGE_PMD_ORDER);

		return NR_LOWORDER_PCP_LISTS;

	}

#else
@@ -545,7 +545,7 @@ static inline int pindex_to_order(unsigned int pindex) 


#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	if (pindex == NR_LOWORDER_PCP_LISTS)

		order = pageblock_order;

		order = HPAGE_PMD_ORDER;

#else

	VM_BUG_ON(order > PAGE_ALLOC_COSTLY_ORDER);

#endif
@@ -558,7 +558,7 @@ static inline bool pcp_allowed_order(unsigned int order) 
	if (order <= PAGE_ALLOC_COSTLY_ORDER)

		return true;

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	if (order == pageblock_order)

	if (order == HPAGE_PMD_ORDER)

		return true;

#endif

	return false;