The patch titled
Subject: mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3
has been added to the -mm tree. Its filename is
mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3.patch
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------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3
- add PageHuge check in dissolve_free_huge_page() outside hugetlb_lock
- update comment on dissolve_free_huge_page() about return value
Link: http://lkml.kernel.org/r/1560761476-4651-3-git-send-email-n-horiguchi@xxxxxxxxxxxxx
Reported-by: Chen, Jerry T <jerry.t.chen@xxxxxxxxx>
Tested-by: Chen, Jerry T <jerry.t.chen@xxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining")
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Xishi Qiu <xishi.qiuxishi@xxxxxxxxxxxxxxx>
Cc: "Chen, Jerry T" <jerry.t.chen@xxxxxxxxx>
Cc: "Zhuo, Qiuxu" <qiuxu.zhuo@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.19+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/mm/hugetlb.c~mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3
+++ a/mm/hugetlb.c
@@ -1510,14 +1510,22 @@ static int free_pool_huge_page(struct hs
/*
* Dissolve a given free hugepage into free buddy pages. This function does
- * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
- * dissolution fails because a give page is not a free hugepage, or because
- * free hugepages are fully reserved.
+ * nothing for in-use hugepages and non-hugepages.
+ * This function returns values like below:
+ *
+ * -EBUSY: failed to dissolved free hugepages or the hugepage is in-use
+ * (allocated or reserved.)
+ * 0: successfully dissolved free hugepages or the page is not a
+ * hugepage (considered as already dissolved)
*/
int dissolve_free_huge_page(struct page *page)
{
int rc = -EBUSY;
+ /* Not to disrupt normal path by vainly holding hugetlb_lock */
+ if (!PageHuge(page))
+ return 0;
+
spin_lock(&hugetlb_lock);
if (!PageHuge(page)) {
rc = 0;
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
mm-soft-offline-return-ebusy-if-set_hwpoison_free_buddy_page-fails.patch
mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge.patch
mm-hugetlb-soft-offline-dissolve_free_huge_page-return-zero-on-pagehuge-v3.patch
