When subpool max_hpages accounting is not enabled, used_hpages is always 0 and might lead to release subpool prematurely because it indicates no pages are used now while there might be.
In order to fix this issue, we should check used_hpages == 0 iff max_hpages accounting is enabled. As max_hpages accounting should be enabled in most common case, this is not worth a Cc stable. Signed-off-by: Hongxiang Lou <[email protected]> Signed-off-by: Miaohe Lin <[email protected]> --- mm/hugetlb.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 777bc0e45bf3..53ea65d1c5ab 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -97,16 +97,26 @@ static inline void ClearPageHugeFreed(struct page *head) /* Forward declaration */ static int hugetlb_acct_memory(struct hstate *h, long delta); -static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) +static inline bool subpool_is_free(struct hugepage_subpool *spool) { - bool free = (spool->count == 0) && (spool->used_hpages == 0); + if (spool->count) + return false; + if (spool->max_hpages != -1) + return spool->used_hpages == 0; + if (spool->min_hpages != -1) + return spool->rsv_hpages == spool->min_hpages; + return true; +} + +static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) +{ spin_unlock(&spool->lock); /* If no pages are used, and no other handles to the subpool * remain, give up any reservations based on minimum size and * free the subpool */ - if (free) { + if (subpool_is_free(spool)) { if (spool->min_hpages != -1) hugetlb_acct_memory(spool->hstate, -spool->min_hpages); -- 2.19.1
