Commit 09a95e29 authored by Mike Kravetz's avatar Mike Kravetz Committed by Linus Torvalds

mm/hugetlb: optimize minimum size (min_size) accounting

It was observed that minimum size accounting associated with the
hugetlbfs min_size mount option may not perform optimally and as
expected.  As huge pages/reservations are released from the filesystem
and given back to the global pools, they are reserved for subsequent
filesystem use as long as the subpool reserved count is less than
subpool minimum size.  It does not take into account used pages within
the filesystem.  The filesystem size limits are not exceeded and this is
technically not a bug.  However, better behavior would be to wait for
the number of used pages/reservations associated with the filesystem to
drop below the minimum size before taking reservations to satisfy
minimum size.

An optimization is also made to the hugepage_subpool_get_pages() routine
which is called when pages/reservations are allocated.  This does not
change behavior, but simply avoids the accounting if all reservations
have already been taken (subpool reserved count == 0).
Signed-off-by: default avatarMike Kravetz <>
Acked-by: default avatarNaoya Horiguchi <>
Cc: Hillf Danton <>
Cc: David Rientjes <>
Cc: Dave Hansen <>
Cc: "Kirill A. Shutemov" <>
Cc: Paul Gortmaker <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 0edaf86c
......@@ -144,7 +144,8 @@ static long hugepage_subpool_get_pages(struct hugepage_subpool *spool,
if (spool->min_hpages != -1) { /* minimum size accounting */
/* minimum size accounting */
if (spool->min_hpages != -1 && spool->rsv_hpages) {
if (delta > spool->rsv_hpages) {
* Asking for more reserves than those already taken on
......@@ -182,7 +183,8 @@ static long hugepage_subpool_put_pages(struct hugepage_subpool *spool,
if (spool->max_hpages != -1) /* maximum size accounting */
spool->used_hpages -= delta;
if (spool->min_hpages != -1) { /* minimum size accounting */
/* minimum size accounting */
if (spool->min_hpages != -1 && spool->used_hpages < spool->min_hpages) {
if (spool->rsv_hpages + delta <= spool->min_hpages)
ret = 0;
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