The patch titled
Subject: mm/hugetlb: drop vma_has_reserves()
has been added to the -mm mm-unstable branch. Its filename is
mm-hugetlb-drop-vma_has_reserves.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-drop-vma_has_reserves.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/hugetlb: drop vma_has_reserves()
Date: Tue, 7 Jan 2025 15:40:01 -0500
After the previous cleanup, vma_has_reserves() is mostly an empty helper
except that it says "use reserve count" is inverted meaning from "needs a
global reserve count", which is still true.
To avoid confusions on having two inverted ways to ask the same question,
always use the gbl_chg everywhere, and drop the function.
When at it, rename "chg" to "gbl_chg" in dequeue_hugetlb_folio_vma(). It
might be helpful for readers to see that the "chg" here is the global
reserve count, not the vma resv count.
Link: https://lkml.kernel.org/r/20250107204002.2683356-7-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Cc: Breno Leitao <leitao@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 23 ++++++-----------------
1 file changed, 6 insertions(+), 17 deletions(-)
--- a/mm/hugetlb.c~mm-hugetlb-drop-vma_has_reserves
+++ a/mm/hugetlb.c
@@ -1246,16 +1246,6 @@ void clear_vma_resv_huge_pages(struct vm
hugetlb_dup_vma_private(vma);
}
-/* Returns true if the VMA has associated reserve pages */
-static bool vma_has_reserves(long chg)
-{
- /*
- * Now "chg" has all the conditions considered for whether we
- * should use an existing reservation.
- */
- return chg == 0;
-}
-
static void enqueue_hugetlb_folio(struct hstate *h, struct folio *folio)
{
int nid = folio_nid(folio);
@@ -1341,7 +1331,7 @@ static unsigned long available_huge_page
static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
struct vm_area_struct *vma,
- unsigned long address, long chg)
+ unsigned long address, long gbl_chg)
{
struct folio *folio = NULL;
struct mempolicy *mpol;
@@ -1350,11 +1340,10 @@ static struct folio *dequeue_hugetlb_fol
int nid;
/*
- * A child process with MAP_PRIVATE mappings created by their parent
- * have no page reserves. This check ensures that reservations are
- * not "stolen". The child may still get SIGKILLed
+ * gbl_chg==1 means the allocation requires a new page that was not
+ * reserved before. Making sure there's at least one free page.
*/
- if (!vma_has_reserves(chg) && !available_huge_pages(h))
+ if (gbl_chg && !available_huge_pages(h))
goto err;
gfp_mask = htlb_alloc_mask(h);
@@ -1372,7 +1361,7 @@ static struct folio *dequeue_hugetlb_fol
folio = dequeue_hugetlb_folio_nodemask(h, gfp_mask,
nid, nodemask);
- if (folio && vma_has_reserves(chg)) {
+ if (folio && !gbl_chg) {
folio_set_hugetlb_restore_reserve(folio);
h->resv_huge_pages--;
}
@@ -3063,7 +3052,7 @@ struct folio *alloc_hugetlb_folio(struct
if (!folio)
goto out_uncharge_cgroup;
spin_lock_irq(&hugetlb_lock);
- if (vma_has_reserves(gbl_chg)) {
+ if (!gbl_chg) {
folio_set_hugetlb_restore_reserve(folio);
h->resv_huge_pages--;
}
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-hugetlb-fix-avoid_reserve-to-allow-taking-folio-from-subpool.patch
mm-hugetlb-stop-using-avoid_reserve-flag-in-fork.patch
mm-hugetlb-rename-avoid_reserve-to-cow_from_owner.patch
mm-hugetlb-clean-up-map-global-resv-accounting-when-allocate.patch
mm-hugetlb-simplify-vma_has_reserves.patch
mm-hugetlb-drop-vma_has_reserves.patch
mm-hugetlb-unify-restore-reserve-accounting-for-new-allocations.patch
