linux-kernel - [RFC PATCH 2/3] mm: hugetlb: Refactor vma_has_reserves() to should_use_hstate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3d1946d01f63104de913c0979b5a596e2add1672.1728684491.git.ackerleytng@google.com>
Date: Fri, 11 Oct 2024 23:22:37 +0000
From: Ackerley Tng <ackerleytng@...gle.com>
To: muchun.song@...ux.dev, peterx@...hat.com, akpm@...ux-foundation.org, 
	rientjes@...gle.com, fvdl@...gle.com, jthoughton@...gle.com, david@...hat.com
Cc: isaku.yamahata@...el.com, zhiquan1.li@...el.com, fan.du@...el.com, 
	jun.miao@...el.com, tabba@...gle.com, quic_eberman@...cinc.com, 
	roypat@...zon.co.uk, jgg@...dia.com, jhubbard@...dia.com, seanjc@...gle.com, 
	pbonzini@...hat.com, erdemaktas@...gle.com, vannapurve@...gle.com, 
	ackerleytng@...gle.com, pgonda@...gle.com, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org
Subject: [RFC PATCH 2/3] mm: hugetlb: Refactor vma_has_reserves() to should_use_hstate_resv()

With the addition of the chg parameter, vma_has_reserves() no longer
just determines whether the vma has reserves.

The comment in the vma->vm_flags & VM_NORESERVE block indicates that
this function actually computes whether or not the reserved count
should be decremented.

This refactoring also takes into account the allocation's request
parameter avoid_reserve, which helps to further simplify the calling
function alloc_hugetlb_folio().

Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
---
 mm/hugetlb.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 73165c670739..47c421eba112 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1246,9 +1246,19 @@ void clear_vma_resv_huge_pages(struct vm_area_struct *vma)
 	hugetlb_dup_vma_private(vma);
 }

-/* Returns true if the VMA has associated reserve pages */
-static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
+/*
+ * Returns true if this allocation should use (debit) hstate reservations, based on
+ *
+ * @vma: VMA config
+ * @chg: Whether the page requirement can be satisfied using subpool reservations
+ * @avoid_reserve: Whether allocation was requested to avoid using reservations
+ */
+static bool should_use_hstate_resv(struct vm_area_struct *vma, long chg,
+				   bool avoid_reserve)
 {
+	if (avoid_reserve)
+		return false;
+
 	if (vma->vm_flags & VM_NORESERVE) {
 		/*
 		 * This address is already reserved by other process(chg == 0),
@@ -3025,7 +3035,7 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
 	if (ret)
 		goto out_uncharge_cgroup_reservation;

-	use_hstate_resv = !avoid_reserve && vma_has_reserves(vma, gbl_chg);
+	use_hstate_resv = should_use_hstate_resv(vma, gbl_chg, avoid_reserve);

 	spin_lock_irq(&hugetlb_lock);
 	folio = dequeue_hugetlb_folio_vma(h, vma, addr, use_hstate_resv);
--
2.47.0.rc1.288.g06298d1525-goog