linux-kernel - [PATCH v3 08/15] mm/pte_ref: initialize the refcount of the withdrawn PTE page table page

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]

Date:   Wed, 10 Nov 2021 16:40:50 +0800
From:   Qi Zheng <zhengqi.arch@...edance.com>
To:     akpm@...ux-foundation.org, tglx@...utronix.de,
        kirill.shutemov@...ux.intel.com, mika.penttila@...tfour.com,
        david@...hat.com, jgg@...dia.com
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, songmuchun@...edance.com,
        zhouchengming@...edance.com, Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v3 08/15] mm/pte_ref: initialize the refcount of the withdrawn PTE page table page

When we split the PMD-mapped THP to the PTE-mapped THP, we should
initialize the refcount of the withdrawn PTE page table page to
HPAGE_PMD_NR, which ensures that we can release the PTE page table
page when it is free(the refcount is 0).

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 mm/pgtable-generic.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 4e640baf9794..523053e09dfa 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -186,6 +186,7 @@ pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
 							  struct page, lru);
 	if (pmd_huge_pte(mm, pmdp))
 		list_del(&pgtable->lru);
+	pte_ref_init(pgtable, pmdp, HPAGE_PMD_NR);
 	return pgtable;
 }
 #endif
-- 
2.11.0