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KVM: s390: Fix unlikely race in try_get_locked_pte()

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Fix an unlikely race in try_get_locked_pte(), which could have happened
if puds or pmds get unmapped between the p?dp_get() and p?d_offset()
functions.

Fixes: 89fa757931 ("KVM: s390: Avoid potentially sleeping while atomic when zapping pages")
CC: stable@vger.kernel.org # 7.1
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260611104850.110313-3-imbrenda@linux.ibm.com>
This commit is contained in:
Claudio Imbrenda 2026-06-11 12:48:47 +02:00
parent f79413b2dd
commit 5670b7f927
1 changed files with 3 additions and 3 deletions
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6
arch/s390/mm/gmap_helpers.c
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@ -51,15 +51,15 @@ pte_t *try_get_locked_pte(struct mm_struct *mm, unsigned long vmaddr, spinlock_t
pgd = pgdp_get(pgdp);
if (pgd_none(pgd) || !pgd_present(pgd))
return NULL;
p4dp = p4d_offset(pgdp, vmaddr);
p4dp = p4d_offset_lockless(pgdp, pgd, vmaddr);
p4d = p4dp_get(p4dp);
if (p4d_none(p4d) || !p4d_present(p4d))
return NULL;
pudp = pud_offset(p4dp, vmaddr);
pudp = pud_offset_lockless(p4dp, p4d, vmaddr);
pud = pudp_get(pudp);
if (pud_none(pud) || pud_leaf(pud) || !pud_present(pud))
return NULL;
pmdp = pmd_offset(pudp, vmaddr);
pmdp = pmd_offset_lockless(pudp, pud, vmaddr);
pmd = pmdp_get_lockless(pmdp);
if (pmd_none(pmd) || pmd_leaf(pmd) || !pmd_present(pmd))
return NULL;