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arm64: Restrict pagetable teardown to avoid false warning

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commit 650768c512faba8070bf4cfbb28c95eb5cd203f3 upstream.

Commit 9c006972c3 ("arm64: mmu: drop pXd_present() checks from
pXd_free_pYd_table()") removes the pxd_present() checks because the
caller checks pxd_present(). But, in case of vmap_try_huge_pud(), the
caller only checks pud_present(); pud_free_pmd_page() recurses on each
pmd through pmd_free_pte_page(), wherein the pmd may be none. Thus it is
possible to hit a warning in the latter, since pmd_none => !pmd_table().
Thus, add a pmd_present() check in pud_free_pmd_page().

This problem was found by code inspection.

Fixes: 9c006972c3 ("arm64: mmu: drop pXd_present() checks from pXd_free_pYd_table()")
Cc: stable@vger.kernel.org
Reported-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/r/20250527082633.61073-1-dev.jain@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dev Jain
2025-05-27 13:56:33 +05:30
committed by Greg Kroah-Hartman
parent 66bde385a1
commit 6562806f32
1 changed files with 2 additions and 1 deletions
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3
arch/arm64/mm/mmu.c
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@@ -1253,7 +1253,8 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
next = addr;
end = addr + PUD_SIZE;
do {
pmd_free_pte_page(pmdp, next);
if (pmd_present(pmdp_get(pmdp)))
pmd_free_pte_page(pmdp, next);
} while (pmdp++, next += PMD_SIZE, next != end);
pud_clear(pudp);