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arm64: fix erroneous warnings in page freeing functions

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In pmd_free_pte_page() and pud_free_pmd_page() we try to warn if they
hit a present non-table entry. In both cases we'll warn for non-present
entries, as the VM_WARN_ON() only checks the entry is not a table entry.

This has been observed to result in warnings when booting a v4.19-rc2
kernel under qemu.

Fix this by bailing out earlier for non-present entries.

Fixes: ec28bb9c9b ("arm64: Implement page table free interfaces")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Mark Rutland 2018-09-05 17:38:57 +01:00 committed by Will Deacon
parent 57361846b5
commit fac880c7d0
1 changed files with 6 additions and 4 deletions
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10
arch/arm64/mm/mmu.c
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@ -985,8 +985,9 @@ int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
pmd = READ_ONCE(*pmdp);
/* No-op for empty entry and WARN_ON for valid entry */
if (!pmd_present(pmd) || !pmd_table(pmd)) {
if (!pmd_present(pmd))
return 1;
if (!pmd_table(pmd)) {
VM_WARN_ON(!pmd_table(pmd));
return 1;
}
@ -1007,8 +1008,9 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
pud = READ_ONCE(*pudp);
/* No-op for empty entry and WARN_ON for valid entry */
if (!pud_present(pud) || !pud_table(pud)) {
if (!pud_present(pud))
return 1;
if (!pud_table(pud)) {
VM_WARN_ON(!pud_table(pud));
return 1;
}