On 3/14/2018 11:31 PM, Toshi Kani wrote:
Implement pud_free_pmd_page() and pmd_free_pte_page() on x86, which
clear a given pud/pmd entry and free up lower level page table(s).
Address range associated with the pud/pmd entry must have been purged
by INVLPG.
fixes: e61ce6ade404e ("mm: change ioremap to set up huge I/O mappings")
Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
arch/x86/mm/pgtable.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 1eed7ed518e6..34cda7e0551b 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -712,7 +712,22 @@ int pmd_clear_huge(pmd_t *pmd)
*/
int pud_free_pmd_page(pud_t *pud)
{
- return pud_none(*pud);
+ pmd_t *pmd;
+ int i;
+
+ if (pud_none(*pud))
+ return 1;
+
+ pmd = (pmd_t *)pud_page_vaddr(*pud);
+
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ if (!pmd_free_pte_page(&pmd[i]))
This is forced action and no optional. Also, pmd_free_pte_page()
doesn't return 0 in any case. So, you may remove _if_ ?
+ return 0;
+
+ pud_clear(pud);
+ free_page((unsigned long)pmd);
+
+ return 1;
}
/**
@@ -724,6 +739,15 @@ int pud_free_pmd_page(pud_t *pud)
*/
int pmd_free_pte_page(pmd_t *pmd)
{
- return pmd_none(*pmd);
+ pte_t *pte;
+
+ if (pmd_none(*pmd))
This should also check if pmd is already huge. Same for pud ?
+ return 1;
+
+ pte = (pte_t *)pmd_page_vaddr(*pmd);
+ pmd_clear(pmd);
+ free_page((unsigned long)pte);
+
+ return 1;
}
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
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Chintan
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