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Subject[PATCH 4.15 050/105] x86/mm: implement free pmd/pte page interfaces
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Toshi Kani <toshi.kani@hpe.com>

commit 28ee90fe6048fa7b7ceaeb8831c0e4e454a4cf89 upstream.

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).

The address range associated with the pud/pmd entry must have been
purged by INVLPG.

Link: http://lkml.kernel.org/r/20180314180155.19492-3-toshi.kani@hpe.com
Fixes: e61ce6ade404e ("mm: change ioremap to set up huge I/O mappings")
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Reported-by: Lei Li <lious.lilei@hisilicon.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/mm/pgtable.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)

--- 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]))
+ 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))
+ 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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