linux-kernel - [PATCH 4.4 21/43] x86/mm: implement free pmd/pte page interfaces

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Date:   Tue, 27 Mar 2018 18:27:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Toshi Kani <toshi.kani@....com>,
        Lei Li <lious.lilei@...ilicon.com>,
        Michal Hocko <mhocko@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...e.de>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 21/43] x86/mm: implement free pmd/pte page interfaces

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Toshi Kani <toshi.kani@....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@....com>
Reported-by: Lei Li <lious.lilei@...ilicon.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -676,7 +676,22 @@ 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;
 }

 /**
@@ -688,6 +703,15 @@ 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 */