linux-kernel - [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync

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Message-Id: <20190715110212.18617-3-joro@8bytes.org>
Date:   Mon, 15 Jul 2019 13:02:11 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_one()

From: Joerg Roedel <jroedel@...e.de>

With huge-page ioremap areas the unmappings also need to be
synced between all page-tables. Otherwise it can cause data
corruption when a region is unmapped and later re-used.

Make the vmalloc_sync_one() function ready to sync
unmappings.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 arch/x86/mm/fault.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 4a4049f6d458..d71e167662c3 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -194,11 +194,12 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
 
 	pmd = pmd_offset(pud, address);
 	pmd_k = pmd_offset(pud_k, address);
-	if (!pmd_present(*pmd_k))
-		return NULL;
 
-	if (!pmd_present(*pmd))
+	if (pmd_present(*pmd) ^ pmd_present(*pmd_k))
 		set_pmd(pmd, *pmd_k);
+
+	if (!pmd_present(*pmd_k))
+		return NULL;
 	else
 		BUG_ON(pmd_pfn(*pmd) != pmd_pfn(*pmd_k));
 
-- 
2.17.1