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

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Message-Id: <20190813152805.5251-3-joro@8bytes.org>
Date:   Tue, 13 Aug 2019 17:28:04 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org
Cc:     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>,
        linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_all()

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

commit 8e998fc24de47c55b47a887f6c95ab91acd4a720 upstream.

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 and make sure
vmalloc_sync_all() iterates over all page-tables even when an unmapped PMD
is found.

Fixes: 5d72b4fba40ef ('x86, mm: support huge I/O mapping capability I/F')
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>
Link: https://lkml.kernel.org/r/20190719184652.11391-3-joro@8bytes.org
---
 arch/x86/mm/fault.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 4d12176a470e..1bcb7242ad79 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -261,11 +261,12 @@ 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));
 
@@ -287,17 +288,13 @@ void vmalloc_sync_all(void)
 		spin_lock(&pgd_lock);
 		list_for_each_entry(page, &pgd_list, lru) {
 			spinlock_t *pgt_lock;
-			pmd_t *ret;
 
 			/* the pgt_lock only for Xen */
 			pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
 
 			spin_lock(pgt_lock);
-			ret = vmalloc_sync_one(page_address(page), address);
+			vmalloc_sync_one(page_address(page), address);
 			spin_unlock(pgt_lock);
-
-			if (!ret)
-				break;
 		}
 		spin_unlock(&pgd_lock);
 	}
-- 
2.16.4