linux-kernel - [tip:x86/urgent] x86/mm: Sync also unmappings in vmalloc_sync

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Date:   Mon, 22 Jul 2019 01:22:50 -0700
From:   tip-bot for Joerg Roedel <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jroedel@...e.de, hpa@...or.com,
        dave.hansen@...ux.intel.com, mingo@...nel.org, tglx@...utronix.de
Subject: [tip:x86/urgent] x86/mm: Sync also unmappings in vmalloc_sync_all()

Commit-ID:  8e998fc24de47c55b47a887f6c95ab91acd4a720
Gitweb:     https://git.kernel.org/tip/8e998fc24de47c55b47a887f6c95ab91acd4a720
Author:     Joerg Roedel <jroedel@...e.de>
AuthorDate: Fri, 19 Jul 2019 20:46:51 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Mon, 22 Jul 2019 10:18:30 +0200

x86/mm: Sync also unmappings in vmalloc_sync_all()

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 e64173db4970..9ceacd1156db 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -177,11 +177,12 @@ 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));
 
@@ -203,17 +204,13 @@ 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);
 	}