From: Thomas Hellstrom <thellstrom@vmware.com>
Date: Fri, 4 Oct 2019 09:04:43 +0000 (+0200)
Subject: mm: pagewalk: Take the pagetable lock in walk_pte_range()
X-Git-Tag: v5.15~5042^2^2~6
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ace88f1018b88167a78bafd545d30816d6e207bf;p=platform%2Fkernel%2Flinux-starfive.git

mm: pagewalk: Take the pagetable lock in walk_pte_range()

Without the lock, anybody modifying a pte from within this function might
have it concurrently modified by someone else.

Cc: Matthew Wilcox <willy@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index d48c2a9..c5fa42c 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -10,8 +10,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 	pte_t *pte;
 	int err = 0;
 	const struct mm_walk_ops *ops = walk->ops;
+	spinlock_t *ptl;
 
-	pte = pte_offset_map(pmd, addr);
+	pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
 	for (;;) {
 		err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
 		if (err)
@@ -22,7 +23,7 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		pte++;
 	}
 
-	pte_unmap(pte);
+	pte_unmap_unlock(pte, ptl);
 	return err;
 }