linux-kernel - [PATCH 4.14 074/143] sparc64: Fix regression in pmdp

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Date:   Fri,  2 Nov 2018 19:34:19 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 074/143] sparc64: Fix regression in pmdp_invalidate().

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

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

[ Upstream commit cfb61b5e3e09f8b49bc4d685429df75f45127adc ]

pmdp_invalidate() was changed to update the pmd atomically
(to not lose dirty/access bits) and return the original pmd
value.

However, in doing so, we lost a lot of the essential work that
set_pmd_at() does, namely to update hugepage mapping counts and
queuing up the batched TLB flush entry.

Thus we were not flushing entries out of the TLB when making
such PMD changes.

Fix this by abstracting the accounting work of set_pmd_at() out into a
separate function, and call it from pmdp_establish().

Fixes: a8e654f01cb7 ("sparc64: update pmdp_invalidate() to return old pmd value")
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/sparc/mm/tlb.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
index 847ddffbf38a..b5cfab711651 100644
--- a/arch/sparc/mm/tlb.c
+++ b/arch/sparc/mm/tlb.c
@@ -163,13 +163,10 @@ static void tlb_batch_pmd_scan(struct mm_struct *mm, unsigned long vaddr,
 	pte_unmap(pte);
 }
 
-void set_pmd_at(struct mm_struct *mm, unsigned long addr,
-		pmd_t *pmdp, pmd_t pmd)
-{
-	pmd_t orig = *pmdp;
-
-	*pmdp = pmd;
 
+static void __set_pmd_acct(struct mm_struct *mm, unsigned long addr,
+			   pmd_t orig, pmd_t pmd)
+{
 	if (mm == &init_mm)
 		return;
 
@@ -219,6 +216,15 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	}
 }
 
+void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+		pmd_t *pmdp, pmd_t pmd)
+{
+	pmd_t orig = *pmdp;
+
+	*pmdp = pmd;
+	__set_pmd_acct(mm, addr, orig, pmd);
+}
+
 static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 		unsigned long address, pmd_t *pmdp, pmd_t pmd)
 {
@@ -227,6 +233,7 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 	do {
 		old = *pmdp;
 	} while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd);
+	__set_pmd_acct(vma->vm_mm, address, old, pmd);
 
 	return old;
 }
-- 
2.17.1