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        sean.j.christopherson@intel.com, xiaoguangrong.eric@gmail.com,
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        Yulei Zhang <yuleixzhang@tencent.com>,
        Chen Zhuo <sagazchen@tencent.com>
Subject: [RFC V2 15/37] mm: add pmd_special() check for pmd_trans_huge_lock()
Date:   Mon,  7 Dec 2020 19:31:08 +0800
Message-Id: <789d8a9a23887c20e4966b6e1c9b52a320ab87af.1607332046.git.yuleixzhang@tencent.com>
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From: Yulei Zhang <yuleixzhang@tencent.com>

As dmem-pmd had been distinguished from thp-pmd, we need to add
pmd_special() such that pmd_trans_huge_lock could fetch ptl
for dmem huge pmd and treat it as stable pmd.

Signed-off-by: Chen Zhuo <sagazchen@tencent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
---
 include/linux/huge_mm.h | 3 ++-
 mm/huge_memory.c        | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 0365aa9..2514b90 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -242,7 +242,8 @@ static inline int is_swap_pmd(pmd_t pmd)
 static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
 		struct vm_area_struct *vma)
 {
-	if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd))
+	if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd)
+		|| pmd_devmap(*pmd) || pmd_special(*pmd))
 		return __pmd_trans_huge_lock(pmd, vma);
 	else
 		return NULL;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9474dbc..31f9e83 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1890,7 +1890,7 @@ spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
 	spinlock_t *ptl;
 	ptl = pmd_lock(vma->vm_mm, pmd);
 	if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
-			pmd_devmap(*pmd)))
+			pmd_devmap(*pmd) || pmd_special(*pmd)))
 		return ptl;
 	spin_unlock(ptl);
 	return NULL;
-- 
1.8.3.1