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Message-Id: <184340f563959728d5e4e3d23463f54b797040b6.1602093760.git.yuleixzhang@tencent.com>
Date: Thu, 8 Oct 2020 15:54:09 +0800
From: yulei.kernel@...il.com
To: akpm@...ux-foundation.org, naoya.horiguchi@....com,
viro@...iv.linux.org.uk, pbonzini@...hat.com
Cc: linux-fsdevel@...r.kernel.org, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, xiaoguangrong.eric@...il.com,
kernellwp@...il.com, lihaiwei.kernel@...il.com,
Yulei Zhang <yuleixzhang@...cent.com>,
Chen Zhuo <sagazchen@...cent.com>
Subject: [PATCH 19/35] mm: gup_huge_pmd() for dmem huge pmd
From: Yulei Zhang <yuleixzhang@...cent.com>
Add pmd_special() check in gup_huge_pmd() to support dmem huge pmd.
GUP will return zero if enconter dmem page, and we could handle it
outside GUP routine.
Signed-off-by: Chen Zhuo <sagazchen@...cent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@...cent.com>
---
mm/gup.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/gup.c b/mm/gup.c
index 726ffc5b0ea9..a8edbb6a2b2f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2440,6 +2440,10 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
return 0;
+ /* Bypass dmem huge pmd. It will be handled in outside routine. */
+ if (pmd_special(orig))
+ return 0;
+
if (pmd_devmap(orig)) {
if (unlikely(flags & FOLL_LONGTERM))
return 0;
@@ -2542,7 +2546,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
return 0;
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) ||
- pmd_devmap(pmd))) {
+ pmd_devmap(pmd) || pmd_special(pmd))) {
/*
* NUMA hinting faults need to be handled in the GUP
* slowpath for accounting purposes and so that they
--
2.28.0
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