linux-kernel - [PATCH] mm/gup: fix gup_pud

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Message-Id: <1666289686-22798-1-git-send-email-ssengar@linux.microsoft.com>
Date:   Thu, 20 Oct 2022 11:14:46 -0700
From:   Saurabh Sengar <ssengar@...ux.microsoft.com>
To:     ssengar@...rosoft.com, akpm@...ux-foundation.org,
        yuzhao@...gle.com, jack@...e.cz, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, jostarks@...rosoft.com
Subject: [PATCH] mm/gup: fix gup_pud_range() for dax

From: John Starks <jostarks@...rosoft.com>

For dax pud, pud_huge() returns true on x86. So the function works as long
as hugetlb is configured. However, dax doesn't depend on hugetlb.
Commit 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax") fixed
devmap-backed huge PMDs, but missed devmap-backed huge PUDs. Fix this as
well.

Fixes: 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax")
Signed-off-by: John Starks <jostarks@...rosoft.com>
Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
---
 mm/gup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index 05068d3d2557..9e07aa54a4cd 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2687,7 +2687,7 @@ static int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, unsigned lo
 		next = pud_addr_end(addr, end);
 		if (unlikely(!pud_present(pud)))
 			return 0;
-		if (unlikely(pud_huge(pud))) {
+		if (unlikely(pud_huge(pud) || pud_devmap(pud))) {
 			if (!gup_huge_pud(pud, pudp, addr, next, flags,
 					  pages, nr))
 				return 0;
-- 
2.25.1