Thread (3 messages) 3 messages, 1 author, 2015-03-24
STALE4101d REVIEWED: 7 (4M)

[PATCH v2 1/2] mm: Use READ_ONCE() for non-scalar types

From: Jason Low <hidden>
Date: 2015-03-24 22:30:13
Also in: linux-mm, lkml
Subsystem: memory management, memory management - gup (get user pages), the rest · Maintainers: Andrew Morton, David Hildenbrand, Linus Torvalds

Commit 38c5ce936a08 ("mm/gup: Replace ACCESS_ONCE with READ_ONCE")
converted ACCESS_ONCE usage in gup_pmd_range() to READ_ONCE, since
ACCESS_ONCE doesn't work reliably on non-scalar types.

This patch also fixes the other ACCESS_ONCE usages in gup_pte_range()
and __get_user_pages_fast() in mm/gup.c

Signed-off-by: Jason Low <redacted>
Acked-by: Michal Hocko <redacted>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Rik van Riel <redacted>
Reviewed-by: Christian Borntraeger <redacted>
---
 mm/gup.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index ca7b607..6297f6b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1019,7 +1019,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
 		 *
 		 * for an example see gup_get_pte in arch/x86/mm/gup.c
 		 */
-		pte_t pte = ACCESS_ONCE(*ptep);
+		pte_t pte = READ_ONCE(*ptep);
 		struct page *page;
 
 		/*
@@ -1309,7 +1309,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	local_irq_save(flags);
 	pgdp = pgd_offset(mm, addr);
 	do {
-		pgd_t pgd = ACCESS_ONCE(*pgdp);
+		pgd_t pgd = READ_ONCE(*pgdp);
 
 		next = pgd_addr_end(addr, end);
 		if (pgd_none(pgd))
-- 
1.7.1

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