Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1535935
| From | Xishi Qiu <qiuxishi@huawei.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [RFC PATCH v2] mm: use ACCESS_ONCE in page_cpupid_xchg_last() |
| Date | 2016-12-05 10:30 +0100 |
| Message-ID | <sKXKW-2Ja-19@gated-at.bofh.it> (permalink) |
| References | <sKWOR-2aU-5@gated-at.bofh.it> <sKWYx-2e2-5@gated-at.bofh.it> <sKXhT-2kv-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
A compiler could re-read "old_flags" from the memory location after reading
and calculation "flags" and passes a newer value into the cmpxchg making
the comparison succeed while it should actually fail.
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
mm/mmzone.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 5652be8..e0b698e 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -102,7 +102,7 @@ int page_cpupid_xchg_last(struct page *page, int cpupid)
int last_cpupid;
do {
- old_flags = flags = page->flags;
+ old_flags = flags = ACCESS_ONCE(page->flags);
last_cpupid = page_cpupid_last(page);
flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
--
1.8.3.1
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[RFC PATCH] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Xishi Qiu <qiuxishi@huawei.com> - 2016-12-05 09:30 +0100
Re: [RFC PATCH] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Christian Borntraeger <borntraeger@de.ibm.com> - 2016-12-05 09:40 +0100
Re: [RFC PATCH] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Christian Borntraeger <borntraeger@de.ibm.com> - 2016-12-05 10:00 +0100
Re: [RFC PATCH] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Xishi Qiu <qiuxishi@huawei.com> - 2016-12-05 10:30 +0100
[RFC PATCH v2] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Xishi Qiu <qiuxishi@huawei.com> - 2016-12-05 10:30 +0100
Re: [RFC PATCH v2] mm: use ACCESS_ONCE in page_cpupid_xchg_last() Christian Borntraeger <borntraeger@de.ibm.com> - 2016-12-05 10:50 +0100
[RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Xishi Qiu <qiuxishi@huawei.com> - 2016-12-06 03:00 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Vlastimil Babka <vbabka@suse.cz> - 2016-12-07 09:40 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Michal Hocko <mhocko@kernel.org> - 2016-12-07 09:50 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Vlastimil Babka <vbabka@suse.cz> - 2016-12-07 09:50 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Michal Hocko <mhocko@kernel.org> - 2016-12-07 10:00 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Vlastimil Babka <vbabka@suse.cz> - 2016-12-07 10:40 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Christian Borntraeger <borntraeger@de.ibm.com> - 2016-12-07 10:50 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Christian Borntraeger <borntraeger@de.ibm.com> - 2016-12-07 11:10 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-12-07 23:20 +0100
Re: [RFC PATCH v3] mm: use READ_ONCE in page_cpupid_xchg_last() Michal Hocko <mhocko@kernel.org> - 2016-12-07 11:10 +0100
csiph-web