The patch titled
mm: D-cache aliasing issue in cow_user_page
has been added to the -mm tree. Its filename is
mmd-cache-aliasing-issue-in-cow_user_page.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: mm: D-cache aliasing issue in cow_user_page
From: Dmitriy Monakhov <dmonakhov@xxxxxxxxxx>
--=-=-=
from mm/memory.c:
1434 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
1435 {
1436 /*
1437 * If the source page was a PFN mapping, we don't have
1438 * a "struct page" for it. We do a best-effort copy by
1439 * just copying from the original user address. If that
1440 * fails, we just zero-fill it. Live with it.
1441 */
1442 if (unlikely(!src)) {
1443 void *kaddr = kmap_atomic(dst, KM_USER0);
1444 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1445
1446 /*
1447 * This really shouldn't fail, because the page is there
1448 * in the page tables. But it might just be unreadable,
1449 * in which case we just give up and fill the result with
1450 * zeroes.
1451 */
1452 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1453 memset(kaddr, 0, PAGE_SIZE);
1454 kunmap_atomic(kaddr, KM_USER0);
#### D-cache have to be flushed here.
#### It seems it is just forgotten.
1455 return;
1456
1457 }
1458 copy_user_highpage(dst, src, va);
#### Ok here. flush_dcache_page() called from this func if arch need it
1459 }
Following is the patch fix this issue:
Signed-off-by: Dmitriy Monakhov <dmonakhov@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/memory.c | 1 +
1 files changed, 1 insertion(+)
diff -puN mm/memory.c~mmd-cache-aliasing-issue-in-cow_user_page mm/memory.c
--- a/mm/memory.c~mmd-cache-aliasing-issue-in-cow_user_page
+++ a/mm/memory.c
@@ -1452,6 +1452,7 @@ static inline void cow_user_page(struct
if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
memset(kaddr, 0, PAGE_SIZE);
kunmap_atomic(kaddr, KM_USER0);
+ flush_dcache_page(dst);
return;
}
_
Patches currently in -mm which might be from dmonakhov@xxxxxxxxxx are
mmd-cache-aliasing-issue-in-cow_user_page.patch
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