[PATCH] Add API for flushing Anon pages
Currently, get_user_pages() returns fully coherent pages to the kernel for
anything other than anonymous pages. This is a problem for things like
fuse and the SCSI generic ioctl SG_IO which can potentially wish to do DMA
to anonymous pages passed in by users.
The fix is to add a new memory management API: flush_anon_page() which
is used in get_user_pages() to make anonymous pages coherent.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt
index 4ae4188..1f312a9 100644
--- a/Documentation/cachetlb.txt
+++ b/Documentation/cachetlb.txt
@@ -362,6 +362,15 @@
likely that you will need to flush the instruction cache
for copy_to_user_page().
+ void flush_anon_page(struct page *page, unsigned long vmaddr)
+ When the kernel needs to access the contents of an anonymous
+ page, it calls this function (currently only
+ get_user_pages()). Note: flush_dcache_page() deliberately
+ doesn't work for an anonymous page. The default
+ implementation is a nop (and should remain so for all coherent
+ architectures). For incoherent architectures, it should flush
+ the cache of the page at vmaddr in the current user process.
+
void flush_icache_range(unsigned long start, unsigned long end)
When the kernel stores into addresses that it will execute
out of (eg when loading modules), this function is called.
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 6bece92..7bd2593 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -7,6 +7,12 @@
#include <asm/cacheflush.h>
+#ifndef ARCH_HAS_FLUSH_ANON_PAGE
+static inline void flush_anon_page(struct page *page, unsigned long vmaddr)
+{
+}
+#endif
+
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
diff --git a/mm/memory.c b/mm/memory.c
index e347e10..6768604 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1071,6 +1071,8 @@
}
if (pages) {
pages[i] = page;
+
+ flush_anon_page(page, start);
flush_dcache_page(page);
}
if (vmas)