From: Greg KH <gre...@linuxfoundation.org>
3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bob Liu <lliu...@gmail.com>
commit fea9f718b3d68147f162ed2d870183ce5e0ad8d8 upstream.
There is a bug in the below scenario for !CONFIG_MMU:
1. create a new file
2. mmap the file and write to it
3. read the file can't get the correct value
Because
sys_read() -> generic_file_aio_read() -> simple_readpage() -> clear_page()
which causes the page to be zeroed.
Add SetPageUptodate() to ramfs_nommu_expand_for_mapping() so that
generic_file_aio_read() do not call simple_readpage().
Signed-off-by: Bob Liu <lliu...@gmail.com>
Cc: Hugh Dickins <hu...@google.com>
Cc: David Howells <dhowe...@redhat.com>
Cc: Geert Uytterhoeven <ge...@linux-m68k.org>
Cc: Greg Ungerer <g...@uclinux.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
fs/ramfs/file-nommu.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -110,6 +110,7 @@ int ramfs_nommu_expand_for_mapping(struc
/* prevent the page from being discarded on memory pressure */
SetPageDirty(page);
+ SetPageUptodate(page);
unlock_page(page);
put_page(page);
--
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