[patch 58/67] mm: bug in set_page_dirty_buffers

Greg KH
2006-10-11T21:16:44Z

[-- Attachment #1: mm-bug-in-set_page_dirty_buffers.patch --]
[-- Type: text/plain, Size: 1335 bytes --]

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Nick Piggin <npiggin@suse.de>

This was triggered, but not the fault of, the dirty page accounting
patches. Suitable for -stable as well, after it goes upstream.

Unable to handle kernel NULL pointer dereference at virtual address 0000004c
EIP is at _spin_lock+0x12/0x66
Call Trace:
[<401766e7>] __set_page_dirty_buffers+0x15/0xc0
[<401401e7>] set_page_dirty+0x2c/0x51
[<40140db2>] set_page_dirty_balance+0xb/0x3b
[<40145d29>] __do_fault+0x1d8/0x279
[<40147059>] __handle_mm_fault+0x125/0x951
[<401133f1>] do_page_fault+0x440/0x59f
[<4034d0c1>] error_code+0x39/0x40
[<08048a33>] 0x8048a33
=======================

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/buffer.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- linux-2.6.18.orig/fs/buffer.c
+++ linux-2.6.18/fs/buffer.c
@@ -838,7 +838,10 @@ EXPORT_SYMBOL(mark_buffer_dirty_inode);
*/
int __set_page_dirty_buffers(struct page *page)
{
- struct address_space * const mapping = page->mapping;
+ struct address_space * const mapping = page_mapping(page);
+
+ if (unlikely(!mapping))
+ return !TestSetPageDirty(page);

spin_lock(&mapping->private_lock);
if (page_has_buffers(page)) {

--