From ebf7a227dd1d810203a19642655d2fa293f395dd Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 10 Oct 2006 04:36:54 +0200 Subject: [PATCH] mm: bug in set_page_dirty_buffers 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 Signed-off-by: Linus Torvalds --- fs/buffer.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/buffer.c b/fs/buffer.c index 16cfbcd254f1..eeb8ac1aa856 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -701,7 +701,10 @@ 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)) { -- cgit v1.2.3