From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 10 Oct 2006 04:36:54 +0200 From: Nick Piggin Subject: [patch] mm: bug in set_page_dirty_buffers Message-ID: <20061010023654.GD15822@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton , Linus Torvalds , Peter Zijlstra , Linux Memory Management List Cc: Greg KH List-ID: 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 Index: linux-2.6/fs/buffer.c =================================================================== --- linux-2.6.orig/fs/buffer.c +++ linux-2.6/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)) { -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org