Re: XFS Bug null pointer dereference in xfs_free_ag_extent

[Joe Jin]

At XFS have a debug option, but I wonder why why it was not opened,
and you may open the option with follow patch, rebuild kernel, you
maybe get more information of it.
And when I trace the code, I also found at some function should check
the return value, it also include the patch.
Hope help for you.



On 7/31/06, kernel <linux@xxxxxxxxxxxx> wrote:
> I format the same partition and restart the testing server before each
> testing.
> I'vs tested on each format at least twenty times.
> With XFS and SAN, This crash happens on every bonnie++ testing.
>
> And I have tested such things on another mathine, results are same.
>
>
> Nathan Scott wrote:
> > On Mon, Jul 31, 2006 at 02:21:10PM +0800, kernel wrote:
> >
> >> Test again......very strange.
> >> I can easily reproduce it on the XFS with SAN(FLX380) connected with a
> >> qlogic 2400 FC card.
> >>
> >
> > Eggshellent... can you reproduce it with each of those changes
> > (below) backed out of your tree please?  Else, git bisect is our
> > next best bet.  Thanks!
> >
> >
> >>> Is this easily reproducible for you?  I've not seen it before, and
> >>> the only possibly related recent changes I can think of are these:
> >>>
> >>> http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e63a3690013a475746ad2cea998ebb534d825704
> >>>
> >>> http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d210a28cd851082cec9b282443f8cc0e6fc09830
> >>>
> >>> Could you try reverting each of those to see if either is the cause?
> >>>
> >
> > cheers.
> >
> >
> -
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--
Regards,
Joe.Jin
--- linux-2.6.18-rc3/fs/xfs/Kconfig	2006-07-30 14:15:36.000000000 +0800
+++ linux.new/fs/xfs/Kconfig	2006-07-31 16:22:32.000000000 +0800
@@ -17,6 +17,15 @@
 	  system of your root partition is compiled as a module, you'll need
 	  to use an initial ramdisk (initrd) to boot.
 
+config XFS_DEBUG
+	bool "XFS debugging"
+	depends on XFS_FS
+	help
+	  If you are experiencing any problems with the XFS filesystem, say
+	  Y here.  This will result in additional debugging messages to be
+	  written to the system log.  Under normal circumstances, this
+	  results in very little overhead.
+
 config XFS_QUOTA
 	bool "XFS Quota support"
 	depends on XFS_FS
--- linux-2.6.18-rc3/fs/xfs/xfs_btree.c	2006-07-30 14:15:36.000000000 +0800
+++ linux.new/fs/xfs/xfs_btree.c	2006-07-31 15:39:43.000000000 +0800
@@ -586,6 +586,9 @@
 	 * Allocate a new cursor.
 	 */
 	cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);
+	if(!cur)
+		return NULL;
+
 	/*
 	 * Deduce the number of btree levels from the arguments.
 	 */
--- linux-2.6.18-rc3/fs/xfs/xfs_alloc.c	2006-07-30 14:15:36.000000000 +0800
+++ linux.new/fs/xfs/xfs_alloc.c	2006-07-31 16:09:04.000000000 +0800
@@ -649,6 +649,9 @@
 	 */
 	bno_cur = xfs_btree_init_cursor(args->mp, args->tp, args->agbp,
 		args->agno, XFS_BTNUM_BNO, NULL, 0);
+	if(!bno_cur)
+		return XFS_ERROR(ENOMEM);
+	
 	/*
 	 * Lookup bno and minlen in the btree (minlen is irrelevant, really).
 	 * Look for the closest free block <= bno, it must contain bno