Re: [PATCH] mm/slub: Switch slub_debug kernel option to early_param to avoid boot panic

[Christoph Lameter <cl@linux.com>]

On Wed, 6 Nov 2013, Andreas Herrmann wrote:

> When I've used slub_debug kernel option (e.g.
> "slub_debug=,skbuff_fclone_cache" or similar) on a debug session I've
> seen a panic like:

Hmmm.. That looks like its due to some slabs not having names
during early boot. kmem_cache_flags is called with NULL as a parameter.

Are you sure that this fixes the issue? Looks like the
kmem_cache_flag function should fail regardless of how early you set it.

AFAICT the right fix would be:


Subject: slub: Handle NULL parameter in kmem_cache_flags

kmem_cache_flags may be called with NULL parameter during early boot.
Skip the test in that case.

Signed-off-by: Christoph Lameter <cl@linux.com>

Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c	2013-10-15 13:55:44.000000000 -0500
+++ linux/mm/slub.c	2013-11-06 13:09:21.810583134 -0600
@@ -1217,7 +1217,7 @@ static unsigned long kmem_cache_flags(un
 	/*
 	 * Enable debugging if selected on the kernel commandline.
 	 */
-	if (slub_debug && (!slub_debug_slabs ||
+	if (slub_debug && name && (!slub_debug_slabs ||
 		!strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs))))
 		flags |= slub_debug;



--
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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>