XFS memory allocation deadlock in 2.6.38

['Christoph Hellwig']

Can you check if the brute force patch below helps?  If it does I
still need to refine it a bit, but it could be that we are doing
an allocation under an xfs lock that could recurse back into the
filesystem.  We have a per-process flag to disable that for normal
kmalloc allocation, but we lost it for vmalloc in the commit you
bisected the regression to.


Index: xfs/fs/xfs/linux-2.6/kmem.h
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/kmem.h	2011-03-29 21:16:58.039224236 +0200
+++ xfs/fs/xfs/linux-2.6/kmem.h	2011-03-29 21:17:08.368223598 +0200
@@ -63,7 +63,7 @@ static inline void *kmem_zalloc_large(si
 {
 	void *ptr;
 
-	ptr = vmalloc(size);
+	ptr = __vmalloc(size, GFP_NOFS | __GFP_HIGHMEM, PAGE_KERNEL);
 	if (ptr)
 		memset(ptr, 0, size);
 	return ptr;