Re: Re: 2.6.37-rc1 mainline domU - BUG: unable to handle kernel paging request

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 12/01/2010 01:32 PM, Bruce Edge wrote:
> I just checked the recently released 2.6.73-rc4,

Do you mean mainline 2.6.37-rc4, or the one in xen/next-2.6.37?

>  and while the BUG
> signature is different, it still fails under NFS accesses. This is
> 100% recreatable.

Please try this patch which is queued up for mainline.  It's already in
xen/next-2.6.37.

    J


diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 21ed8d7..0e4ecac 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2358,8 +2358,6 @@ void __init xen_init_mmu_ops(void)
 	x86_init.paging.pagetable_setup_done = xen_pagetable_setup_done;
 	pv_mmu_ops = xen_mmu_ops;
 
-	vmap_lazy_unmap = false;
-
 	memset(dummy_mapping, 0xff, PAGE_SIZE);
 }
 
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index a03dcf6..44b54f6 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -7,8 +7,6 @@
 
 struct vm_area_struct;		/* vma defining user mapping in mm_types.h */
 
-extern bool vmap_lazy_unmap;
-
 /* bits in flags of vmalloc's vm_struct below */
 #define VM_IOREMAP	0x00000001	/* ioremap() and friends */
 #define VM_ALLOC	0x00000002	/* vmalloc() */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a3d66b3..eb5cc7d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -31,8 +31,6 @@
 #include <asm/tlbflush.h>
 #include <asm/shmparam.h>
 
-bool vmap_lazy_unmap __read_mostly = true;
-
 /*** Page table manipulation functions ***/
 
 static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
@@ -503,9 +501,6 @@ static unsigned long lazy_max_pages(void)
 {
 	unsigned int log;
 
-	if (!vmap_lazy_unmap)
-		return 0;
-
 	log = fls(num_online_cpus());
 
 	return log * (32UL * 1024 * 1024 / PAGE_SIZE);
@@ -566,7 +561,6 @@ static void __purge_vmap_area_lazy(unsigned long *start, unsigned long *end,
 			if (va->va_end > *end)
 				*end = va->va_end;
 			nr += (va->va_end - va->va_start) >> PAGE_SHIFT;
-			unmap_vmap_area(va);
 			list_add_tail(&va->purge_list, &valist);
 			va->flags |= VM_LAZY_FREEING;
 			va->flags &= ~VM_LAZY_FREE;
@@ -611,10 +605,11 @@ static void purge_vmap_area_lazy(void)
 }
 
 /*
- * Free and unmap a vmap area, caller ensuring flush_cache_vunmap had been
- * called for the correct range previously.
+ * Free a vmap area, caller ensuring that the area has been unmapped
+ * and flush_cache_vunmap had been called for the correct range
+ * previously.
  */
-static void free_unmap_vmap_area_noflush(struct vmap_area *va)
+static void free_vmap_area_noflush(struct vmap_area *va)
 {
 	va->flags |= VM_LAZY_FREE;
 	atomic_add((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr);
@@ -623,6 +618,16 @@ static void free_unmap_vmap_area_noflush(struct vmap_area *va)
 }
 
 /*
+ * Free and unmap a vmap area, caller ensuring flush_cache_vunmap had been
+ * called for the correct range previously.
+ */
+static void free_unmap_vmap_area_noflush(struct vmap_area *va)
+{
+	unmap_vmap_area(va);
+	free_vmap_area_noflush(va);
+}
+
+/*
  * Free and unmap a vmap area
  */
 static void free_unmap_vmap_area(struct vmap_area *va)
@@ -798,7 +803,7 @@ static void free_vmap_block(struct vmap_block *vb)
 	spin_unlock(&vmap_block_tree_lock);
 	BUG_ON(tmp != vb);
 
-	free_unmap_vmap_area_noflush(vb->va);
+	free_vmap_area_noflush(vb->va);
 	call_rcu(&vb->rcu_head, rcu_free_vb);
 }
 
@@ -936,6 +941,8 @@ static void vb_free(const void *addr, unsigned long size)
 	rcu_read_unlock();
 	BUG_ON(!vb);
 
+	vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);
+
 	spin_lock(&vb->lock);
 	BUG_ON(bitmap_allocate_region(vb->dirty_map, offset >> PAGE_SHIFT, order));
 
@@ -988,7 +995,6 @@ void vm_unmap_aliases(void)
 
 				s = vb->va->va_start + (i << PAGE_SHIFT);
 				e = vb->va->va_start + (j << PAGE_SHIFT);
-				vunmap_page_range(s, e);
 				flush = 1;
 
 				if (s < start)