Re: [Xen-devel] Re: 2.6.37-rc1 mainline domU - BUG: unable to handle kernel paging request

[Bruce Edge <bruce.edge@xxxxxxxxx>]

On Wed, Dec 1, 2010 at 10:33 PM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

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?

mainline
 

>  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.

After testing the mainline .37 I also tried xen/next-2.6.37 with the same result. At least, I still hit a BUG after accessing an NFS mount. I didn't compare the stack, but the BUG condition looked the same.
I'll reconfirm the location and traceback of the xen/next kernel.

-Bruce

 

   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)

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