(Sorry, with proper addressing now)
On 1/27/20 6:29 PM, Boris Ostrovsky wrote:
>
>
> On 1/27/20 4:37 PM, Marek Marczykowski-Górecki wrote:
>>
>>>> Loading Linux 5.5.0-accecn30 ...
>>>>
>>>> .[5;22H [ initrd.img-5.5.0-acc 16.52MiB 100% 10.23MiB/s
>>>> ].[5;1HSetting up swapspace version 1, size = 1073737728 bytes
>>>> /dev/xvda3: clean, 852118/1294896 files, 3076785/5190907 blocks
>>>> [ 2.730931] BUG: kernel NULL pointer dereference, address:
>>>> 00000000000003b0
>>>> [ 2.730959] #PF: supervisor read access in kernel mode
>>>> [ 2.730966] #PF: error_code(0x0000) - not-present page
>>>> [ 2.730973] PGD 0 P4D 0
>>>> [ 2.730978] Oops: 0000 [#1] SMP PTI
>>>> [ 2.730985] CPU: 1 PID: 402 Comm: qubesdb-daemon Tainted: G O
>>>> 5.5.0-accecn30 #31
>>>> [ 2.731000] RIP: 0010:mmu_interval_read_begin+0x24/0xc0
>
>
>
>
> This looks like it could well be
> d3eeb1d77c5d0af9df442db63722928238310a86. Can you revert it and see if
> it makes a difference?
>
> (+Jason)
>
> -boris
>
>
>
>
>>>> [ 2.731008] Code: e9 51 66 e1 ff 90 0f 1f 44 00 00 41 54 49 89 fc 55 53
>>>> 48 83 ec 30 65 48 8b 04 25 28 00 00 00 48 89 44 24 28 31 c0 48 8b 47 38
>>>> <48> 8b a8 b0 03 00 00 48 8d 5d 0c 48 89 df e8 49 27 6f 00 4d 8b 64
>>>> [ 2.731030] RSP: 0018:ffff9873001e7d20 EFLAGS: 00010246
>>>> [ 2.731037] RAX: 0000000000000000 RBX: ffff8a4e94712500 RCX:
>>>> 0000000000000000
I am pretty sure it is.
RAX=0 most likely means that map->notifier is NULL (assuming your
compiler generates code similar to mine).
I believe you at least need
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 4fc83e3f..d35cf0b 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1016,7 +1016,8 @@ static int gntdev_mmap(struct file *flip, struct
vm_area_struct *vma)
* and we are holding it now, there is no need for the
notifier_range
* locking pattern.
*/
- mmu_interval_read_begin(&map->notifier);
+ if (use_ptemod)
+ mmu_interval_read_begin(&map->notifier);
if (use_ptemod) {
map->pages_vm_start = vma->vm_start;
and maybe more. Give that a try.
-boris
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
