On Mon, Aug 11, 2014 at 02:25:56PM +0200, Richard Weinberger wrote:
> Hi Vivek,
>
> Am 11.08.2014 14:22, schrieb Vivek Goyal:
> > On Sun, Aug 10, 2014 at 06:56:14PM +0200, Richard Weinberger wrote:
> >> Hi Vivek,
> >>
> >> Daniel Walter reported that UML is currently broken.
> >> The offending commit is:
> >>
> >
> > Hi Richard,
> >
> > Thanks for pointing it out. I will look into it.
> >
> > Would you have link to the report Daniel sent. I am interested in
> > looking at backtrace.
>
> he reported it on IRC to me.
>
> Here is a backtrace:
> RIP: 0033:[<0000000060039b9f>]
> RSP: 0000000081459da0 EFLAGS: 00010202
> RAX: 0000000000000000 RBX: 00000000219b3fff RCX: 000000006010d1d9
> RDX: 0000000000000001 RSI: 00000000602dfb94 RDI: 0000000081459df8
> RBP: 0000000081459de0 R08: 00000000601b59f4 R09: ffffffff0000ff00
> R10: ffffffff0000ff00 R11: 0000000081459e88 R12: 0000000081459df8
> R13: 00000000219b3fff R14: 00000000602dfb94 R15: 0000000000000000
> Kernel panic - not syncing: Segfault with no mm
> CPU: 0 PID: 1 Comm: swapper Not tainted 3.16.0-10454-g58d08e3 #13
> Stack:
> 00000000 000080d0 81459df0 219b3fff
> 81459e70 6010d1d9 ffffffff 6033e010
> 81459e50 6003a269 81459e30 00000000
> Call Trace:
> [<6010d1d9>] ? kclist_add_private+0x0/0xe7
> [<6003a269>] walk_system_ram_range+0x61/0xb7
> [<6000e859>] ? proc_kcore_init+0x0/0xf1
> [<6010d574>] kcore_update_ram+0x4c/0x168
> [<6010d72e>] ? kclist_add+0x0/0x2e
> [<6000e943>] proc_kcore_init+0xea/0xf1
> [<6000e859>] ? proc_kcore_init+0x0/0xf1
> [<6000e859>] ? proc_kcore_init+0x0/0xf1
> [<600189f0>] do_one_initcall+0x13c/0x204
> [<6004ca46>] ? parse_args+0x1df/0x2e0
> [<6004c82d>] ? parameq+0x0/0x3a
> [<601b5990>] ? strcpy+0x0/0x18
> [<60001e1a>] kernel_init_freeable+0x240/0x31e
> [<6026f1c0>] kernel_init+0x12/0x148
> [<60019fad>] new_thread_handler+0x81/0xa3
>
> RIP is at kernel/resource.c:66.
Hi Richard,
Can you please give the attached patch a try and see if it fixes the UML
issue.
I noticed that previous code had a for() loop which will not execute
if p was null. I have resorted back to same code now.
Thanks
Vivek
---
kernel/resource.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
Index: linux-2.6/kernel/resource.c
===================================================================
--- linux-2.6.orig/kernel/resource.c 2014-08-11 13:36:19.942423192 -0400
+++ linux-2.6/kernel/resource.c 2014-08-11 13:50:20.529387653 -0400
@@ -351,15 +351,12 @@ static int find_next_iomem_res(struct re
end = res->end;
BUG_ON(start >= end);
- read_lock(&resource_lock);
-
- if (first_level_children_only) {
- p = iomem_resource.child;
+ if (first_level_children_only)
sibling_only = true;
- } else
- p = &iomem_resource;
- while ((p = next_resource(p, sibling_only))) {
+ read_lock(&resource_lock);
+
+ for (p = iomem_resource.child; p; p = next_resource(p, sibling_only)) {
if (p->flags != res->flags)
continue;
if (name && strcmp(p->name, name))
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