9.2-STABLE: supervisor read data, page not present

Konstantin Belousov kostikbel at gmail.com
Mon Sep 9 05:14:49 UTC 2013

On Sun, Sep 08, 2013 at 11:40:01PM +0200, Oliver Pinter wrote:
> #6  0xffffffff806a2ab3 in cpuctl_ioctl (dev=<value optimized out>, 
>     cmd=<value optimized out>, data=<value optimized out>, flags=0, 
>     td=<value optimized out>) at /usr/src/sys/dev/cpuctl/cpuctl.c:478
> 	cpu = <value optimized out>
> 	ret = <value optimized out>

Do you indeed posses VIA CPU ?  Was it due to some violence act ?

I am not sure about the first panic, lets fix the malloc/free corruption
and see. The proc_reap() issue might be a consequence of the memory
corruption from the wrong free().

There is no public documentation for VIA CPUs, at least I was not
able to find anything when I looked. According to the comment in the
update_via(), all what is needed is that update buffer was 4-bytes
aligned, which is always guaranteed by our malloc(9), at least for the
allocation of size >=4.

Try this.

diff --git a/sys/dev/cpuctl/cpuctl.c b/sys/dev/cpuctl/cpuctl.c
index 4e5abb2..ca5ed56 100644
--- a/sys/dev/cpuctl/cpuctl.c
+++ b/sys/dev/cpuctl/cpuctl.c
@@ -408,10 +408,10 @@ fail:
 static int
 update_via(int cpu, cpuctl_update_args_t *args, struct thread *td)
-	void *ptr = NULL;
+	void *ptr;
 	uint64_t rev0, rev1, res;
 	uint32_t tmp[4];
-	int is_bound = 0;
+	int is_bound;
 	int oldcpu;
 	int ret;
@@ -427,8 +427,7 @@ update_via(int cpu, cpuctl_update_args_t *args, struct thread *td)
 	 * 4 byte alignment required.
-	ptr = malloc(args->size + 16, M_CPUCTL, M_WAITOK);
-	ptr = (void *)(16 + ((intptr_t)ptr & ~0xf));
+	ptr = malloc(args->size, M_CPUCTL, M_WAITOK);
 	if (copyin(args->data, ptr, args->size) != 0) {
 		DPRINTF("[cpuctl,%d]: copyin %p->%p of %zd bytes failed",
 		    __LINE__, args->data, ptr, args->size);
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