Date: Fri, 18 Apr 1997 19:10:03 -0700 (PDT) From: Tor Egge <Tor.Egge@idi.ntnu.no> To: freebsd-bugs Subject: Re: kern/3327: using gdb may cause hanging processes. Message-ID: <199704190210.TAA20562@freefall.freebsd.org>
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The following reply was made to PR kern/3327; it has been noted by GNATS.
From: Tor Egge <Tor.Egge@idi.ntnu.no>
To: Tor.Egge@idi.ntnu.no
Cc: FreeBSD-gnats-submit@freebsd.org
Subject: Re: kern/3327: using gdb may cause hanging processes.
Date: Sat, 19 Apr 1997 04:05:00 +0200
> When debugging a process, gdb sometimes gives a message of
> the form
>
> Cannot insert breakpoint 2:
> Error accessing memory address 0x25240: Bad address.
>
> After this, the process is stuck.
A more complete fix:
Allow fallback to backing objects when reading.
Unlock the vm map if vm_page_lookup fails.
Index: procfs_mem.c
===================================================================
RCS file: /home/ncvs/src/sys/miscfs/procfs/procfs_mem.c,v
retrieving revision 1.24
diff -c -r1.24 procfs_mem.c
*** procfs_mem.c 1997/04/06 02:29:31 1.24
--- procfs_mem.c 1997/04/19 01:49:07
***************
*** 197,202 ****
--- 197,213 ----
}
m = vm_page_lookup(object, pindex);
+
+ /* Allow fallback to backing objects if we are reading */
+
+ while (m == NULL && !writing && object->backing_object) {
+
+ pindex += OFF_TO_IDX(object->backing_object_offset);
+ object = object->backing_object;
+
+ m = vm_page_lookup(object, pindex);
+ }
+
if (m == NULL) {
error = EFAULT;
***************
*** 205,210 ****
--- 216,223 ----
* an error return on vm_map_lookup.
*/
object = NULL;
+
+ vm_map_lookup_done(tmap, out_entry);
break;
}
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