[Crash-utility] mount cmd crashes crash

[Bob Montgomery]

I'm working on a dump of a system that did not have a PID 1.  I don't
think it's relevant to the crash itself, but it does cause crash get
a seg fault.

crash> ps | head
   PID    PPID  CPU       TASK        ST  %MEM     VSZ    RSS  COMM
      0      0   0  ffffffff805144c0  RU   0.0       0      0  [swapper]
      0     -1   1  ffff81012bc0a100  RU   0.0       0      0  [swapper]
      2     -1   0  ffff81012bd3c040  IN   0.0       0      0  [migration/0]
      3     -1   0  ffff81012bd3e7c0  RU   0.0       0      0  [ksoftirqd/0]
      4     -1   0  ffff81012bd3e080  IN   0.0       0      0  [watchdog/0]
      5     -1   1  ffff81012bd3f800  IN   0.0       0      0  [migration/1]
      6     -1   1  ffff81012bd3f0c0  RU   0.0       0      0  [ksoftirqd/1]
      7     -1   1  ffff81012bc0a840  IN   0.0       0      0  [watchdog/1]
      8     -1   0  ffff81012af02880  IN   0.0       0      0  [events/0]
crash> mount
Segmentation fault (core dumped)

In cmd_mount, this returns null and subsequent use causes the seg fault:

1156 
1157         namespace_context = pid_to_context(1);

I don't know if it was important to have the context of pid 1 for
reporting mounts, or just any context, but this hack makes the problem
go away, although not a very efficient way to find the lowest existing
PID above 0.  

--- filesys.c.orig	2010-08-18 14:03:26.000000000 -0600
+++ filesys.c	2010-08-18 14:10:02.000000000 -0600
@@ -1153,8 +1153,12 @@ cmd_mount(void)
 	ulong vfsmount = 0;
 	int flags = 0;
 	int save_next;
+	ulong pid;
 
-	namespace_context = pid_to_context(1);
+	/* find a context */
+	pid = 1;
+	while ((namespace_context = pid_to_context(pid)) == NULL)
+		pid++;
 
         while ((c = getopt(argcnt, args, "ifn:")) != EOF) {
                 switch(c)

Bob Montgomery
At HP




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