Re: Alpha "process table hang"

[Bob McElrath <mcelrath+linux@draal.physics.wisc.edu>]

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Well, here's the list of modules I have loaded:

nfsd                  102496   8 (autoclean)
lockd                  72976   1 (autoclean) [nfsd]
sunrpc                 87984   1 (autoclean) [nfsd lockd]
nls_iso8859-1           4160   1 (autoclean)
nls_cp437               5664   1 (autoclean)
msdos                   7728   1 (autoclean)
fat                    42784   0 (autoclean) [msdos]
pas2                   17488   1
sound                  83184   1 [pas2]
soundcore               5568   5 [sound]

Are there any known problems with these?  I have at times also used
matroxfb, and usb-uhci (along with visor, usb-storage), but I've seen
the process-table-hang with matroxfb and usb-uhci *not* installed, so I
don't think that's it.  I have the above modules installed consistently
at each bootup.

Der Herr Hofrat [der.herr@hofr.at] wrote:
> > I've been experiencing a particular kind of hang for many versions
> > (since 2.3.99 days, recently seen with 2.4.1, 2.4.2, and 2.4.2-ac4) on
> > the alpha architecture.  The symptom is that any program that tries to
> > access the process table will hang. (ps, w, top) The hang will go away
> > by itself after ~10minutes - 1 hour or so.  When it hangs I run ps and
> > see that it gets halfway through the process list and hangs.  The
> > process that comes next in the list (after hang goes away) almost always
> > has nonsensical memory numbers, like multi-gigabyte SIZE.
> > 
> >
> I know this effect independant of the platform when you have a proc entry that
> is not corectly unregistered.
> 
> (the code only compiles for 2.2.X, for 2.4.X you need to change 
> the proc struct.)
> 
> ---snip---
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/proc_fs.h>
> 
> #define BUF_LEN 1024
> struct proc_dir_entry prockill_proc_file={
> 	0,
> 	0,
> 	"prockill",
> 	S_IFREG|S_IRUGO,
> 	1,
> 	0,
> 	0,
> 	BUF_LEN,
> 	NULL,
> 	NULL,
> 	NULL,	
> 	};	
> 
> int init_module(void) {
> 	printk("prockill.o registering proc entry\n");
> 	return proc_register(&proc_root,&prockill_proc_file);
> }
> 
> void cleanup_module(void) {
> 	printk("prockill.o fogets to unregister proc entry\n");
> }
> ---snip---
> compile this as kernel module
> 
> insmod proc_kill.o
> rmmod proc_kill
> 
> and the system will run without error until you do something like
> 
> ls /proc/<TAB><TAB>    or 
> ls -R /proc
> 
> after this the system will drop dead for minutes to hours or even for good....
>  
> 
> any chance you have a faulty module ??
> 
> 
> hofrat
-- Bob

Bob McElrath (rsmcelrath@students.wisc.edu) 
Univ. of Wisconsin at Madison, Department of Physics

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