Re: 2.1.82-87: Hanging in __wait_on_page (was: Re: Hang in wait_on_inode with SMP 2.1.87) and SMP+IO

Richard Jones (rjones@orchestream.com)
Thu, 26 Feb 1998 18:31:36 +0000

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-- 
Richard Jones  rjones@orchestream.com Tel: +44 171 460 6141 Fax: .. 4461
Orchestream Ltd.  262a Fulham Rd.  London  SW10 9EL.  "you'll write in
PGP: www.four11.com     telegraphic, or you won't write at all" [Céline]
Copyright © 1998 Richard W.M. Jones
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Message-ID: <34F5B425.67ECB3D5@orchestream.com>
Date: Thu, 26 Feb 1998 18:27:49 +0000
From: Richard Jones <rjones@orchestream.com>
Organization: Orchestream Ltd.
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To: David Woodhouse <Dave@imladris.demon.co.uk>
Subject: Re: 2.1.82-87: Hanging in __wait_on_page (was: Re: Hang in wait_on_inode with SMP 2.1.87) and SMP+IO APIC+aic = bad
References: <E0y864b-00019d-00@imladris.demon.co.uk>
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David Woodhouse wrote:
> 
> fharvell@odin.magicnet.net said:
> >
> >   If anyone has any instructions on how to get more information out
> > of a stuck process, please let me know.
> 
> How about some way of forcing that process to oops?


I do have a patch to the kernel now that lets me force a
process to oops. I don't think it's possible in the standard
kernel.


The real problem is it doesn't hung very often, and in fact
it hasn't hung at all since I applied the patch below.
But I won't know for sure whether the patch has fixed
things until next week at the earliest.


Rich.



-- 
Richard Jones  rjones@orchestream.com Tel: +44 171 460 6141 Fax: .. 4461
Orchestream Ltd.  262a Fulham Rd.  London  SW10 9EL.  "you'll write in
PGP: www.four11.com     telegraphic, or you won't write at all" [Céline]
Copyright © 1998 Richard W.M. Jones
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diff -urN linux-2.1.88-unpatched/mm/filemap.c linux-2.1.88/mm/filemap.c
--- linux-2.1.88-unpatched/mm/filemap.c	Wed Feb 25 18:08:12 1998
+++ linux-2.1.88/mm/filemap.c	Mon Feb 23 10:49:45 1998
@@ -312,6 +312,7 @@
 	add_wait_queue(&page->wait, &wait);
 repeat:
 	tsk->state = TASK_UNINTERRUPTIBLE;
+	__asm__ __volatile__("cpuid": : :"ax", "bx", "cx", "dx", "memory");
 	run_task_queue(&tq_disk);
 	if (PageLocked(page)) {
 		schedule();


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