Bug 6766

Summary:	read(0,..) after fork() can cause the system to hang
Product:	IO/Storage	Reporter:	Yair (irush)
Component:	Other	Assignee:	io_other
Status:	REJECTED UNREPRODUCIBLE
Severity:	normal	CC:	akpm
Priority:	P2
Hardware:	i386
OS:	Linux
Kernel Version:	2.6.17	Subsystem:
Regression:	---	Bisected commit-id:
Attachments:	causes system hang config file

Description Yair 2006-06-29 07:20:58 UTC

Most recent kernel where this bug did not occur: 2.6.14
Distribution: debian testing (vanilla kernel)
Hardware Environment: N/A
Software Environment:
Problem Description:
After forking, if the child process calls read(0,...), and then the parent
exits, the child might not respond to KILL signal and stay opened consuming more
and more resourses, eventually freezing the system which forces a reboot.

This happens in about 1 out of 7 runs (in average).
Tested on several hardwares.

Steps to reproduce:
Attached c code.

Comment 1 Yair 2006-06-29 07:29:58 UTC

Created attachment 8453 [details]
causes system hang

Comment 2 Andrew Morton 2006-06-29 14:09:54 UTC

I'm unable to reproduce this.

Some system info and a copy of your .config might help.

Comment 3 Yair 2006-07-02 05:06:58 UTC

Created attachment 8474 [details]
config file

Comment 4 Andrew Morton 2007-01-31 01:10:52 UTC

Is this problem still present in 2.6.20-rc7?

It's rather weird.

Comment 5 Yair 2007-02-01 07:03:13 UTC

As I recall, after updating some nfs utilities, the problem was gone.
Currently (2.6.19), I didn't succeed in reproducing it.

Comment 6 Andrew Morton 2007-02-01 09:04:42 UTC

OK, thanks - I'll close the bug off, mark it unreproducible.