linux-kernel - Re: [RFC] : Is /proc/kcore still usefull and/or maintained ?

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Date:	Thu, 22 Mar 2007 00:53:10 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Maxim <maximlevitsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Jan Engelhardt <jengelh@...ux01.gwdg.de>, Andi Kleen <ak@...e.de>,
	David Howells <dhowells@...hat.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] : Is /proc/kcore still usefull and/or maintained ?

I stand corrected : This is a new bug

The /proc/kcore problem appears with linux-2.6.21-rc4-mm1

fd = open("/proc/kcore", 0);
llseek(fd, ...) returns an -EINVAL error


Quick code inspection (before going to sleep...) shows that

proc_reg_llseek() (file fs/proc/inode.c)

is doing something like :

rv = -EINVAL;
llseek = pde->proc_fops->llseek;
spin_unlock(&pde->pde_unload_lock);
if (llseek)
	rv = llseek(file, offset, whence);

As kcore dont have a .llseek handler, proc_reg_llseek() returns -EINVAL;

Previous kernel was probably calling a default llseek() handler.

if (!llseek)
	llseek = default_llseek;

Hum ???
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