From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Date: Thu, 29 Dec 2005 16:39:51 +0000 (+0100)
Subject: [PATCH] uml: fix random segfaults at bootup
X-Git-Tag: v2.6.15~26
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=516949480d3700cbde4272228a102c84721d6007;p=pandora-kernel.git

[PATCH] uml: fix random segfaults at bootup

Don't use printk() where "current_thread_info()" is crap.

Until when we switch to running on init_stack, current_thread_info() evaluates
to crap. Printk uses "current" at times (in detail, &current is evaluated with
CONFIG_DEBUG_SPINLOCK to check the spinlock owner task).

And this leads to random segmentation faults.

Exactly, what happens is that &current = *(current_thread_info()), i.e. round
down $esp and dereference the value. I.e. access the stack below $esp, which
causes SIGSEGV on a VM_GROWSDOWN vma (see arch/i386/mm/fault.c).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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