ARM: fix a cockup in 48be69a02 (ARM: move signal handlers into a vdso-like page)
authorRussell King <rmk+kernel@arm.linux.org.uk>
Sat, 3 Aug 2013 09:30:05 +0000 (10:30 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 12 Aug 2013 01:35:20 +0000 (18:35 -0700)
commit17ef32956a8481fba02751e14c17c648c9f472e6
tree00c310cc365a68606015400ca0927ab53e1fa8a3
parent75bc4446e0d553aceeb632ae05878786d6760e47
ARM: fix a cockup in 48be69a02 (ARM: move signal handlers into a vdso-like page)

commit e0d407564b532d978b03ceccebd224a05d02f111 upstream.

Unfortunately, I never committed the fix to a nasty oops which can
occur as a result of that commit:

------------[ cut here ]------------
kernel BUG at /home/olof/work/batch/include/linux/mm.h:414!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 490 Comm: killall5 Not tainted 3.11.0-rc3-00288-gabe0308 #53
task: e90acac0 ti: e9be8000 task.ti: e9be8000
PC is at special_mapping_fault+0xa4/0xc4
LR is at __do_fault+0x68/0x48c

This doesn't show up unless you do quite a bit of testing; a simple
boot test does not do this, so all my nightly tests were passing fine.

The reason for this is that install_special_mapping() expects the
page array to stick around, and as this was only inserting one page
which was stored on the kernel stack, that's why this was blowing up.

Reported-by: Olof Johansson <olof@lixom.net>
Tested-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/arm/kernel/process.c
arch/arm/kernel/signal.c