he subsequent calculation of

	dtime = cputime_sub(time, tsk->acct_timexpd);

will be negative and the division performed by

	cputime_to_jiffies(dtime)

will generate an exception since the result won't fit into a 32 bit
register.

In order to fix this just always disable interrupts while accessing any
of the accounting values.

Reported by: Frans Pop <elendil@planet.nl>
Tested by: Frans Pop <elendil@planet.nl>
Cc: stable@kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
óÓ`kš