From: Vincent Palatin Date: Fri, 30 Nov 2012 20:15:32 +0000 (-0800) Subject: x86, fpu: Avoid FPU lazy restore after suspend X-Git-Tag: v3.7-rc8~13^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=644c154186386bb1fa6446bc5e037b9ed098db46;p=pandora-kernel.git x86, fpu: Avoid FPU lazy restore after suspend When a cpu enters S3 state, the FPU state is lost. After resuming for S3, if we try to lazy restore the FPU for a process running on the same CPU, this will result in a corrupted FPU context. Ensure that "fpu_owner_task" is properly invalided when (re-)initializing a CPU, so nobody will try to lazy restore a state which doesn't exist in the hardware. Tested with a 64-bit kernel on a 4-core Ivybridge CPU with eagerfpu=off, by doing thousands of suspend/resume cycles with 4 processes doing FPU operations running. Without the patch, a process is killed after a few hundreds cycles by a SIGFPE. Cc: Duncan Laurie Cc: Olof Johansson Cc: v3.4+ # for 3.4 need to replace this_cpu_write by percpu_write Signed-off-by: Vincent Palatin Link: http://lkml.kernel.org/r/1354306532-1014-1-git-send-email-vpalatin@chromium.org Signed-off-by: H. Peter Anvin --- Reading git-diff-tree failed