From: Oleg Nesterov Date: Mon, 19 Jan 2015 18:51:32 +0000 (+0100) Subject: x86/fpu: __kernel_fpu_begin() should clear fpu_owner_task even if use_eager_fpu() X-Git-Tag: omap-for-v4.1/fixes-rc1~189^2~11^2~2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7aeccb83e76316b365e4b44a1dd982ee22a7d8b2;p=pandora-kernel.git x86/fpu: __kernel_fpu_begin() should clear fpu_owner_task even if use_eager_fpu() __kernel_fpu_begin() does nothing if !__thread_has_fpu() && use_eager_fpu(), perhaps it assumes that this case is simply impossible. This is certainly not possible if in_interrupt() == T; interrupted_user_mode() should have FPU, and interrupted_kernel_fpu_idle() should fail if !__thread_has_fpu(). However, even if use_eager_fpu() == T a task can do drop_fpu(), then switch to another thread which becomes fpu_owner_task, then resume and call some function which does kernel_fpu_begin(). Say, an exiting task does a lot of things after exit_thread(), it is not safe to assume that it can't use FPU in these paths. Signed-off-by: Oleg Nesterov Reviewed-by: Rik van Riel Cc: Linus Torvalds Cc: Suresh Siddha Cc: Andy Lutomirski Cc: Pekka Riikonen Link: http://lkml.kernel.org/r/20150119185132.GB16427@redhat.com Signed-off-by: Borislav Petkov --- Reading git-diff-tree failed