Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753162AbbD0PUI (ORCPT ); Mon, 27 Apr 2015 11:20:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45530 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752321AbbD0PUG (ORCPT ); Mon, 27 Apr 2015 11:20:06 -0400 Date: Mon, 27 Apr 2015 17:19:46 +0200 From: Oleg Nesterov To: Bobby Powers Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Andi Kleen , Borislav Petkov , Ingo Molnar , Andy Lutomirski , Dave Hansen , Fenghua Yu , Linus Torvalds , Pekka Riikonen , Quentin Casasnovas , Rik van Riel , Suresh Siddha Subject: Re: [PATCH v2] x86/fpu: always restore_xinit_state() when use_eager_cpu() Message-ID: <20150427151946.GA28094@redhat.com> References: <20150427144931.GA25690@redhat.com> <1430147441-9820-1-git-send-email-bobbypowers@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1430147441-9820-1-git-send-email-bobbypowers@gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2526 Lines: 68 Thanks! On 04/27, Bobby Powers wrote: > > v2: switch used_math() -> tsk_used_math(tsk) to consistently use the > grabbed tsk instead of current, like in the rest of flush_thread(). > > Oleg's commit f893959b ("x86/fpu: Don't abuse drop_init_fpu() in > flush_thread()") removed drop_init_fpu() usage from flush_thread. > This seems to break things for me - the Go 1.4 test suite fails all > over the place with floating point comparision errors (offending > commit found through bisection). > > The functional change was that flush_thread after f893959b only calls > restore_init_xstate when both use_eager_fpu() and !used_math() are > true. drop_init_fpu (now fpu_reset_state) calls restore_init_xstate() > regardless of whether current used_math() - apply the same logic here. > > Fixes: f893959b ("x86/fpu: Don't abuse drop_init_fpu() in flush_thread()") > Signed-off-by: Bobby Powers > Acked-by: Oleg Nesterov > Cc: Andi Kleen > Cc: Borislav Petkov > Cc: Ingo Molnar > Cc: Andy Lutomirski > Cc: Dave Hansen > Cc: Fenghua Yu > Cc: Linus Torvalds > Cc: Pekka Riikonen > Cc: Quentin Casasnovas > Cc: Rik van Riel > Cc: Suresh Siddha > --- > arch/x86/kernel/process.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index 8213da6..1a6fcf8 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -156,11 +156,13 @@ void flush_thread(void) > /* FPU state will be reallocated lazily at the first use. */ > drop_fpu(tsk); > free_thread_xstate(tsk); > - } else if (!used_math()) { > - /* kthread execs. TODO: cleanup this horror. */ > - if (WARN_ON(init_fpu(tsk))) > - force_sig(SIGKILL, tsk); > - user_fpu_begin(); > + } else { > + if (!tsk_used_math(tsk)) { > + /* kthread execs. TODO: cleanup this horror. */ > + if (WARN_ON(init_fpu(tsk))) > + force_sig(SIGKILL, tsk); > + user_fpu_begin(); > + } > restore_init_xstate(); > } > } > -- > 2.3.6 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/