Date: Mon, 4 May 2015 10:11:20 +0200
From: Borislav Petkov <bp@suse.de>
To: Bobby Powers <bobbypowers@gmail.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
        Oleg Nesterov <oleg@redhat.com>, Andi Kleen <ak@linux.intel.com>,
        Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@amacapital.net>,
        Dave Hansen <dave.hansen@intel.com>, Fenghua Yu <fenghua.yu@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Pekka Riikonen <priikone@iki.fi>,
        Quentin Casasnovas <quentin.casasnovas@oracle.com>,
        Rik van Riel <riel@redhat.com>, Suresh Siddha <sbsiddha@gmail.com>
Subject: Re: [PATCH v2] x86/fpu: always restore_xinit_state() when
 use_eager_cpu()
Message-ID: <20150504081120.GA4096@pd.tnic>
References: <20150427144931.GA25690@redhat.com>
 <1430147441-9820-1-git-send-email-bobbypowers@gmail.com>
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On Mon, Apr 27, 2015 at 08:10:41AM -0700, 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 <bobbypowers@gmail.com>
> Acked-by: Oleg Nesterov <oleg@redhat.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Pekka Riikonen <priikone@iki.fi>
> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: Suresh Siddha <sbsiddha@gmail.com>
> ---
>  arch/x86/kernel/process.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)

Applied, thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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