linux-kernel - [PATCH 1/1] x86/cpu: don't allocate fpu->state for swapper/0

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Message-ID: <20150313182716.GB8249@redhat.com>
Date:	Fri, 13 Mar 2015 19:27:16 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Dave Hansen <dave.hansen@...el.com>, Borislav Petkov <bp@...e.de>,
	Ingo Molnar <mingo@...nel.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pekka Riikonen <priikone@....fi>,
	Rik van Riel <riel@...hat.com>,
	Suresh Siddha <sbsiddha@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: [PATCH 1/1] x86/cpu: don't allocate fpu->state for swapper/0

Now that kthreads do not use FPU until exec swpper/0 doesn't need
to allocate fpu->state.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 arch/x86/kernel/xsave.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index dff0ec2..1cf5667 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -679,8 +679,6 @@ void xsave_init(void)
 
 static inline void __init eager_fpu_init_bp(void)
 {
-	current->thread.fpu.state =
-	    alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
 	if (!init_xstate_buf)
 		setup_init_fpu_buf();
 }
-- 
1.5.5.1


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