linux-kernel - [PATCH 3.16 040/114] s390/hugetlb: add hugepages

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Message-ID: <lsq.1465842997.622849819@decadent.org.uk>
Date:	Mon, 13 Jun 2016 19:36:37 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Martin Schwidefsky" <schwidefsky@...ibm.com>,
	"Gerald Schaefer" <gerald.schaefer@...ibm.com>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Heiko Carstens" <heiko.carstens@...ibm.com>,
	"Dominik Dingel" <dingel@...ux.vnet.ibm.com>,
	"Christian Borntraeger" <borntraeger@...ibm.com>,
	"Michael Holzheu" <holzheu@...ux.vnet.ibm.com>
Subject: [PATCH 3.16 040/114] s390/hugetlb: add hugepages_supported define

3.16.36-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dominik Dingel <dingel@...ux.vnet.ibm.com>

commit 7f9be77555bb2e52de84e9dddf7b4eb20cc6e171 upstream.

On s390 we only can enable hugepages if the underlying hardware/hypervisor
also does support this.  Common code now would assume this to be
signaled by setting HPAGE_SHIFT to 0.  But on s390, where we only
support one hugepage size, there is a link between HPAGE_SHIFT and
pageblock_order.

So instead of setting HPAGE_SHIFT to 0, we will implement the check for
the hardware capability.

Signed-off-by: Dominik Dingel <dingel@...ux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Christian Borntraeger <borntraeger@...ibm.com>
Cc: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@...ibm.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/s390/include/asm/hugetlb.h | 1 +
 1 file changed, 1 insertion(+)

--- a/arch/s390/include/asm/hugetlb.h
+++ b/arch/s390/include/asm/hugetlb.h
@@ -14,6 +14,7 @@
 
 #define is_hugepage_only_range(mm, addr, len)	0
 #define hugetlb_free_pgd_range			free_pgd_range
+#define hugepages_supported()			(MACHINE_HAS_HPAGE)
 
 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 		     pte_t *ptep, pte_t pte);