linux-kernel - [PATCH 4.9 061/109] powerpc/mm: Fix memory hotplug BUG() on radix

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Message-Id: <20171207125641.806213192@linuxfoundation.org>
Date:   Thu,  7 Dec 2017 13:56:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 061/109] powerpc/mm: Fix memory hotplug BUG() on radix

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Reza Arbab <arbab@...ux.vnet.ibm.com>


[ Upstream commit 32b53c012e0bfe20b2745962a89db0dc72ef3270 ]

Memory hotplug is leading to hash page table calls, even on radix:

  arch_add_memory
    create_section_mapping
      htab_bolt_mapping
        BUG_ON(!ppc_md.hpte_insert);

To fix, refactor {create,remove}_section_mapping() into hash__ and
radix__ variants. Leave the radix versions stubbed for now.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@...il.com>
Signed-off-by: Reza Arbab <arbab@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/powerpc/include/asm/book3s/64/hash.h |    4 ++++
 arch/powerpc/mm/hash_utils_64.c           |    4 ++--
 arch/powerpc/mm/pgtable-book3s64.c        |   18 ++++++++++++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)

--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -201,6 +201,10 @@ extern int __meminit hash__vmemmap_creat
 					      unsigned long phys);
 extern void hash__vmemmap_remove_mapping(unsigned long start,
 				     unsigned long page_size);
+
+int hash__create_section_mapping(unsigned long start, unsigned long end);
+int hash__remove_section_mapping(unsigned long start, unsigned long end);
+
 #endif /* !__ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_HASH_H */
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -747,7 +747,7 @@ static unsigned long __init htab_get_tab
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-int create_section_mapping(unsigned long start, unsigned long end)
+int hash__create_section_mapping(unsigned long start, unsigned long end)
 {
 	int rc = htab_bolt_mapping(start, end, __pa(start),
 				   pgprot_val(PAGE_KERNEL), mmu_linear_psize,
@@ -761,7 +761,7 @@ int create_section_mapping(unsigned long
 	return rc;
 }
 
-int remove_section_mapping(unsigned long start, unsigned long end)
+int hash__remove_section_mapping(unsigned long start, unsigned long end)
 {
 	int rc = htab_remove_mapping(start, end, mmu_linear_psize,
 				     mmu_kernel_ssize);
--- a/arch/powerpc/mm/pgtable-book3s64.c
+++ b/arch/powerpc/mm/pgtable-book3s64.c
@@ -125,3 +125,21 @@ void mmu_cleanup_all(void)
 	else if (mmu_hash_ops.hpte_clear_all)
 		mmu_hash_ops.hpte_clear_all();
 }
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+int create_section_mapping(unsigned long start, unsigned long end)
+{
+	if (radix_enabled())
+		return -ENODEV;
+
+	return hash__create_section_mapping(start, end);
+}
+
+int remove_section_mapping(unsigned long start, unsigned long end)
+{
+	if (radix_enabled())
+		return -ENODEV;
+
+	return hash__remove_section_mapping(start, end);
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */