mm/memory_hotplug: make __remove_pages() and arch_remove_memory() never fail

All callers of arch_remove_memory() ignore errors.  And we should really
try to remove any errors from the memory removal path.  No more errors are
reported from __remove_pages().  BUG() in s390x code in case
arch_remove_memory() is triggered.  We may implement that properly later.
WARN in case powerpc code failed to remove the section mapping, which is
better than ignoring the error completely right now.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Stefan Agner <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Arun KS <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: Mathieu Malaterre <[email protected]>
Cc: Andrew Banman <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mike Travis <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

8 files changed, 24 insertions, 40 deletions

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 379eb1f9adc9..d28e29103bdb 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -682,20 +682,15 @@ int arch_add_memory(int nid, u64 start, u64 size,
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap)
+void arch_remove_memory(int nid, u64 start, u64 size,
+			struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
-	int ret;
 
 	zone = page_zone(pfn_to_page(start_pfn));
-	ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
-	if (ret)
-		pr_warn("%s: Problem encountered in __remove_pages() as"
-			" ret=%d\n", __func__,  ret);
-
-	return ret;
+	__remove_pages(zone, start_pfn, nr_pages, altmap);
 }
 #endif
 #endif
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index de5c591a550d..e885fe2aafcc 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -131,7 +131,7 @@ int __ref arch_add_memory(int nid, u64 start, u64 size,
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int __ref arch_remove_memory(int nid, u64 start, u64 size,
+void __ref arch_remove_memory(int nid, u64 start, u64 size,
 			     struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
@@ -147,14 +147,13 @@ int __ref arch_remove_memory(int nid, u64 start, u64 size,
 	if (altmap)
 		page += vmem_altmap_offset(altmap);
 
-	ret = __remove_pages(page_zone(page), start_pfn, nr_pages, altmap);
-	if (ret)
-		return ret;
+	__remove_pages(page_zone(page), start_pfn, nr_pages, altmap);
 
 	/* Remove htab bolted mappings for this section of memory */
 	start = (unsigned long)__va(start);
 	flush_inval_dcache_range(start, start + size);
 	ret = remove_section_mapping(start, start + size);
+	WARN_ON_ONCE(ret);
 
 	/* Ensure all vmalloc mappings are flushed in case they also
 	 * hit that section of memory
@@ -163,8 +162,6 @@ int __ref arch_remove_memory(int nid, u64 start, u64 size,
 
 	if (resize_hpt_for_hotplug(memblock_phys_mem_size()) == -ENOSPC)
 		pr_warn("Hash collision while resizing HPT\n");
-
-	return ret;
 }
 #endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 06bd05137a00..14d1eae9fe43 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -237,14 +237,15 @@ int arch_add_memory(int nid, u64 start, u64 size,
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap)
+void arch_remove_memory(int nid, u64 start, u64 size,
+			struct vmem_altmap *altmap)
 {
 	/*
 	 * There is no hardware or firmware interface which could trigger a
 	 * hot memory remove on s390. So there is nothing that needs to be
 	 * implemented.
 	 */
-	return -EBUSY;
+	BUG();
 }
 #endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index d3cd07bd2dc1..b95e343e3c9d 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -429,20 +429,15 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap)
+void arch_remove_memory(int nid, u64 start, u64 size,
+			struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = PFN_DOWN(start);
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
-	int ret;
 
 	zone = page_zone(pfn_to_page(start_pfn));
-	ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
-	if (unlikely(ret))
-		pr_warn("%s: Failed, __remove_pages() == %d\n", __func__,
-			ret);
-
-	return ret;
+	__remove_pages(zone, start_pfn, nr_pages, altmap);
 }
 #endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 755dbed85531..075e568098f2 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -860,14 +860,15 @@ int arch_add_memory(int nid, u64 start, u64 size,
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap)
+void arch_remove_memory(int nid, u64 start, u64 size,
+			struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct zone *zone;
 
 	zone = page_zone(pfn_to_page(start_pfn));
-	return __remove_pages(zone, start_pfn, nr_pages, altmap);
+	__remove_pages(zone, start_pfn, nr_pages, altmap);
 }
 #endif
 #endif
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index db42c11b48fb..20d14254b686 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1141,24 +1141,20 @@ kernel_physical_mapping_remove(unsigned long start, unsigned long end)
 	remove_pagetable(start, end, true, NULL);
 }
 
-int __ref arch_remove_memory(int nid, u64 start, u64 size,
-				struct vmem_altmap *altmap)
+void __ref arch_remove_memory(int nid, u64 start, u64 size,
+			      struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
 	struct page *page = pfn_to_page(start_pfn);
 	struct zone *zone;
-	int ret;
 
 	/* With altmap the first mapped page is offset from @start */
 	if (altmap)
 		page += vmem_altmap_offset(altmap);
 	zone = page_zone(page);
-	ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
-	WARN_ON_ONCE(ret);
+	__remove_pages(zone, start_pfn, nr_pages, altmap);
 	kernel_physical_mapping_remove(start, start + size);
-
-	return ret;
 }
 #endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index b24aca54353e..ae892eef8b82 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -124,10 +124,10 @@ static inline bool movable_node_is_enabled(void)
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
-extern int arch_remove_memory(int nid, u64 start, u64 size,
-				struct vmem_altmap *altmap);
-extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
-	unsigned long nr_pages, struct vmem_altmap *altmap);
+extern void arch_remove_memory(int nid, u64 start, u64 size,
+			       struct vmem_altmap *altmap);
+extern void __remove_pages(struct zone *zone, unsigned long start_pfn,
+			   unsigned long nr_pages, struct vmem_altmap *altmap);
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 /*
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3512bba20e2b..6c0c4f48638e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -547,8 +547,8 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
  * sure that pages are marked reserved and zones are adjust properly by
  * calling offline_pages().
  */
-int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
-		 unsigned long nr_pages, struct vmem_altmap *altmap)
+void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
+		    unsigned long nr_pages, struct vmem_altmap *altmap)
 {
 	unsigned long i;
 	unsigned long map_offset = 0;
@@ -579,7 +579,6 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 	}
 
 	set_zone_contiguous(zone);
-	return 0;
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */