[PATCH for 4.19-stable 13/25] mm/memory_hotplug: make __remove_pages() and arch_remove_memory() never fail

[David Hildenbrand <david@redhat.com>]

commit ac5c94264580f498e484c854031d0226b3c1038f upstream.

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/20190409100148.24703-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/ia64/mm/init.c            | 11 +++--------
 arch/powerpc/mm/mem.c          |  9 +++------
 arch/s390/mm/init.c            |  5 +++--
 arch/sh/mm/init.c              | 11 +++--------
 arch/x86/mm/init_32.c          |  5 +++--
 arch/x86/mm/init_64.c          | 10 +++-------
 include/linux/memory_hotplug.h |  8 ++++----
 mm/memory_hotplug.c            |  5 ++---
 8 files changed, 24 insertions(+), 40 deletions(-)

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index b54d0ee74b53..950a9e0a4548 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -662,20 +662,15 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
 }
 
 #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 e27e5bc958b4..d3fd0095aae6 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -140,7 +140,7 @@ int __ref arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altm
 }
 
 #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;
@@ -156,14 +156,13 @@ 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
@@ -172,8 +171,6 @@ 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 bc49b560625e..0da486d914e4 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -240,14 +240,15 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
 }
 
 #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 5c91bb6abc35..59ae5d7dc081 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -444,20 +444,15 @@ 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 9fa503f2f56c..c6a50a0f240b 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -861,14 +861,15 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
 }
 
 #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 32066d5dc9af..b9e15f25b921 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1142,24 +1142,20 @@ 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 df77a7597aba..04c40da0228a 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -109,10 +109,10 @@ 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 */
 
 /* reasonably generic interface to expand the physical pages */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a9fcae50a33a..7905e3275289 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -509,8 +509,8 @@ 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;
@@ -541,7 +541,6 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 	}
 
 	set_zone_contiguous(zone);
-	return 0;
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
-- 
2.24.1