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Subject[PATCH v1 4/4] mm/memory_hotplug: Make __remove_pages() and arch_remove_memory() never fail
Date
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.

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: x86@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
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: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/ia64/mm/init.c | 11 +++--------
arch/powerpc/mm/mem.c | 11 ++++-------
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, 25 insertions(+), 41 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 76deaa8525db..cc9425fb9056 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -131,8 +131,8 @@ int __meminit arch_add_memory(int nid, u64 start, u64 size,
}

#ifdef CONFIG_MEMORY_HOTREMOVE
-int __meminit arch_remove_memory(int nid, u64 start, u64 size,
- struct vmem_altmap *altmap)
+void __meminit 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;
@@ -147,14 +147,13 @@ int __meminit 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
@@ -162,8 +161,6 @@ int __meminit arch_remove_memory(int nid, u64 start, u64 size,
vm_unmap_aliases();

resize_hpt_for_hotplug(memblock_phys_mem_size());
-
- return ret;
}
#endif
#endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index f5db961ad792..31b1071315d7 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -234,14 +234,15 @@ 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 168d3a6b9358..5aeb4d7099a1 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 d0a145ffa4fe..9d0efac902ec 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -112,10 +112,10 @@ 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 17a60281c36f..52fef4a81e4c 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -548,8 +548,8 @@ 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;
@@ -580,7 +580,6 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
}

set_zone_contiguous(zone);
- return 0;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */

--
2.17.2
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