powerpc/mm: Clean up memory hotplug failure paths

This makes a number of cleanups to handling of mapping failures during
memory hotplug on Power:

For errors creating the linear mapping for the hot-added region:
  * This is now reported with EFAULT which is more appropriate than the
    previous EINVAL (the failure is unlikely to be related to the
    function's parameters)
  * An error in this path now prints a warning message, rather than just
    silently failing to add the extra memory.
  * Previously a failure here could result in the region being partially
    mapped.  We now clean up any partial mapping before failing.

For errors creating the vmemmap for the hot-added region:
   * This is now reported with EFAULT instead of causing a BUG() - this
     could happen for external reason (e.g. full hash table) so it's better
     to handle this non-fatally
   * An error message is also printed, so the failure won't be silent
   * As above a failure could cause a partially mapped region, we now
     clean this up. [mpe: move htab_remove_mapping() out of #ifdef
     CONFIG_MEMORY_HOTPLUG to enable this]

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Paul Mackerras <paulus@samba.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 44f145a..335cd41 100644 (file)
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -263,7 +263,6 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
        return ret < 0 ? ret : 0;
 }
 
-#ifdef CONFIG_MEMORY_HOTPLUG
 int htab_remove_mapping(unsigned long vstart, unsigned long vend,
                      int psize, int ssize)
 {
@@ -290,7 +289,6 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 
        return ret;
 }
-#endif /* CONFIG_MEMORY_HOTPLUG */
 
 static int __init htab_dt_scan_seg_sizes(unsigned long node,
                                         const char *uname, int depth,
@@ -640,9 +638,16 @@ static unsigned long __init htab_get_table_size(void)
 #ifdef CONFIG_MEMORY_HOTPLUG
 int create_section_mapping(unsigned long start, unsigned long end)
 {
-       return htab_bolt_mapping(start, end, __pa(start),
-                                pgprot_val(PAGE_KERNEL), mmu_linear_psize,
-                                mmu_kernel_ssize);
+       int rc = htab_bolt_mapping(start, end, __pa(start),
+                                  pgprot_val(PAGE_KERNEL), mmu_linear_psize,
+                                  mmu_kernel_ssize);
+
+       if (rc < 0) {
+               int rc2 = htab_remove_mapping(start, end, mmu_linear_psize,
+                                             mmu_kernel_ssize);
+               BUG_ON(rc2 && (rc2 != -ENOENT));
+       }
+       return rc;
 }
 
 int remove_section_mapping(unsigned long start, unsigned long end)

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index baa1a23..fbc9448 100644 (file)
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -188,9 +188,9 @@ static int __meminit vmemmap_populated(unsigned long start, int page_size)
  */
 
 #ifdef CONFIG_PPC_BOOK3E
-static void __meminit vmemmap_create_mapping(unsigned long start,
-                                            unsigned long page_size,
-                                            unsigned long phys)
+static int __meminit vmemmap_create_mapping(unsigned long start,
+                                           unsigned long page_size,
+                                           unsigned long phys)
 {
        /* Create a PTE encoding without page size */
        unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
@@ -208,6 +208,8 @@ static void __meminit vmemmap_create_mapping(unsigned long start,
         */
        for (i = 0; i < page_size; i += PAGE_SIZE)
                BUG_ON(map_kernel_page(start + i, phys, flags));
+
+       return 0;
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -217,15 +219,20 @@ static void vmemmap_remove_mapping(unsigned long start,
 }
 #endif
 #else /* CONFIG_PPC_BOOK3E */
-static void __meminit vmemmap_create_mapping(unsigned long start,
-                                            unsigned long page_size,
-                                            unsigned long phys)
+static int __meminit vmemmap_create_mapping(unsigned long start,
+                                           unsigned long page_size,
+                                           unsigned long phys)
 {
-       int  mapped = htab_bolt_mapping(start, start + page_size, phys,
-                                       pgprot_val(PAGE_KERNEL),
-                                       mmu_vmemmap_psize,
-                                       mmu_kernel_ssize);
-       BUG_ON(mapped < 0);
+       int rc = htab_bolt_mapping(start, start + page_size, phys,
+                                  pgprot_val(PAGE_KERNEL),
+                                  mmu_vmemmap_psize, mmu_kernel_ssize);
+       if (rc < 0) {
+               int rc2 = htab_remove_mapping(start, start + page_size,
+                                             mmu_vmemmap_psize,
+                                             mmu_kernel_ssize);
+               BUG_ON(rc2 && (rc2 != -ENOENT));
+       }
+       return rc;
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -304,6 +311,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 
        for (; start < end; start += page_size) {
                void *p;
+               int rc;
 
                if (vmemmap_populated(start, page_size))
                        continue;
@@ -317,7 +325,13 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
                pr_debug("      * %016lx..%016lx allocated at %p\n",
                         start, start + page_size, p);
 
-               vmemmap_create_mapping(start, page_size, __pa(p));
+               rc = vmemmap_create_mapping(start, page_size, __pa(p));
+               if (rc < 0) {
+                       pr_warning(
+                               "vmemmap_populate: Unable to create vmemmap mapping: %d\n",
+                               rc);
+                       return -EFAULT;
+               }
        }
 
        return 0;

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index d0f0a51..f980da6 100644 (file)
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -119,12 +119,18 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
        struct zone *zone;
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
+       int rc;
 
        pgdata = NODE_DATA(nid);
 
        start = (unsigned long)__va(start);
-       if (create_section_mapping(start, start + size))
-               return -EINVAL;
+       rc = create_section_mapping(start, start + size);
+       if (rc) {
+               pr_warning(
+                       "Unable to create mapping for hot added memory 0x%llx..0x%llx: %d\n",
+                       start, start + size, rc);
+               return -EFAULT;
+       }
 
        /* this should work for most non-highmem platforms */
        zone = pgdata->node_zones +