Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:
 "VM:
   - z3fold fixes and enhancements by Henry Burns and Vitaly Wool

   - more accurate reclaimed slab caches calculations by Yafang Shao

   - fix MAP_UNINITIALIZED UAPI symbol to not depend on config, by
     Christoph Hellwig

   - !CONFIG_MMU fixes by Christoph Hellwig

   - new novmcoredd parameter to omit device dumps from vmcore, by
     Kairui Song

   - new test_meminit module for testing heap and pagealloc
     initialization, by Alexander Potapenko

   - ioremap improvements for huge mappings, by Anshuman Khandual

   - generalize kprobe page fault handling, by Anshuman Khandual

   - device-dax hotplug fixes and improvements, by Pavel Tatashin

   - enable synchronous DAX fault on powerpc, by Aneesh Kumar K.V

   - add pte_devmap() support for arm64, by Robin Murphy

   - unify locked_vm accounting with a helper, by Daniel Jordan

   - several misc fixes

  core/lib:
   - new typeof_member() macro including some users, by Alexey Dobriyan

   - make BIT() and GENMASK() available in asm, by Masahiro Yamada

   - changed LIST_POISON2 on x86_64 to 0xdead000000000122 for better
     code generation, by Alexey Dobriyan

   - rbtree code size optimizations, by Michel Lespinasse

   - convert struct pid count to refcount_t, by Joel Fernandes

  get_maintainer.pl:
   - add --no-moderated switch to skip moderated ML's, by Joe Perches

  misc:
   - ptrace PTRACE_GET_SYSCALL_INFO interface

   - coda updates

   - gdb scripts, various"

[ Using merge message suggestion from Vlastimil Babka, with some editing - Linus ]

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (100 commits)
  fs/select.c: use struct_size() in kmalloc()
  mm: add account_locked_vm utility function
  arm64: mm: implement pte_devmap support
  mm: introduce ARCH_HAS_PTE_DEVMAP
  mm: clean up is_device_*_page() definitions
  mm/mmap: move common defines to mman-common.h
  mm: move MAP_SYNC to asm-generic/mman-common.h
  device-dax: "Hotremove" persistent memory that is used like normal RAM
  mm/hotplug: make remove_memory() interface usable
  device-dax: fix memory and resource leak if hotplug fails
  include/linux/lz4.h: fix spelling and copy-paste errors in documentation
  ipc/mqueue.c: only perform resource calculation if user valid
  include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures
  scripts/gdb: add helpers to find and list devices
  scripts/gdb: add lx-genpd-summary command
  drivers/pps/pps.c: clear offset flags in PPS_SETPARAMS ioctl
  kernel/pid.c: convert struct pid count to refcount_t
  drivers/rapidio/devices/rio_mport_cdev.c: NUL terminate some strings
  select: shift restore_saved_sigmask_unless() into poll_select_copy_remaining()
  select: change do_poll() to return -ERESTARTNOHAND rather than -EINTR
  ...

1 files changed, 43 insertions, 21 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6166ba5a15f3..4ebe696138e8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1734,9 +1734,10 @@ static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
 		endpa = PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1;
 		pr_warn("removing memory fails, because memory [%pa-%pa] is onlined\n",
 			&beginpa, &endpa);
-	}
 
-	return ret;
+		return -EBUSY;
+	}
+	return 0;
 }
 
 static int check_cpu_on_node(pg_data_t *pgdat)
@@ -1819,19 +1820,9 @@ static void __release_memory_resource(resource_size_t start,
 	}
 }
 
-/**
- * remove_memory
- * @nid: the node ID
- * @start: physical address of the region to remove
- * @size: size of the region to remove
- *
- * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
- * and online/offline operations before this call, as required by
- * try_offline_node().
- */
-void __ref __remove_memory(int nid, u64 start, u64 size)
+static int __ref try_remove_memory(int nid, u64 start, u64 size)
 {
-	int ret;
+	int rc = 0;
 
 	BUG_ON(check_hotplug_memory_range(start, size));
 
@@ -1839,13 +1830,13 @@ void __ref __remove_memory(int nid, u64 start, u64 size)
 
 	/*
 	 * All memory blocks must be offlined before removing memory.  Check
-	 * whether all memory blocks in question are offline and trigger a BUG()
+	 * whether all memory blocks in question are offline and return error
 	 * if this is not the case.
 	 */
-	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
-				check_memblock_offlined_cb);
-	if (ret)
-		BUG();
+	rc = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
+			       check_memblock_offlined_cb);
+	if (rc)
+		goto done;
 
 	/* remove memmap entry */
 	firmware_map_remove(start, start + size, "System RAM");
@@ -1857,14 +1848,45 @@ void __ref __remove_memory(int nid, u64 start, u64 size)
 
 	try_offline_node(nid);
 
+done:
 	mem_hotplug_done();
+	return rc;
 }
 
-void remove_memory(int nid, u64 start, u64 size)
+/**
+ * remove_memory
+ * @nid: the node ID
+ * @start: physical address of the region to remove
+ * @size: size of the region to remove
+ *
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations before this call, as required by
+ * try_offline_node().
+ */
+void __remove_memory(int nid, u64 start, u64 size)
+{
+
+	/*
+	 * trigger BUG() is some memory is not offlined prior to calling this
+	 * function
+	 */
+	if (try_remove_memory(nid, start, size))
+		BUG();
+}
+
+/*
+ * Remove memory if every memory block is offline, otherwise return -EBUSY is
+ * some memory is not offline
+ */
+int remove_memory(int nid, u64 start, u64 size)
 {
+	int rc;
+
 	lock_device_hotplug();
-	__remove_memory(nid, start, size);
+	rc  = try_remove_memory(nid, start, size);
 	unlock_device_hotplug();
+
+	return rc;
 }
 EXPORT_SYMBOL_GPL(remove_memory);
 #endif /* CONFIG_MEMORY_HOTREMOVE */