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, 41 insertions, 5 deletions

diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index a02318c6d28a..3d0a7e702c94 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -66,23 +66,59 @@ int dev_dax_kmem_probe(struct device *dev)
         new_res->name = dev_name(dev);
 
         rc = add_memory(numa_node, new_res->start, resource_size(new_res));
-        if (rc)
+        if (rc) {
+                release_resource(new_res);
+                kfree(new_res);
                 return rc;
+        }
+        dev_dax->dax_kmem_res = new_res;
 
         return 0;
 }
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static int dev_dax_kmem_remove(struct device *dev)
+{
+        struct dev_dax *dev_dax = to_dev_dax(dev);
+        struct resource *res = dev_dax->dax_kmem_res;
+        resource_size_t kmem_start = res->start;
+        resource_size_t kmem_size = resource_size(res);
+        int rc;
+
+        /*
+         * We have one shot for removing memory, if some memory blocks were not
+         * offline prior to calling this function remove_memory() will fail, and
+         * there is no way to hotremove this memory until reboot because device
+         * unbind will succeed even if we return failure.
+         */
+        rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size);
+        if (rc) {
+                dev_err(dev,
+                        "DAX region %pR cannot be hotremoved until the next reboot\n",
+                        res);
+                return rc;
+        }
+
+        /* Release and free dax resources */
+        release_resource(res);
+        kfree(res);
+        dev_dax->dax_kmem_res = NULL;
+
+        return 0;
+}
+#else
 static int dev_dax_kmem_remove(struct device *dev)
 {
         /*
-         * Purposely leak the request_mem_region() for the device-dax
-         * range and return '0' to ->remove() attempts. The removal of
-         * the device from the driver always succeeds, but the region
-         * is permanently pinned as reserved by the unreleased
+         * Without hotremove purposely leak the request_mem_region() for the
+         * device-dax range and return '0' to ->remove() attempts. The removal
+         * of the device from the driver always succeeds, but the region is
+         * permanently pinned as reserved by the unreleased
          * request_mem_region().
          */
         return 0;
 }
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 
 static struct dax_device_driver device_dax_kmem_driver = {
         .drv = {