Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:
 "155 patches.

  Subsystems affected by this patch series: mm (dax, debug, thp,
  readahead, page-poison, util, memory-hotplug, zram, cleanups), misc,
  core-kernel, get_maintainer, MAINTAINERS, lib, bitops, checkpatch,
  binfmt, ramfs, autofs, nilfs, rapidio, panic, relay, kgdb, ubsan,
  romfs, and fault-injection"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (155 commits)
  lib, uaccess: add failure injection to usercopy functions
  lib, include/linux: add usercopy failure capability
  ROMFS: support inode blocks calculation
  ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang
  sched.h: drop in_ubsan field when UBSAN is in trap mode
  scripts/gdb/tasks: add headers and improve spacing format
  scripts/gdb/proc: add struct mount & struct super_block addr in lx-mounts command
  kernel/relay.c: drop unneeded initialization
  panic: dump registers on panic_on_warn
  rapidio: fix the missed put_device() for rio_mport_add_riodev
  rapidio: fix error handling path
  nilfs2: fix some kernel-doc warnings for nilfs2
  autofs: harden ioctl table
  ramfs: fix nommu mmap with gaps in the page cache
  mm: remove the now-unnecessary mmget_still_valid() hack
  mm/gup: take mmap_lock in get_dump_page()
  binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot
  coredump: rework elf/elf_fdpic vma_dump_size() into common helper
  coredump: refactor page range dumping into common helper
  coredump: let dump_emit() bail out on short writes
  ...

1 files changed, 15 insertions, 5 deletions

diff --git a/mm/page_poison.c b/mm/page_poison.c
index 34b9181ee5d1..ae0482cded87 100644
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -8,13 +8,23 @@
 #include <linux/ratelimit.h>
 #include <linux/kasan.h>
 
-static bool want_page_poisoning __read_mostly;
+static DEFINE_STATIC_KEY_FALSE_RO(want_page_poisoning);
 
 static int __init early_page_poison_param(char *buf)
 {
-	if (!buf)
-		return -EINVAL;
-	return strtobool(buf, &want_page_poisoning);
+	int ret;
+	bool tmp;
+
+	ret = strtobool(buf, &tmp);
+	if (ret)
+		return ret;
+
+	if (tmp)
+		static_branch_enable(&want_page_poisoning);
+	else
+		static_branch_disable(&want_page_poisoning);
+
+	return 0;
 }
 early_param("page_poison", early_page_poison_param);
 
@@ -31,7 +41,7 @@ bool page_poisoning_enabled(void)
 	 * Page poisoning is debug page alloc for some arches. If
 	 * either of those options are enabled, enable poisoning.
 	 */
-	return (want_page_poisoning ||
+	return (static_branch_unlikely(&want_page_poisoning) ||
 		(!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
 		debug_pagealloc_enabled()));
 }