Merge branch 'akpm' (patches from Andrew)

Merge yet more updates from Andrew Morton:
 "This is everything else from -mm for this merge window.

  90 patches.

  Subsystems affected by this patch series: mm (cleanups and slub),
  alpha, procfs, sysctl, misc, core-kernel, bitmap, lib, compat,
  checkpatch, epoll, isofs, nilfs2, hpfs, exit, fork, kexec, gcov,
  panic, delayacct, gdb, resource, selftests, async, initramfs, ipc,
  drivers/char, and spelling"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (90 commits)
  mm: fix typos in comments
  mm: fix typos in comments
  treewide: remove editor modelines and cruft
  ipc/sem.c: spelling fix
  fs: fat: fix spelling typo of values
  kernel/sys.c: fix typo
  kernel/up.c: fix typo
  kernel/user_namespace.c: fix typos
  kernel/umh.c: fix some spelling mistakes
  include/linux/pgtable.h: few spelling fixes
  mm/slab.c: fix spelling mistake "disired" -> "desired"
  scripts/spelling.txt: add "overflw"
  scripts/spelling.txt: Add "diabled" typo
  scripts/spelling.txt: add "overlfow"
  arm: print alloc free paths for address in registers
  mm/vmalloc: remove vwrite()
  mm: remove xlate_dev_kmem_ptr()
  drivers/char: remove /dev/kmem for good
  mm: fix some typos and code style problems
  ipc/sem.c: mundane typo fixes
  ...

7 files changed, 169 insertions, 4 deletions

diff --git a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
index ad7fabd575f9..65ede506305c 100644
--- a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
+++ b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
@@ -3449,4 +3449,48 @@ TEST(epoll63)
 	close(sfd[1]);
 }
 
+/*
+ *        t0    t1
+ *     (ew) \  / (ew)
+ *           e0
+ *            | (lt)
+ *           s0
+ */
+TEST(epoll64)
+{
+	pthread_t waiter[2];
+	struct epoll_event e;
+	struct epoll_mtcontext ctx = { 0 };
+
+	signal(SIGUSR1, signal_handler);
+
+	ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, ctx.sfd), 0);
+
+	ctx.efd[0] = epoll_create(1);
+	ASSERT_GE(ctx.efd[0], 0);
+
+	e.events = EPOLLIN;
+	ASSERT_EQ(epoll_ctl(ctx.efd[0], EPOLL_CTL_ADD, ctx.sfd[0], &e), 0);
+
+	/*
+	 * main will act as the emitter once both waiter threads are
+	 * blocked and expects to both be awoken upon the ready event.
+	 */
+	ctx.main = pthread_self();
+	ASSERT_EQ(pthread_create(&waiter[0], NULL, waiter_entry1a, &ctx), 0);
+	ASSERT_EQ(pthread_create(&waiter[1], NULL, waiter_entry1a, &ctx), 0);
+
+	usleep(100000);
+	ASSERT_EQ(write(ctx.sfd[1], "w", 1), 1);
+
+	ASSERT_EQ(pthread_join(waiter[0], NULL), 0);
+	ASSERT_EQ(pthread_join(waiter[1], NULL), 0);
+
+	EXPECT_EQ(ctx.count, 2);
+
+	close(ctx.efd[0]);
+	close(ctx.sfd[0]);
+	close(ctx.sfd[1]);
+}
+
 TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/kvm/lib/sparsebit.c b/tools/testing/selftests/kvm/lib/sparsebit.c
index 031ba3c932ed..a0d0c83d83de 100644
--- a/tools/testing/selftests/kvm/lib/sparsebit.c
+++ b/tools/testing/selftests/kvm/lib/sparsebit.c
@@ -1890,7 +1890,6 @@ void sparsebit_validate_internal(struct sparsebit *s)
  */
 
 #include <stdlib.h>
-#include <assert.h>
 
 struct range {
 	sparsebit_idx_t first, last;
diff --git a/tools/testing/selftests/mincore/mincore_selftest.c b/tools/testing/selftests/mincore/mincore_selftest.c
index 5a1e85ff5d32..e54106643337 100644
--- a/tools/testing/selftests/mincore/mincore_selftest.c
+++ b/tools/testing/selftests/mincore/mincore_selftest.c
@@ -14,7 +14,6 @@
 #include <sys/mman.h>
 #include <string.h>
 #include <fcntl.h>
-#include <string.h>
 
 #include "../kselftest.h"
 #include "../kselftest_harness.h"
diff --git a/tools/testing/selftests/powerpc/mm/tlbie_test.c b/tools/testing/selftests/powerpc/mm/tlbie_test.c
index f85a0938ab25..48344a74b212 100644
--- a/tools/testing/selftests/powerpc/mm/tlbie_test.c
+++ b/tools/testing/selftests/powerpc/mm/tlbie_test.c
@@ -33,7 +33,6 @@
 #include <sched.h>
 #include <time.h>
 #include <stdarg.h>
-#include <sched.h>
 #include <pthread.h>
 #include <signal.h>
 #include <sys/prctl.h>
diff --git a/tools/testing/selftests/proc/Makefile b/tools/testing/selftests/proc/Makefile
index 8be8a03d2973..1054e40a499a 100644
--- a/tools/testing/selftests/proc/Makefile
+++ b/tools/testing/selftests/proc/Makefile
@@ -12,6 +12,7 @@ TEST_GEN_PROGS += proc-self-map-files-001
 TEST_GEN_PROGS += proc-self-map-files-002
 TEST_GEN_PROGS += proc-self-syscall
 TEST_GEN_PROGS += proc-self-wchan
+TEST_GEN_PROGS += proc-subset-pid
 TEST_GEN_PROGS += proc-uptime-001
 TEST_GEN_PROGS += proc-uptime-002
 TEST_GEN_PROGS += read
diff --git a/tools/testing/selftests/proc/proc-subset-pid.c b/tools/testing/selftests/proc/proc-subset-pid.c
new file mode 100644
index 000000000000..d1052bcab039
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-subset-pid.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2021 Alexey Dobriyan <adobriyan@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+/*
+ * Test that "mount -t proc -o subset=pid" hides everything but pids,
+ * /proc/self and /proc/thread-self.
+ */
+#undef NDEBUG
+#include <assert.h>
+#include <errno.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <stdio.h>
+
+static inline bool streq(const char *a, const char *b)
+{
+	return strcmp(a, b) == 0;
+}
+
+static void make_private_proc(void)
+{
+	if (unshare(CLONE_NEWNS) == -1) {
+		if (errno == ENOSYS || errno == EPERM) {
+			exit(4);
+		}
+		exit(1);
+	}
+	if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
+		exit(1);
+	}
+	if (mount(NULL, "/proc", "proc", 0, "subset=pid") == -1) {
+		exit(1);
+	}
+}
+
+static bool string_is_pid(const char *s)
+{
+	while (1) {
+		switch (*s++) {
+		case '0':case '1':case '2':case '3':case '4':
+		case '5':case '6':case '7':case '8':case '9':
+			continue;
+
+		case '\0':
+			return true;
+
+		default:
+			return false;
+		}
+	}
+}
+
+int main(void)
+{
+	make_private_proc();
+
+	DIR *d = opendir("/proc");
+	assert(d);
+
+	struct dirent *de;
+
+	bool dot = false;
+	bool dot_dot = false;
+	bool self = false;
+	bool thread_self = false;
+
+	while ((de = readdir(d))) {
+		if (streq(de->d_name, ".")) {
+			assert(!dot);
+			dot = true;
+			assert(de->d_type == DT_DIR);
+		} else if (streq(de->d_name, "..")) {
+			assert(!dot_dot);
+			dot_dot = true;
+			assert(de->d_type == DT_DIR);
+		} else if (streq(de->d_name, "self")) {
+			assert(!self);
+			self = true;
+			assert(de->d_type == DT_LNK);
+		} else if (streq(de->d_name, "thread-self")) {
+			assert(!thread_self);
+			thread_self = true;
+			assert(de->d_type == DT_LNK);
+		} else {
+			if (!string_is_pid(de->d_name)) {
+				fprintf(stderr, "d_name '%s'\n", de->d_name);
+				assert(0);
+			}
+			assert(de->d_type == DT_DIR);
+		}
+	}
+
+	char c;
+	int rv = readlink("/proc/cpuinfo", &c, 1);
+	assert(rv == -1 && errno == ENOENT);
+
+	int fd = open("/proc/cpuinfo", O_RDONLY);
+	assert(fd == -1 && errno == ENOENT);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/proc/read.c b/tools/testing/selftests/proc/read.c
index b3ef9e14d6cc..35ee78dff144 100644
--- a/tools/testing/selftests/proc/read.c
+++ b/tools/testing/selftests/proc/read.c
@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 // Test
-// 1) read of every file in /proc
+// 1) read and lseek on every file in /proc
 // 2) readlink of every symlink in /proc
 // 3) recursively (1) + (2) for every directory in /proc
 // 4) write to /proc/*/clear_refs and /proc/*/task/*/clear_refs
@@ -45,6 +45,8 @@ static void f_reg(DIR *d, const char *filename)
 	fd = openat(dirfd(d), filename, O_RDONLY|O_NONBLOCK);
 	if (fd == -1)
 		return;
+	/* struct proc_ops::proc_lseek is mandatory if file is seekable. */
+	(void)lseek(fd, 0, SEEK_SET);
 	rv = read(fd, buf, sizeof(buf));
 	assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
 	close(fd);