diff --git a/adb/daemon/remount_service.cpp b/adb/daemon/remount_service.cpp
index 7999ddc..ce494ee 100644
--- a/adb/daemon/remount_service.cpp
+++ b/adb/daemon/remount_service.cpp
@@ -27,68 +27,62 @@
 #include "adb_io.h"
 #include "adb_unique_fd.h"
 
-void remount_service(unique_fd fd, const std::string& cmd) {
-    static constexpr char remount_cmd[] = "/system/bin/remount";
-    static constexpr char remount_failed[] = "remount failed\n";
+static constexpr char kRemountCmd[] = "/system/bin/remount";
 
+static bool do_remount(int fd, const std::string& cmd) {
     if (getuid() != 0) {
-        WriteFdExactly(fd.get(), "Not running as root. Try \"adb root\" first.\n");
-        WriteFdExactly(fd.get(), remount_failed);
-        return;
+        WriteFdExactly(fd, "Not running as root. Try \"adb root\" first.\n");
+        return false;
     }
 
-    auto pid = vfork();
+    auto pid = fork();
     if (pid < 0) {
-        WriteFdFmt(fd.get(), "Failed to fork to %s: %s\n", remount_cmd, strerror(errno));
-        WriteFdExactly(fd.get(), remount_failed);
-        return;
+        WriteFdFmt(fd, "Failed to fork to %s: %s\n", kRemountCmd, strerror(errno));
+        return false;
     }
 
     if (pid == 0) {
         // child side of the fork
-        fcntl(fd.get(), F_SETFD, 0);
-        dup2(fd.get(), STDIN_FILENO);
-        dup2(fd.get(), STDOUT_FILENO);
-        dup2(fd.get(), STDERR_FILENO);
+        dup2(fd, STDIN_FILENO);
+        dup2(fd, STDOUT_FILENO);
+        dup2(fd, STDERR_FILENO);
 
-        execl(remount_cmd, remount_cmd, cmd.empty() ? nullptr : cmd.c_str(), nullptr);
-        _exit(-errno ?: 42);
+        execl(kRemountCmd, kRemountCmd, cmd.empty() ? nullptr : cmd.c_str(), nullptr);
+        _exit(errno);
     }
 
     int wstatus = 0;
     auto ret = waitpid(pid, &wstatus, 0);
 
     if (ret == -1) {
-        WriteFdFmt(fd.get(), "Failed to wait for %s: %s\n", remount_cmd, strerror(errno));
-        goto err;
-    }
-
-    if (ret != pid) {
-        WriteFdFmt(fd.get(), "pid %d and waitpid return %d do not match for %s\n",
-                   static_cast<int>(pid), static_cast<int>(ret), remount_cmd);
-        goto err;
+        WriteFdFmt(fd, "Failed to wait for %s: %s\n", kRemountCmd, strerror(errno));
+        return false;
+    } else if (ret != pid) {
+        WriteFdFmt(fd, "pid %d and waitpid return %d do not match for %s\n",
+                   static_cast<int>(pid), static_cast<int>(ret), kRemountCmd);
+        return false;
     }
 
     if (WIFSIGNALED(wstatus)) {
-        WriteFdFmt(fd.get(), "%s terminated with signal %s\n", remount_cmd,
+        WriteFdFmt(fd, "%s terminated with signal %s\n", kRemountCmd,
                    strsignal(WTERMSIG(wstatus)));
-        goto err;
+        return false;
     }
 
     if (!WIFEXITED(wstatus)) {
-        WriteFdFmt(fd.get(), "%s stopped with status 0x%x\n", remount_cmd, wstatus);
-        goto err;
+        WriteFdFmt(fd, "%s stopped with status 0x%x\n", kRemountCmd, wstatus);
+        return false;
     }
 
     if (WEXITSTATUS(wstatus)) {
-        WriteFdFmt(fd.get(), "%s exited with status %d\n", remount_cmd,
-                   static_cast<signed char>(WEXITSTATUS(wstatus)));
-        goto err;
+        WriteFdFmt(fd, "%s exited with status %d\n", kRemountCmd, WEXITSTATUS(wstatus));
+        return false;
     }
 
-    WriteFdExactly(fd.get(), "remount succeeded\n");
-    return;
+    return true;
+}
 
-err:
-    WriteFdExactly(fd.get(), remount_failed);
+void remount_service(unique_fd fd, const std::string& cmd) {
+    const char* success = do_remount(fd.get(), cmd) ? "succeeded" : "failed";
+    WriteFdFmt(fd.get(), "remount %s\n", success);
 }
diff --git a/adb/daemon/set_verity_enable_state_service.cpp b/adb/daemon/set_verity_enable_state_service.cpp
index 658261e..889229f 100644
--- a/adb/daemon/set_verity_enable_state_service.cpp
+++ b/adb/daemon/set_verity_enable_state_service.cpp
@@ -52,14 +52,13 @@
 }
 
 static bool make_block_device_writable(const std::string& dev) {
-    int fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
+    unique_fd fd(unix_open(dev, O_RDONLY | O_CLOEXEC));
     if (fd == -1) {
         return false;
     }
 
     int OFF = 0;
     bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
-    unix_close(fd);
     return result;
 }
 
diff --git a/fs_mgr/fs_mgr_remount.cpp b/fs_mgr/fs_mgr_remount.cpp
index 6312734..5c4008c 100644
--- a/fs_mgr/fs_mgr_remount.cpp
+++ b/fs_mgr/fs_mgr_remount.cpp
@@ -263,35 +263,43 @@
 
     // Check verity and optionally setup overlayfs backing.
     auto reboot_later = false;
+    auto uses_overlayfs = fs_mgr_overlayfs_valid() != OverlayfsValidResult::kNotSupported;
     for (auto it = partitions.begin(); it != partitions.end();) {
         auto& entry = *it;
         auto& mount_point = entry.mount_point;
         if (fs_mgr_is_verity_enabled(entry)) {
-            LOG(WARNING) << "Verity enabled on " << mount_point;
-            if (can_reboot &&
-                (android::base::GetProperty("ro.boot.vbmeta.devices_state", "") != "locked")) {
+            retval = VERITY_PARTITION;
+            if (android::base::GetProperty("ro.boot.vbmeta.devices_state", "") != "locked") {
                 if (AvbOps* ops = avb_ops_user_new()) {
                     auto ret = avb_user_verity_set(
                             ops, android::base::GetProperty("ro.boot.slot_suffix", "").c_str(),
                             false);
                     avb_ops_user_free(ops);
                     if (ret) {
-                        if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
-                            retval = VERITY_PARTITION;
+                        LOG(WARNING) << "Disable verity for " << mount_point;
+                        reboot_later = can_reboot;
+                        if (reboot_later) {
                             // w/o overlayfs available, also check for dedupe
-                            reboot_later = true;
-                            ++it;
-                            continue;
+                            if (!uses_overlayfs) {
+                                ++it;
+                                continue;
+                            }
+                            reboot(false);
                         }
-                        reboot(false);
                     } else if (fs_mgr_set_blk_ro(entry.blk_device, false)) {
                         fec::io fh(entry.blk_device.c_str(), O_RDWR);
-                        if (fh && fh.set_verity_status(false)) reboot_later = true;
+                        if (fh && fh.set_verity_status(false)) {
+                            LOG(WARNING) << "Disable verity for " << mount_point;
+                            reboot_later = can_reboot;
+                            if (reboot_later && !uses_overlayfs) {
+                                ++it;
+                                continue;
+                            }
+                        }
                     }
                 }
             }
             LOG(ERROR) << "Skipping " << mount_point;
-            retval = VERITY_PARTITION;
             it = partitions.erase(it);
             continue;
         }
@@ -318,7 +326,8 @@
     }
 
     // Mount overlayfs.
-    if (!fs_mgr_overlayfs_mount_all(&partitions)) {
+    errno = 0;
+    if (!fs_mgr_overlayfs_mount_all(&partitions) && errno) {
         retval = BAD_OVERLAY;
         PLOG(ERROR) << "Can not mount overlayfs for partitions";
     }
@@ -346,11 +355,15 @@
                 break;
             }
             if ((mount_point == "/") && (rentry.mount_point == "/system")) {
-                if (blk_device != "/dev/root") blk_device = rentry.blk_device;
+                blk_device = rentry.blk_device;
                 mount_point = "/system";
                 break;
             }
         }
+        if (blk_device == "/dev/root") {
+            auto from_fstab = GetEntryForMountPoint(&fstab, mount_point);
+            if (from_fstab) blk_device = from_fstab->blk_device;
+        }
         fs_mgr_set_blk_ro(blk_device, false);
 
         // Now remount!
diff --git a/fs_mgr/tests/adb-remount-test.sh b/fs_mgr/tests/adb-remount-test.sh
index a6baf1d..bd5a4fe 100755
--- a/fs_mgr/tests/adb-remount-test.sh
+++ b/fs_mgr/tests/adb-remount-test.sh
@@ -48,6 +48,7 @@
 TMPDIR=${TMPDIR:-/tmp}
 print_time=false
 start_time=`date +%s`
+ACTIVE_SLOT=
 
 ##
 ##  Helper Functions
@@ -77,6 +78,7 @@
       wc -l | grep '^1$' >/dev/null
     fi
 }
+
 [ "USAGE: inRecovery
 
 Returns: true if device is in recovery mode" ]
@@ -221,15 +223,23 @@
 
 Returns: waits until the device has returned for adb or optional timeout" ]
 adb_wait() {
+  local ret
   if [ -n "${1}" ]; then
     echo -n ". . . waiting `format_duration ${1}`" ${ANDROID_SERIAL} ${USB_ADDRESS} "${CR}"
     timeout --preserve-status --signal=KILL ${1} adb wait-for-device 2>/dev/null
-    local ret=${?}
+    ret=${?}
     echo -n "                                                                             ${CR}"
-    return ${ret}
   else
     adb wait-for-device
+    ret=${?}
   fi
+  if [ 0 = ${ret} -a -n "${ACTIVE_SLOT}" ]; then
+    local active_slot=`get_active_slot`
+    if [ X"${ACTIVE_SLOT}" != X"${active_slot}" ]; then
+      echo "${ORANGE}[  WARNING ]${NORMAL} Active slot changed from ${ACTIVE_SLOT} to ${active_slot}" >&2
+    fi
+  fi
+  return ${ret}
 }
 
 [ "USAGE: usb_status > stdout
@@ -254,33 +264,50 @@
 
 Returns: waits until the device has returned for fastboot or optional timeout" ]
 fastboot_wait() {
+  local ret
   # fastboot has no wait-for-device, but it does an automatic
   # wait and requires (even a nonsensical) command to do so.
   if [ -n "${1}" ]; then
     echo -n ". . . waiting `format_duration ${1}`" ${ANDROID_SERIAL} ${USB_ADDRESS} "${CR}"
     timeout --preserve-status --signal=KILL ${1} fastboot wait-for-device >/dev/null 2>/dev/null
-    local ret=${?}
+    ret=${?}
     echo -n "                                                                             ${CR}"
     ( exit ${ret} )
   else
     fastboot wait-for-device >/dev/null 2>/dev/null
   fi ||
     inFastboot
+  ret=${?}
+  if [ 0 = ${ret} -a -n "${ACTIVE_SLOT}" ]; then
+    local active_slot=`get_active_slot`
+    if [ X"${ACTIVE_SLOT}" != X"${active_slot}" ]; then
+      echo "${ORANGE}[  WARNING ]${NORMAL} Active slot changed from ${ACTIVE_SLOT} to ${active_slot}" >&2
+    fi
+  fi
+  return ${ret}
 }
 
 [ "USAGE: recovery_wait [timeout]
 
 Returns: waits until the device has returned for recovery or optional timeout" ]
 recovery_wait() {
+  local ret
   if [ -n "${1}" ]; then
     echo -n ". . . waiting `format_duration ${1}`" ${ANDROID_SERIAL} ${USB_ADDRESS} "${CR}"
     timeout --preserve-status --signal=KILL ${1} adb wait-for-recovery 2>/dev/null
-    local ret=${?}
+    ret=${?}
     echo -n "                                                                             ${CR}"
-    return ${ret}
   else
     adb wait-for-recovery
+    ret=${?}
   fi
+  if [ 0 = ${ret} -a -n "${ACTIVE_SLOT}" ]; then
+    local active_slot=`get_active_slot`
+    if [ X"${ACTIVE_SLOT}" != X"${active_slot}" ]; then
+      echo "${ORANGE}[  WARNING ]${NORMAL} Active slot changed from ${ACTIVE_SLOT} to ${active_slot}" >&2
+    fi
+  fi
+  return ${ret}
 }
 
 [ "any_wait [timeout]
@@ -326,7 +353,7 @@
     [ root != "`adb_sh echo '${USER}' </dev/null`" ]
 }
 
-[ "USAGE: fastboot_getvar var expected
+[ "USAGE: fastboot_getvar var expected >/dev/stderr
 
 Returns: true if var output matches expected" ]
 fastboot_getvar() {
@@ -350,6 +377,19 @@
   echo ${O} >&2
 }
 
+[ "USAGE: get_active_slot >/dev/stdout
+
+Returns: with a or b string reporting active slot" ]
+get_active_slot() {
+  if inAdb || inRecovery; then
+    get_property ro.boot.slot_suffix | tr -d _
+  elif inFastboot; then
+    fastboot_getvar current-slot 2>&1 | sed -n 's/current-slot: //p'
+  else
+    false
+  fi
+}
+
 [ "USAGE: restore
 
 Do nothing: should be redefined when necessary.  Called after cleanup.
@@ -583,6 +623,9 @@
 BUILD_DESCRIPTION=`get_property ro.build.description`
 [ -z "${BUILD_DESCRIPTION}" ] ||
   echo "${BLUE}[     INFO ]${NORMAL} ${BUILD_DESCRIPTION}" >&2
+ACTIVE_SLOT=`get_active_slot`
+[ -z "${ACTIVE_SLOT}" ] ||
+  echo "${BLUE}[     INFO ]${NORMAL} active slot is ${ACTIVE_SLOT}" >&2
 
 # Report existing partition sizes
 adb_sh ls -l /dev/block/by-name/ </dev/null 2>/dev/null |
@@ -1031,13 +1074,7 @@
   check_eq "${A}" "${B}" system after flash vendor
   adb_root ||
     die "adb root"
-  B="`adb_cat /vendor/hello`" &&
-    if ${is_userspace_fastboot} || ! ${overlayfs_needed}; then
-      die "re-read /vendor/hello after flash vendor"
-    else
-      echo "${ORANGE}[  WARNING ]${NORMAL} user fastboot missing required to invalidate, ignoring a failure" >&2
-      echo "${ORANGE}[  WARNING ]${NORMAL} re-read /vendor/hello after flash vendor" >&2
-    fi
+  B="`adb_cat /vendor/hello`"
   if ${is_userspace_fastboot} || ! ${overlayfs_needed}; then
     check_eq "cat: /vendor/hello: No such file or directory" "${B}" \
              vendor content after flash vendor
diff --git a/mkbootimg/unpack_bootimg.py b/mkbootimg/unpack_bootimg.py
index 6b5d5d0..36a5f9f 100755
--- a/mkbootimg/unpack_bootimg.py
+++ b/mkbootimg/unpack_bootimg.py
@@ -103,10 +103,11 @@
                                  ) # header + kernel
     image_info_list.append((ramdisk_offset, ramdisk_size, 'ramdisk'))
 
-    second_offset = page_size * (
-        num_header_pages + num_kernel_pages + num_ramdisk_pages
-    )  # header + kernel + ramdisk
-    image_info_list.append((second_offset, second_size, 'second'))
+    if second_size > 0:
+        second_offset = page_size * (
+                num_header_pages + num_kernel_pages + num_ramdisk_pages
+                )  # header + kernel + ramdisk
+        image_info_list.append((second_offset, second_size, 'second'))
 
     if recovery_dtbo_size > 0:
         image_info_list.append((recovery_dtbo_offset, recovery_dtbo_size,
diff --git a/sdcard/sdcard.cpp b/sdcard/sdcard.cpp
index e1de130..2b35819 100644
--- a/sdcard/sdcard.cpp
+++ b/sdcard/sdcard.cpp
@@ -27,6 +27,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <vector>
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
@@ -99,14 +100,21 @@
 
 static bool sdcardfs_setup(const std::string& source_path, const std::string& dest_path,
                            uid_t fsuid, gid_t fsgid, bool multi_user, userid_t userid, gid_t gid,
-                           mode_t mask, bool derive_gid, bool default_normal, bool use_esdfs) {
+                           mode_t mask, bool derive_gid, bool default_normal, bool unshared_obb,
+                           bool use_esdfs) {
+    // Add new options at the end of the vector.
+    std::vector<std::string> new_opts_list;
+    if (multi_user) new_opts_list.push_back("multiuser,");
+    if (derive_gid) new_opts_list.push_back("derive_gid,");
+    if (default_normal) new_opts_list.push_back("default_normal,");
+    if (unshared_obb) new_opts_list.push_back("unshared_obb,");
     // Try several attempts, each time with one less option, to gracefully
     // handle older kernels that aren't updated yet.
-    for (int i = 0; i < 4; i++) {
+    for (int i = 0; i <= new_opts_list.size(); ++i) {
         std::string new_opts;
-        if (multi_user && i < 3) new_opts += "multiuser,";
-        if (derive_gid && i < 2) new_opts += "derive_gid,";
-        if (default_normal && i < 1) new_opts += "default_normal,";
+        for (int j = 0; j < new_opts_list.size() - i; ++j) {
+            new_opts += new_opts_list[j];
+        }
 
         auto opts = android::base::StringPrintf("fsuid=%d,fsgid=%d,%smask=%d,userid=%d,gid=%d",
                                                 fsuid, fsgid, new_opts.c_str(), mask, userid, gid);
@@ -142,13 +150,14 @@
     return true;
 }
 
-static bool sdcardfs_setup_secondary(const std::string& default_path, const std::string& source_path,
-                                     const std::string& dest_path, uid_t fsuid, gid_t fsgid,
-                                     bool multi_user, userid_t userid, gid_t gid, mode_t mask,
-                                     bool derive_gid, bool default_normal, bool use_esdfs) {
+static bool sdcardfs_setup_secondary(const std::string& default_path,
+                                     const std::string& source_path, const std::string& dest_path,
+                                     uid_t fsuid, gid_t fsgid, bool multi_user, userid_t userid,
+                                     gid_t gid, mode_t mask, bool derive_gid, bool default_normal,
+                                     bool unshared_obb, bool use_esdfs) {
     if (use_esdfs) {
         return sdcardfs_setup(source_path, dest_path, fsuid, fsgid, multi_user, userid, gid, mask,
-                              derive_gid, default_normal, use_esdfs);
+                              derive_gid, default_normal, unshared_obb, use_esdfs);
     } else {
         return sdcardfs_setup_bind_remount(default_path, dest_path, gid, mask);
     }
@@ -156,7 +165,7 @@
 
 static void run_sdcardfs(const std::string& source_path, const std::string& label, uid_t uid,
                          gid_t gid, userid_t userid, bool multi_user, bool full_write,
-                         bool derive_gid, bool default_normal, bool use_esdfs) {
+                         bool derive_gid, bool default_normal, bool unshared_obb, bool use_esdfs) {
     std::string dest_path_default = "/mnt/runtime/default/" + label;
     std::string dest_path_read = "/mnt/runtime/read/" + label;
     std::string dest_path_write = "/mnt/runtime/write/" + label;
@@ -167,16 +176,17 @@
         // Multi-user storage is fully isolated per user, so "other"
         // permissions are completely masked off.
         if (!sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,
-                            AID_SDCARD_RW, 0006, derive_gid, default_normal, use_esdfs) ||
+                            AID_SDCARD_RW, 0006, derive_gid, default_normal, unshared_obb,
+                            use_esdfs) ||
             !sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_read, uid, gid,
                                       multi_user, userid, AID_EVERYBODY, 0027, derive_gid,
-                                      default_normal, use_esdfs) ||
+                                      default_normal, unshared_obb, use_esdfs) ||
             !sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_write, uid, gid,
                                       multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0027,
-                                      derive_gid, default_normal, use_esdfs) ||
+                                      derive_gid, default_normal, unshared_obb, use_esdfs) ||
             !sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_full, uid, gid,
                                       multi_user, userid, AID_EVERYBODY, 0007, derive_gid,
-                                      default_normal, use_esdfs)) {
+                                      default_normal, unshared_obb, use_esdfs)) {
             LOG(FATAL) << "failed to sdcardfs_setup";
         }
     } else {
@@ -184,16 +194,17 @@
         // the Android directories are masked off to a single user
         // deep inside attr_from_stat().
         if (!sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,
-                            AID_SDCARD_RW, 0006, derive_gid, default_normal, use_esdfs) ||
+                            AID_SDCARD_RW, 0006, derive_gid, default_normal, unshared_obb,
+                            use_esdfs) ||
             !sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_read, uid, gid,
                                       multi_user, userid, AID_EVERYBODY, full_write ? 0027 : 0022,
-                                      derive_gid, default_normal, use_esdfs) ||
+                                      derive_gid, default_normal, unshared_obb, use_esdfs) ||
             !sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_write, uid, gid,
                                       multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0022,
-                                      derive_gid, default_normal, use_esdfs) ||
+                                      derive_gid, default_normal, unshared_obb, use_esdfs) ||
             !sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_full, uid, gid,
                                       multi_user, userid, AID_EVERYBODY, 0007, derive_gid,
-                                      default_normal, use_esdfs)) {
+                                      default_normal, unshared_obb, use_esdfs)) {
             LOG(FATAL) << "failed to sdcardfs_setup";
         }
     }
@@ -216,7 +227,8 @@
                << "    -U: specify user ID that owns device"
                << "    -m: source_path is multi-user"
                << "    -w: runtime write mount has full write access"
-               << "    -P  preserve owners on the lower file system";
+               << "    -P: preserve owners on the lower file system"
+               << "    -o: obb dir doesn't need to be shared between users";
     return 1;
 }
 
@@ -230,6 +242,7 @@
     bool full_write = false;
     bool derive_gid = false;
     bool default_normal = false;
+    bool unshared_obb = false;
     int i;
     struct rlimit rlim;
     int fs_version;
@@ -238,7 +251,7 @@
     android::base::InitLogging(argv, android::base::LogdLogger(android::base::SYSTEM));
 
     int opt;
-    while ((opt = getopt(argc, argv, "u:g:U:mwGi")) != -1) {
+    while ((opt = getopt(argc, argv, "u:g:U:mwGio")) != -1) {
         switch (opt) {
             case 'u':
                 uid = strtoul(optarg, NULL, 10);
@@ -261,8 +274,12 @@
             case 'i':
                 default_normal = true;
                 break;
+            case 'o':
+                unshared_obb = true;
+                break;
             case '?':
             default:
+                LOG(ERROR) << "Unknown option: '" << opt << "'";
                 return usage();
         }
     }
@@ -304,6 +321,6 @@
     }
 
     run_sdcardfs(source_path, label, uid, gid, userid, multi_user, full_write, derive_gid,
-                 default_normal, !should_use_sdcardfs());
+                 default_normal, unshared_obb, !should_use_sdcardfs());
     return 1;
 }