diff --git a/plugins/coverbrowser.koplugin/bookinfomanager.lua b/plugins/coverbrowser.koplugin/bookinfomanager.lua
index 26f2d479f..f4f9f3a6e 100644
--- a/plugins/coverbrowser.koplugin/bookinfomanager.lua
+++ b/plugins/coverbrowser.koplugin/bookinfomanager.lua
@@ -308,7 +308,8 @@ function BookInfoManager:extractBookInfo(filepath, cover_specs)
         -- cre.initCache("", 1024*1024*32) -- empty path = no cache
         -- But it's best to use a cache for quicker and less memory
         -- usage when opening big books:
-        cre.initCache(self.tmpcr3cache, 0) -- 0 = previous book caches are removed when opening a book
+        cre.initCache(self.tmpcr3cache, 0, -- 0 = previous book caches are removed when opening a book
+            true, G_reader_settings:readSetting("cre_storage_size_factor")) -- avoid CRE WARNINGs
         self.cre_cache_overriden = true
     end
 
@@ -440,6 +441,8 @@ function BookInfoManager:extractBookInfo(filepath, cover_specs)
             end
         end
         DocumentRegistry:closeDocument(filepath)
+    else
+        loaded = false
     end
     if not loaded then
         dbrow.unsupported = _("not readable by engine")
@@ -513,7 +516,7 @@ function BookInfoManager:collectSubprocesses()
         local i = 1
         while i <= #self.subprocesses_pids do -- clean in-place
             local pid = self.subprocesses_pids[i]
-            if xutil.isSubProcessDone(pid) then
+            if util.isSubProcessDone(pid) then
                 table.remove(self.subprocesses_pids, i)
             else
                 i = i + 1
@@ -551,7 +554,7 @@ end
 function BookInfoManager:terminateBackgroundJobs()
     logger.dbg("terminating", #self.subprocesses_pids, "subprocesses")
     for i=1, #self.subprocesses_pids do
-        xutil.terminateSubProcess(self.subprocesses_pids[i])
+        util.terminateSubProcess(self.subprocesses_pids[i])
     end
 end
 
@@ -587,7 +590,7 @@ function BookInfoManager:extractInBackground(files)
     self.cleanup_needed = true -- so we will remove temporary cache directory created by subprocess
 
     -- Run task in sub-process, and remember its pid
-    local task_pid = xutil.runInSubProcess(task)
+    local task_pid = util.runInSubProcess(task)
     if not task_pid then
         logger.warn("Failed lauching background extraction sub-process (fork failed)")
         return false -- let caller know it failed
diff --git a/plugins/coverbrowser.koplugin/xutil.lua b/plugins/coverbrowser.koplugin/xutil.lua
index 270de476e..263734a97 100644
--- a/plugins/coverbrowser.koplugin/xutil.lua
+++ b/plugins/coverbrowser.koplugin/xutil.lua
@@ -1,56 +1,9 @@
 local ffi = require("ffi")
-local C = ffi.C
 
 -- Utilities functions needed by this plugin, but that may be added to
 -- existing base/ffi/ files
 local xutil = {}
 
-
--- Sub-process management (may be put into base/ffi/util.lua)
-function xutil.runInSubProcess(func)
-    local pid = C.fork()
-    if pid == 0 then -- child process
-        -- Just run the provided lua code object in this new process,
-        -- and exit immediatly (so we do not release drivers and
-        -- resources still used by parent process)
-        func()
-        os.exit(0)
-    end
-    -- parent/main process, return pid of child
-    if pid == -1 then -- On failure, -1 is returned in the parent
-        return false
-    end
-    return pid
-end
-
-function xutil.isSubProcessDone(pid)
-    local status = ffi.new('int[1]')
-    local ret = C.waitpid(pid, status, 1) -- 1 = WNOHANG : don't wait, just tell
-    -- status = tonumber(status[0])
-    -- local logger = require("logger")
-    -- logger.dbg("waitpid for", pid, ":", ret, "/", status)
-    -- still running: ret = 0 , status = 0
-    -- exited: ret = pid , status = 0 or 9 if killed
-    -- no more running: ret = -1 , status = 0
-    if ret == pid or ret == -1 then
-        return true
-    end
-end
-
-function xutil.terminateSubProcess(pid)
-    local done = xutil.isSubProcessDone(pid)
-    if not done then
-        -- local logger = require("logger")
-        -- logger.dbg("killing subprocess", pid)
-        -- we kill with signal 9/SIGKILL, which may be violent, but ensures
-        -- that it is terminated (a process may catch or ignore SIGTERM)
-        C.kill(pid, 9)
-        -- process will still have to be collected with calls to util.isSubProcessDone(),
-        -- which may still return false for some small amount of time after our kill()
-    end
-end
-
-
 -- Data compression/decompression of strings thru zlib (may be put in a new base/ffi/zlib.lua)
 -- from http://luajit.org/ext_ffi_tutorial.html
 ffi.cdef[[
@@ -79,7 +32,6 @@ function xutil.zlib_uncompress(zdata, datalen)
     return ffi.string(buf, buflen[0])
 end
 
-
 -- Not provided by base/thirdparty/lua-ljsqlite3/init.lua
 -- Add a timeout to a lua-ljsqlite3 connection
 -- We need that if we have multiple processes accessing the same