Changing OOM range to 0, 1000 and tweaking OOM algorithm.

content/browser/zygote_host_linux.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/zygote_host_linux.h"
 
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ skipping 254 matching lines @@
     if (!UnixDomainSocket::SendMsg(control_fd_, pickle.data(), pickle.size(),
                                    fds))
       return base::kNullProcessHandle;
 
     if (ReadReply(&pid, sizeof(pid)) != sizeof(pid))
       return base::kNullProcessHandle;
     if (pid <= 0)
       return base::kNullProcessHandle;
   }
 
-  const int kRendererScore = 5;
-  AdjustRendererOOMScore(pid, kRendererScore);
+  // This is just a starting score for a renderer or extension (the
+  // only types of processes that will be started this way).  It will
+  // get adjusted as time goes on.  (This is the same value as
+  // chrome::kLowestRendererOomScore in chrome/chrome_constants.h, but
+  // that's not something we can include here.)
+  const int kLowestRendererOomScore = 300;
+  AdjustRendererOOMScore(pid, kLowestRendererOomScore);
 
   return pid;
 }
 
 void ZygoteHost::AdjustRendererOOMScore(base::ProcessHandle pid, int score) {
-  // 1) You can't change the oom_adj of a non-dumpable process (EPERM) unless
-  //    you're root. Because of this, we can't set the oom_adj from the browser
-  //    process.
+  // 1) You can't change the oom_score_adj of a non-dumpable process
+  //    (EPERM) unless you're root. Because of this, we can't set the
+  //    oom_adj from the browser process.
   //
-  // 2) We can't set the oom_adj before entering the sandbox because the
-  //    zygote is in the sandbox and the zygote is as critical as the browser
-  //    process. Its oom_adj value shouldn't be changed.
+  // 2) We can't set the oom_score_adj before entering the sandbox
+  //    because the zygote is in the sandbox and the zygote is as
+  //    critical as the browser process. Its oom_adj value shouldn't
+  //    be changed.
   //
-  // 3) A non-dumpable process can't even change its own oom_adj because it's
-  //    root owned 0644. The sandboxed processes don't even have /proc, but one
-  //    could imagine passing in a descriptor from outside.
+  // 3) A non-dumpable process can't even change its own oom_score_adj
+  //    because it's root owned 0644. The sandboxed processes don't
+  //    even have /proc, but one could imagine passing in a descriptor
+  //    from outside.
   //
   // So, in the normal case, we use the SUID binary to change it for us.
   // However, Fedora (and other SELinux systems) don't like us touching other
-  // process's oom_adj values
+  // process's oom_score_adj (or oom_adj) values
   // (https://bugzilla.redhat.com/show_bug.cgi?id=581256).
   //
   // The offical way to get the SELinux mode is selinux_getenforcemode, but I
   // don't want to add another library to the build as it's sure to cause
   // problems with other, non-SELinux distros.
   //
   // So we just check for /selinux. This isn't foolproof, but it's not bad
   // and it's easy.
 
   static bool selinux;
@@ skipping 78 matching lines @@
       !read_pickle.ReadInt(&iter, &tmp_exit_code)) {
     LOG(WARNING) << "Error parsing GetTerminationStatus response from zygote.";
     return base::TERMINATION_STATUS_NORMAL_TERMINATION;
   }
 
   if (exit_code)
     *exit_code = tmp_exit_code;
 
   return static_cast<base::TerminationStatus>(status);
 }