tor-browser

commit b77e723fc778eb0b394164a076c5b59befbc04cf
parent 0d1a10fda0ac9aa36277e6955fcb2874b4c7133b
Author: Andrew Osmond <aosmond@mozilla.com>
Date:   Fri,  3 Oct 2025 14:54:03 +0000

Bug 1987906. r=lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D266841

Diffstat:
M
gfx/ipc/GPUProcessManager.cpp
 | 
12
++++++++++++
M
gfx/ipc/GPUProcessManager.h
 | 
6
++++++
M
modules/libpref/init/StaticPrefList.yaml
 | 
9
++++++++-

3 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/gfx/ipc/GPUProcessManager.cpp b/gfx/ipc/GPUProcessManager.cpp
@@ -209,6 +209,15 @@ void GPUProcessManager::NotifyBatteryInfo(
   }
 }
 
+void GPUProcessManager::MaybeCrashIfGpuProcessOnceStable() {
+  if (StaticPrefs::layers_gpu_process_allow_fallback_to_parent_AtStartup()) {
+    return;
+  }
+  MOZ_RELEASE_ASSERT(!gfxConfig::IsEnabled(Feature::GPU_PROCESS));
+  MOZ_RELEASE_ASSERT(!mProcessStableOnce,
+                     "Fallback to parent process not allowed!");
+}
+
 void GPUProcessManager::ResetProcessStable() {
   mTotalProcessAttempts++;
   mProcessStable = false;
@@ -333,6 +342,8 @@ bool GPUProcessManager::MaybeDisableGPUProcess(const char* aMessage,
     gfxCriticalNote << aMessage;
 
     gfxPlatform::DisableGPUProcess();
+
+    MaybeCrashIfGpuProcessOnceStable();
   }
 
   mozilla::glean::gpu_process::feature_status.Set(
@@ -936,6 +947,7 @@ void GPUProcessManager::OnProcessUnexpectedShutdown(GPUProcessHost* aHost) {
   // long enough, reset the counter so that we don't disable the process too
   // eagerly.
   if (IsProcessStable(TimeStamp::Now())) {
+    mProcessStableOnce = true;
     mUnstableProcessAttempts = 0;
   } else {
     mUnstableProcessAttempts++;
diff --git a/gfx/ipc/GPUProcessManager.h b/gfx/ipc/GPUProcessManager.h
@@ -284,6 +284,11 @@ class GPUProcessManager final : public GPUProcessHost::Listener {
   bool FallbackFromAcceleration(wr::WebRenderError aError,
                                 const nsCString& aMsg);
 
+  // Crashes the parent process if we are disabling the GPU process and we
+  // ever once had a stable GPU process. This is to avoid fallback into the
+  // parent when we know the configuration allows for the GPU process.
+  void MaybeCrashIfGpuProcessOnceStable();
+
   void ResetProcessStable();
 
   // Returns true if the composting pocess is currently considered to be stable.
@@ -385,6 +390,7 @@ class GPUProcessManager final : public GPUProcessHost::Listener {
   GPUProcessHost* mProcess;
   uint64_t mProcessToken;
   bool mProcessStable;
+  bool mProcessStableOnce = false;
   Maybe<wr::WebRenderError> mLastError;
   Maybe<nsCString> mLastErrorMsg;
   GPUChild* mGPUChild;
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
@@ -9523,6 +9523,13 @@
 #endif
   mirror: always
 
+# If true, allow the parent process as a fallback for compositing due to an
+# unstable GPU process, otherwise simply crash the parent process.
+- name: layers.gpu-process.allow-fallback-to-parent
+  type: bool
+  value: false
+  mirror: once
+
 - name: layers.gpu-process.allow-software
   type: bool
 #if defined(XP_WIN)
@@ -9602,7 +9609,7 @@
 # restarts.
 - name: layers.gpu-process.stable.min-uptime-ms
   type: RelaxedAtomicInt32
-  value: 4 * 60000
+  value: 30000
   mirror: always
 
 # Note: This pref will only be used if it is less than layers.gpu-process.max_restarts.