Allow exempting some processes from overcommit

libmemory-patches/libmemory-patches.h

@@ -40,6 +40,7 @@ struct current_memory_info
 
 LIBMEMORY_PATCHES_API extern struct current_memory_info get_current_memory_info(void);
 LIBMEMORY_PATCHES_API int overcommit_prevention_enabled(void);
+LIBMEMORY_PATCHES_API int overcommit_prevention_exempt(void);
 LIBMEMORY_PATCHES_API BOOL memory_available_for_commit(size_t size);
 LIBMEMORY_PATCHES_API void touch_committed_pages(void* base, size_t size, uint32_t protect);
 LIBMEMORY_PATCHES_API BOOL has_write_flags(uint32_t protect);

libmemory-patches/overcommit.c

@@ -39,6 +39,90 @@ static const uint32_t page_writecopy_flags =
     PAGE_WRITECOPY;
 
 
+/***********************************************************************
+ *           overcommit_prevention_exempt
+ *
+ * Determines if this process is exempt from overcommit prevention, but
+ * should still have it's writable memory mapped pages touched to ensure
+ * accurate memory tracking.
+ */
+int overcommit_prevention_exempt(void)
+{
+    static int overcommit_exempt = -1;
+
+    if (overcommit_exempt == -1)
+    {
+        int exempt_debug;
+        {
+            const char *debug_env_var = getenv( "WINE_PREVENT_OVERCOMMIT_EXEMPT_DEBUG" );
+            exempt_debug = debug_env_var && atoi(debug_env_var);
+        }
+
+        const char *env_var = getenv( "WINE_PREVENT_OVERCOMMIT_EXEMPT" );
+        if (env_var)
+        {
+            FILE *fp;
+            if (fp = fopen("/proc/self/cmdline", "r"))
+            {
+                char argument[1024];
+                char buffer[1024];
+                size_t arg_offset = 0;
+                if (exempt_debug)
+                {
+                    puts("/proc/self/cmdline tolower:");
+                }
+                size_t read;
+                do
+                {
+                    read = fread(buffer, 1, sizeof buffer, fp);
+                    for (size_t i = 0; i < read; i++)
+                    {
+                        if (arg_offset < (sizeof argument) - 1)
+                        {
+                            argument[arg_offset++] = tolower(buffer[i]);
+                        }
+                        else
+                        {
+                            argument[(sizeof argument) - 1] = '\0';
+                        }
+
+                        if (buffer[i] == '\0')
+                        {
+                            int non_empty_argument = arg_offset > 1;
+                            arg_offset = 0;
+
+                            if (non_empty_argument && exempt_debug)
+                            {
+                                puts(argument);
+                            }
+
+                            if (non_empty_argument && strstr(argument, env_var))
+                            {
+                                if (exempt_debug)
+                                {
+                                    printf(
+                                        "detected process name from WINE_PREVENT_OVERCOMMIT_EXEMPT '%s' is present in cmdline tolower argument '%s'. overcommit prevention will be turned off for this specific process.\n", 
+                                        env_var, 
+                                        argument);
+                                }
+                                overcommit_exempt = 1;
+                            }
+                        }
+                    }
+                } while (read > 0);
+                fclose(fp);
+            }
+        }
+
+        if (overcommit_exempt == -1)
+        {
+            overcommit_exempt = 0;
+        }
+    }
+
+    return overcommit_exempt;
+}
+
 /***********************************************************************
  *           overcommit_prevention_enabled
  *
@@ -48,6 +132,14 @@ int overcommit_prevention_enabled(void)
 {
     static int prevent_overcommit = -1;
 
+    if (prevent_overcommit == -1)
+    {
+        if (overcommit_prevention_exempt())
+        {
+            prevent_overcommit = 0;
+        }
+    }
+
     if (prevent_overcommit == -1)
     {
         const char *env_var = getenv( "WINE_PREVENT_OVERCOMMIT" );

patches/wine-overcommit-prevention-support.patch

@@ -241,7 +241,7 @@ index abe1b4dc4ec424c0864d18e726537e680d2ab883..e55d7e68d1b8d3967316f1101cb0ce9b
          VIRTUAL_DEBUG_DUMP_VIEW( view );
 +
 +        /* if overcommit prevention is enabled and we performed a commit, then touch the commited pages */
-+        if (write_consumes_memory && overcommit_prevention_enabled()) {
++        if (write_consumes_memory && (overcommit_prevention_enabled() || overcommit_prevention_exempt())) {
 +            touch_committed_pages(view->base, size, protect);
 +        }
      }
@@ -267,7 +267,7 @@ index abe1b4dc4ec424c0864d18e726537e680d2ab883..e55d7e68d1b8d3967316f1101cb0ce9b
          *size_ptr = size;
 +
 +        /* if overcommit prevention is enabled and we performed a commit, then touch the commited pages */
-+        if ((type & MEM_COMMIT) && overcommit_prevention_enabled()) {
++        if ((type & MEM_COMMIT) && (overcommit_prevention_enabled() || overcommit_prevention_exempt())) {
 +            touch_committed_pages(base, size, protect);
 +        }
      }
@@ -295,7 +295,7 @@ index abe1b4dc4ec424c0864d18e726537e680d2ab883..e55d7e68d1b8d3967316f1101cb0ce9b
              status = set_protection( view, base, size, new_prot );
 +
 +            /* if overcommit prevention is enabled and write access was granted then touch the pages */
-+            if (overcommit_prevention_enabled() && write_or_copy_added) {
++            if ((overcommit_prevention_enabled() || overcommit_prevention_exempt()) && write_or_copy_added) {
 +                touch_committed_pages(base, size, new_prot);
 +            }
          }