diff --git a/libc/kernel/common/linux/backing-dev.h b/libc/kernel/common/linux/backing-dev.h
index 4996d2c..553cca7 100644
--- a/libc/kernel/common/linux/backing-dev.h
+++ b/libc/kernel/common/linux/backing-dev.h
@@ -7,47 +7,55 @@
  ***   structures, and macros generated from the original header, and thus,
  ***   contains no copyrightable information.
  ***
+ ***   To edit the content of this header, modify the corresponding
+ ***   source file (e.g. under external/kernel-headers/original/) then
+ ***   run bionic/libc/kernel/tools/update_all.py
+ ***
+ ***   Any manual change here will be lost the next time this script will
+ ***   be run. You've been warned!
+ ***
  ****************************************************************************
  ****************************************************************************/
 #ifndef _LINUX_BACKING_DEV_H
 #define _LINUX_BACKING_DEV_H
-
 #include <asm/atomic.h>
-
 enum bdi_state {
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
  BDI_pdflush,
  BDI_write_congested,
  BDI_read_congested,
  BDI_unused,
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 };
-
 typedef int (congested_fn)(void *, int);
-
 struct backing_dev_info {
  unsigned long ra_pages;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
  unsigned long state;
  unsigned int capabilities;
  congested_fn *congested_fn;
  void *congested_data;
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
  void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
  void *unplug_io_data;
 };
-
 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001  
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define BDI_CAP_NO_WRITEBACK 0x00000002  
 #define BDI_CAP_MAP_COPY 0x00000004  
 #define BDI_CAP_MAP_DIRECT 0x00000008  
 #define BDI_CAP_READ_MAP 0x00000010  
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define BDI_CAP_WRITE_MAP 0x00000020  
 #define BDI_CAP_EXEC_MAP 0x00000040  
 #define BDI_CAP_VMFLAGS   (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
-
 #if defined(VM_MAYREAD) && BDI_CAP_READ_MAP != (VM_MAYREAD || BDI_CAP_WRITE_MAP != (VM_MAYWRITE || BDI_CAP_EXEC_MAP != VM_MAYEXEC))
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #error please change backing_dev_info::capabilities flags
 #endif
-
 #define bdi_cap_writeback_dirty(bdi)   (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
 #define bdi_cap_account_dirty(bdi)   (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define mapping_cap_writeback_dirty(mapping)   bdi_cap_writeback_dirty((mapping)->backing_dev_info)
 #define mapping_cap_account_dirty(mapping)   bdi_cap_account_dirty((mapping)->backing_dev_info)
 #endif