> How is the compiler meant to optimise away "cond" if it's a function > call? Inlines can be optimized away. These tests are usually inlines. > What did I miss? If nothing, then I will revert this particular change > and Rafael will need to be sure his patch is not using VM_BUG_ON to call > a function with side-effects. Do you have an example where the code is actually different, or are you just speculating? FWIW for my config both generates the same code: size vmlinux-andi-vmbug vmlinux-vmbug-nothing text data bss dec hex filename 11809704 1457352 1159168 14426224 dc2070 vmlinux-andi-vmbug 11809704 1457352 1159168 14426224 dc2070 vmlinux-vmbug-nothing -Andi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>