From: Linuxppc-dev Till Smejkal > Sent: 13 March 2017 22:14 > The only way until now to create a new memory map was via the exported > function 'mm_alloc'. Unfortunately, this function not only allocates a new > memory map, but also completely initializes it. However, with the > introduction of first class virtual address spaces, some initialization > steps done in 'mm_alloc' are not applicable to the memory maps needed for > this feature and hence would lead to errors in the kernel code. > > Instead of introducing a new function that can allocate and initialize > memory maps for first class virtual address spaces and potentially > duplicate some code, I decided to split the mm_alloc function as well as > the 'mm_init' function that it uses. > > Now there are four functions exported instead of only one. The new > 'mm_alloc' function only allocates a new mm_struct and zeros it out. If one > want to have the old behavior of mm_alloc one can use the newly introduced > function 'mm_alloc_and_setup' which not only allocates a new mm_struct but > also fully initializes it. ... That looks like bugs waiting to happen. You need unchanged code to fail to compile. David
