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It seems to have an exciting return code as > > well. > > > > I suppose size is the alignment target? Maybe rename the parameter too? > > Yes, when the kdoc is there it'll be more obvious. So far "size" is ok to > me, but if you have better suggestion please shoot - whatever I came up > with so far seems to be too long, and maybe not necessary when kdoc will be > available too. I would call it align not size > > For the purposes of VFIO do we need to be careful about math overflow here: > > > > loff_t off_end = off + len; > > loff_t off_align = round_up(off, size); > > > > ? > > IIUC the 1st one was covered by the latter check here: > > (off + len_pad) < off > > Indeed I didn't see what makes sure the 2nd won't overflow. I'm not sure the < tests are safe in this modern world. I would use the overflow helpers directly and remove the < overflow checks. > +/** > + * mm_get_unmapped_area_aligned - Allocate an aligned virtual address > + * @filp: file target of the mmap() request > + * @addr: hint address from mmap() request > + * @len: len of the mmap() request > + * @off: file offset of the mmap() request > + * @flags: flags of the mmap() request > + * @size: the size of alignment the caller requests Just "the alignment the caller requests" > + * @vm_flags: the vm_flags passed from get_unmapped_area() caller > + * > + * This function should normally be used by a driver's specific > + * get_unmapped_area() handler to provide a properly aligned virtual > + * address for a specific mmap() request. The caller should pass in most > + * of the parameters from the get_unmapped_area() request, but properly > + * specify @size as the alignment needed. .. "The function willl try to return a VMA starting address such that ret % size == 0" Jason