Jiri Kosina wrote on Thu, Mar 07, 2019: > > I'm not sure this is correct in all cases. If > > > > addr = 4095 > > vma->vm_end = 4096 > > pages = 1000 > > > > then `end' is 4096 and `(end - addr) << PAGE_SHIFT' is zero, but it > > should have been 1. > > Good catch! It should rather be something like > > unsigned long pages = (end >> PAGE_SHIFT) - (addr >> PAGE_SHIFT);
That would be 0 for addr = 0 and vma->vm_end = 1; I assume we would still want to count that as one page. I'm not too familiar with this area of the code, but I think there's a handy macro we can use for this, perhaps DIV_ROUND_UP(end - addr, PAGE_SIZE) ? kernel/kexec_core.c has defined PAGE_COUNT() which seems more appropriate but I do not see a global equivalent #define PAGE_COUNT(x) (((x) + PAGE_SIZE - 1) >> PAGE_SHIFT) -- Dominique
