Martin Schwidefsky wrote: > diff -urpN linux-2.6/mm/memory.c linux-2.6-patched/mm/memory.c > --- linux-2.6/mm/memory.c 2006-09-01 12:50:24.000000000 +0200 > +++ linux-2.6-patched/mm/memory.c 2006-09-01 12:50:24.000000000 +0200 > @@ -2523,6 +2523,31 @@ int make_pages_present(unsigned long add > BUG_ON(addr >= end); > BUG_ON(end > vma->vm_end); > len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; > + > + if (page_host_discards() && (vma->vm_flags & VM_LOCKED)) { > + int rlen = len; > + ret = 0; > + while (rlen > 0) { > + struct page *page_refs[32]; > + int chunk, cret, i; > + > + chunk = rlen < 32 ? rlen : 32; > + cret = get_user_pages(current, current->mm, addr, > + chunk, write, 0, > + page_refs, NULL); > + if (cret > 0) { > + for (i = 0; i < cret; i++) > + page_cache_release(page_refs[i]); > + ret += cret; > + } > + if (cret < chunk) > + return ret ? : cret; > + addr += 32*PAGE_SIZE; > + rlen -= 32; > + } > + return ret == len ? 0 : -1; > + } > + > ret = get_user_pages(current, current->mm, addr, > len, write, 0, NULL, NULL); > if (ret < 0) > This seems like a bit of unneeded complexity. Since you've already changed get_user_pages, why not add a follow flag to release the page cache, and simply pass it to get_user_pages, instead of trying to fetch the page list back. In particular, write and force arguments to get_user_pages look very ripe for combining into a flags field. Sure, get_user_pages now has a bit more work to do, but it is already a monster, and I think it would keep make_page_present much cleaner. Zach Zach