Re: [patch 5/9] Guest page hinting: mlocked pages.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux