Re: writable swap cache explained (it's weird)

Stephen C. Tweedie (sct@redhat.com)
Fri, 31 Jul 1998 10:57:13 +0100


Hi,

On Thu, 30 Jul 1998 23:35:29 +0100 (BST), alan@lxorguk.ukuu.org.uk
(Alan Cox) said:

> 2.0.x question - why did this work ok in 2.0 (did it in fact work ok in 2.0)

Early 2.0 would refuse to swap out the shared pages. 2.0.34+ will
silently break the alias during swapping. The change is due to the

diff -u --recursive --new-file v2.0.33/linux/mm/vmscan.c linux/mm/vmscan.c
--- v2.0.33/linux/mm/vmscan.c Tue Mar 10 13:19:09 1998
+++ linux/mm/vmscan.c Wed Jun 3 15:17:50 1998
@@ -120,8 +120,6 @@
if (vma->vm_ops->swapout(vma, address - vma->vm_start + vma->vm_offset, page_table))
kill_proc(pid, SIGBUS, 1);
} else {
- if (page_map->count != 1)
- return 0;
if (!(entry = get_swap_page()))
return 0;
vma->vm_mm->rss--;

patch in 2.0.34.

--Stephen

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