Hi,
while reading through uvm code I stubled accross a piece of code that
appears to be buggy. Here's the proposed patch, rational follows:
Index: uvm_vnode.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_vnode.c,v
retrieving revision 1.71
diff -u -r1.71 uvm_vnode.c
--- uvm_vnode.c 18 May 2010 04:41:14 -0000 1.71
+++ uvm_vnode.c 7 Jun 2011 16:42:15 -0000
@@ -924,8 +924,8 @@
*/
if (flags & PGO_DEACTIVATE) {
- if ((pp->pg_flags & PQ_INACTIVE) == 0 &&
- pp->wire_count == 0) {
+ if ((ptmp->pg_flags & PQ_INACTIVE) == 0 &&
+ ptmp->wire_count == 0) {
pmap_page_protect(ptmp, VM_PROT_NONE);
uvm_pagedeactivate(ptmp);
}
This code handles (among other things) write back of dirty pages to disk.
It calls uvm_pager_put to do the actual IO (one call per page). To improve
performance, uvm_pager_put is allowed to do IO for adjacent pages as well
and returns an array of all pages that must be unbusied by the caller
(uvn_flush).
The code above is part of the loop that does this. pp is the initial page
passed to uvm_pager_put and ptmp is the page that we are about to unbusy.
Thus we should IMHO check the PQ_INACTIVE flag and the wire_count of ptmp
instead of pp.
Coments appreciated!
regards Christian
