Author: markj
Date: Tue Aug 27 14:06:34 2019
New Revision: 351547
URL: https://svnweb.freebsd.org/changeset/base/351547
Log:
Fix several logic issues in domainset_empty_vm().
- Don't add 1 to the result of DOMAINSET_FLS.
- Do not modify domainsets containing only empty domains.
- Always flatten a _PREFER policy to _ROUNDROBIN if the preferred
domain is empty. Previously we were doing this only when ds_cnt > 1.
These bugs could cause hangs during boot if a VM domain is empty.
Tested by: hselasky
Reviewed by: hselasky, kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21420
Modified:
head/sys/kern/kern_cpuset.c
Modified: head/sys/kern/kern_cpuset.c
==============================================================================
--- head/sys/kern/kern_cpuset.c Tue Aug 27 14:04:32 2019 (r351546)
+++ head/sys/kern/kern_cpuset.c Tue Aug 27 14:06:34 2019 (r351547)
@@ -500,25 +500,31 @@ _domainset_create(struct domainset *domain, struct dom
static bool
domainset_empty_vm(struct domainset *domain)
{
- int i, j, max;
+ domainset_t empty;
+ int i, j;
- max = DOMAINSET_FLS(&domain->ds_mask) + 1;
- for (i = 0; i < max; i++)
- if (DOMAINSET_ISSET(i, &domain->ds_mask) && VM_DOMAIN_EMPTY(i))
- DOMAINSET_CLR(i, &domain->ds_mask);
+ DOMAINSET_ZERO(&empty);
+ for (i = 0; i < vm_ndomains; i++)
+ if (VM_DOMAIN_EMPTY(i))
+ DOMAINSET_SET(i, &empty);
+ if (DOMAINSET_SUBSET(&empty, &domain->ds_mask))
+ return (true);
+
+ /* Remove empty domains from the set and recompute. */
+ DOMAINSET_NAND(&domain->ds_mask, &empty);
domain->ds_cnt = DOMAINSET_COUNT(&domain->ds_mask);
- max = DOMAINSET_FLS(&domain->ds_mask) + 1;
- for (i = j = 0; i < max; i++) {
+ for (i = j = 0; i < DOMAINSET_FLS(&domain->ds_mask); i++)
if (DOMAINSET_ISSET(i, &domain->ds_mask))
domain->ds_order[j++] = i;
- else if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
- domain->ds_prefer == i && domain->ds_cnt > 1) {
- domain->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
- domain->ds_prefer = -1;
- }
+
+ /* Convert a PREFER policy referencing an empty domain to RR. */
+ if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
+ DOMAINSET_ISSET(domain->ds_prefer, &empty)) {
+ domain->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
+ domain->ds_prefer = -1;
}
- return (DOMAINSET_EMPTY(&domain->ds_mask));
+ return (false);
}
/*
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