jobacct_gather/common - scale Pss to bytes before comparing with Rss.

Otherwise, when UsePss was set in JobAcctGatherParams, pss was still
holding the parsed value in kilobyes when compared to
prec->tres_data[TRES_ARRAY_MEM].size_read which holds rss in bytes.

Bug 8771

NEWS

@@ -12,6 +12,7 @@ documents those changes that are of interest to users and administrators.
     were not counted against the job's memory allocation on some nodes.
  -- Fix issue with select/cons_tres and the partition limit MaxCpusPerNode where
     the limit was enforced for one less CPU than the configured value.
+ -- jobacct_gather/common - compare Pss to Rss after scaling Pss to Rss units.
 * Changes in Slurm 21.08.3
 ==========================

src/plugins/jobacct_gather/common/common_jag.c

@@ -189,9 +189,10 @@ static int _get_pss(char *proc_smaps_file, jag_prec_t *prec)
         fclose(fp);
         /* Sanity checks */
 
-        if (pss > 0 && prec->tres_data[TRES_ARRAY_MEM].size_read > pss) {
+        if (pss > 0) {
 		pss *= 1024; /* Scale KB to B */
-                prec->tres_data[TRES_ARRAY_MEM].size_read = pss;
+		if (prec->tres_data[TRES_ARRAY_MEM].size_read > pss)
+			prec->tres_data[TRES_ARRAY_MEM].size_read = pss;
         }
 
 	log_flag(JAG, "%s read pss %"PRIu64" for process %s",