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Date:      Mon, 22 Oct 2018 15:48:07 +0000 (UTC)
From:      Gleb Smirnoff <glebius@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r339596 - head/sys/vm
Message-ID:  <201810221548.w9MFm7P9049319@repo.freebsd.org>
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Author: glebius
Date: Mon Oct 22 15:48:07 2018
New Revision: 339596
URL: https://svnweb.freebsd.org/changeset/base/339596

Log:
  If we lost race or were migrated during bucket allocation for the per-CPU
  cache, then we put new bucket on generic bucket cache. However, code didn't
  honor UMA_ZONE_NOBUCKETCACHE flag, so potentially we could start a cache
  on a zone that clearly forbids that. Fix this.
  
  Reviewed by:	markj

Modified:
  head/sys/vm/uma_core.c

Modified: head/sys/vm/uma_core.c
==============================================================================
--- head/sys/vm/uma_core.c	Mon Oct 22 15:33:05 2018	(r339595)
+++ head/sys/vm/uma_core.c	Mon Oct 22 15:48:07 2018	(r339596)
@@ -2410,6 +2410,7 @@ uma_zalloc_arg(uma_zone_t zone, void *udata, int flags
 	 * the current cache; when we re-acquire the critical section, we
 	 * must detect and handle migration if it has occurred.
 	 */
+zalloc_restart:
 	critical_enter();
 	cpu = curcpu;
 	cache = &zone->uz_cpu[cpu];
@@ -2551,12 +2552,18 @@ zalloc_start:
 		 * initialized bucket to make this less likely or claim
 		 * the memory directly.
 		 */
-		if (cache->uc_allocbucket != NULL ||
-		    (zone->uz_flags & UMA_ZONE_NUMA &&
-		    domain != PCPU_GET(domain)))
-			LIST_INSERT_HEAD(&zdom->uzd_buckets, bucket, ub_link);
-		else
+		if (cache->uc_allocbucket == NULL &&
+		    ((zone->uz_flags & UMA_ZONE_NUMA) == 0 ||
+		    domain == PCPU_GET(domain))) {
 			cache->uc_allocbucket = bucket;
+		} else if ((zone->uz_flags & UMA_ZONE_NOBUCKETCACHE) != 0) {
+			critical_exit();
+			ZONE_UNLOCK(zone);
+			bucket_drain(zone, bucket);
+			bucket_free(zone, bucket, udata);
+			goto zalloc_restart;
+		} else
+			LIST_INSERT_HEAD(&zdom->uzd_buckets, bucket, ub_link);
 		ZONE_UNLOCK(zone);
 		goto zalloc_start;
 	}

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