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Date:      Tue, 10 Jul 2018 00:18:13 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r336149 - in head/sys: kern vm
Message-ID:  <201807100018.w6A0ID7V058177@repo.freebsd.org>
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Author: markj
Date: Tue Jul 10 00:18:12 2018
New Revision: 336149
URL: https://svnweb.freebsd.org/changeset/base/336149

Log:
  Fix pre-SI_SUB_CPU initialization of per-CPU counters.
  
  r336020 introduced pcpu_page_alloc(), replacing page_alloc() as the
  backend allocator for PCPU UMA zones.  Unlike page_alloc(), it does
  not honour malloc(9) flags such as M_ZERO or M_NODUMP, so fix that.
  
  r336020 also changed counter(9) to initialize each counter using a
  CPU_FOREACH() loop instead of an SMP rendezvous.  Before SI_SUB_CPU,
  smp_rendezvous() will only execute the callback on the current CPU
  (i.e., CPU 0), so only one counter gets zeroed.  The rest are zeroed
  by virtue of the fact that UMA gratuitously zeroes slabs when importing
  them into a zone.
  
  Prior to SI_SUB_CPU, all_cpus is clear, so with r336020 we weren't
  zeroing vm_cnt counters during boot: the CPU_FOREACH() loop had no
  effect, and pcpu_page_alloc() didn't honour M_ZERO.  Fix this by
  iterating over the full range of CPU IDs when zeroing counters,
  ignoring whether the corresponding bits in all_cpus are set.
  
  Reported and tested by:	pho (previous version)
  Reviewed by:		kib (previous version)
  Differential Revision:	https://reviews.freebsd.org/D16190

Modified:
  head/sys/kern/subr_counter.c
  head/sys/vm/uma_core.c

Modified: head/sys/kern/subr_counter.c
==============================================================================
--- head/sys/kern/subr_counter.c	Tue Jul 10 00:01:14 2018	(r336148)
+++ head/sys/kern/subr_counter.c	Tue Jul 10 00:18:12 2018	(r336149)
@@ -43,15 +43,6 @@ __FBSDID("$FreeBSD$");
 #define IN_SUBR_COUNTER_C
 #include <sys/counter.h>
 
-static void
-counter_u64_zero_sync(counter_u64_t c)
-{
-	int cpu;
-
-	CPU_FOREACH(cpu)
-		*(uint64_t*)zpcpu_get_cpu(c, cpu) = 0;
-}
-
 void
 counter_u64_zero(counter_u64_t c)
 {
@@ -69,13 +60,8 @@ counter_u64_fetch(counter_u64_t c)
 counter_u64_t
 counter_u64_alloc(int flags)
 {
-	counter_u64_t r;
 
-	r = uma_zalloc_pcpu(pcpu_zone_64, flags);
-	if (r != NULL)
-		counter_u64_zero_sync(r);
-
-	return (r);
+	return (uma_zalloc_pcpu(pcpu_zone_64, flags | M_ZERO));
 }
 
 void

Modified: head/sys/vm/uma_core.c
==============================================================================
--- head/sys/vm/uma_core.c	Tue Jul 10 00:01:14 2018	(r336148)
+++ head/sys/vm/uma_core.c	Tue Jul 10 00:18:12 2018	(r336149)
@@ -1186,13 +1186,12 @@ pcpu_page_alloc(uma_zone_t zone, vm_size_t bytes, int 
 	struct pcpu *pc;
 #endif
 
-	TAILQ_INIT(&alloctail);
-	MPASS(bytes == (mp_maxid+1)*PAGE_SIZE);
-	*pflag = UMA_SLAB_KERNEL;
+	MPASS(bytes == (mp_maxid + 1) * PAGE_SIZE);
 
+	TAILQ_INIT(&alloctail);
 	flags = VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | VM_ALLOC_NOOBJ |
-		((wait & M_WAITOK) != 0 ? VM_ALLOC_WAITOK :
-		 VM_ALLOC_NOWAIT);
+	    malloc2vm_flags(wait);
+	*pflag = UMA_SLAB_KERNEL;
 	for (cpu = 0; cpu <= mp_maxid; cpu++) {
 		if (CPU_ABSENT(cpu)) {
 			p = vm_page_alloc(NULL, 0, flags);
@@ -2328,10 +2327,10 @@ uma_zalloc_pcpu_arg(uma_zone_t zone, void *udata, int 
 
 	MPASS(zone->uz_flags & UMA_ZONE_PCPU);
 #endif
-	item = uma_zalloc_arg(zone, udata, flags &~ M_ZERO);
+	item = uma_zalloc_arg(zone, udata, flags & ~M_ZERO);
 	if (item != NULL && (flags & M_ZERO)) {
 #ifdef SMP
-		CPU_FOREACH(i)
+		for (i = 0; i <= mp_maxid; i++)
 			bzero(zpcpu_get_cpu(item, i), zone->uz_size);
 #else
 		bzero(item, zone->uz_size);

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