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UMA: Don't destroy zones after the system shutdown process starts.

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Some kernel subsystems, notably ZFS, will destroy UMA zones from a
shutdown eventhandler.  This causes the zone to be drained.  For slabs
that are mapped into KVA this can be very expensive and so it needlessly
delays the shutdown process.

Add a new state to the "booted" variable, BOOT_SHUTDOWN.  Once
kern_reboot() starts invoking shutdown handlers, turn uma_zdestroy()
into a no-op, provided that the zone does not have a custom finalization
routine.

PR:		242427
Reviewed by:	jeff, kib, rlibby
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23066
This commit is contained in:
Mark Johnston 2020-01-09 19:17:42 +00:00
parent d2ccf385fd
commit 860bb7a04c
1 changed files with 30 additions and 11 deletions
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41
sys/vm/uma_core.c
View file

@ -158,8 +158,14 @@ SYSCTL_ULONG(_vm, OID_AUTO, uma_kmem_total, CTLFLAG_RD, &uma_kmem_total, 0,
"UMA kernel memory usage");
/* Is the VM done starting up? */
static enum { BOOT_COLD = 0, BOOT_STRAPPED, BOOT_PAGEALLOC, BOOT_BUCKETS,
BOOT_RUNNING } booted = BOOT_COLD;
static enum {
BOOT_COLD,
BOOT_STRAPPED,
BOOT_PAGEALLOC,
BOOT_BUCKETS,
BOOT_RUNNING,
BOOT_SHUTDOWN,
} booted = BOOT_COLD;
/*
* This is the handle used to schedule events that need to happen
@ -265,6 +271,7 @@ static int hash_expand(struct uma_hash *, struct uma_hash *);
static void hash_free(struct uma_hash *hash);
static void uma_timeout(void *);
static void uma_startup3(void);
static void uma_shutdown(void);
static void *zone_alloc_item(uma_zone_t, void *, int, int);
static void zone_free_item(uma_zone_t, void *, void *, enum zfreeskip);
static int zone_alloc_limit(uma_zone_t zone, int count, int flags);
@ -1408,8 +1415,7 @@ startup_alloc(uma_zone_t zone, vm_size_t bytes, int domain, uint8_t *pflag,
case BOOT_PAGEALLOC:
if (keg->uk_ppera > 1)
break;
case BOOT_BUCKETS:
case BOOT_RUNNING:
default:
#ifdef UMA_MD_SMALL_ALLOC
keg->uk_allocf = (keg->uk_ppera > 1) ?
page_alloc : uma_small_alloc;
@ -2337,7 +2343,7 @@ zone_ctor(void *mem, int size, void *udata, int flags)
(UMA_ZONE_INHERIT | UMA_ZFLAG_INHERIT));
out:
if (__predict_true(booted == BOOT_RUNNING)) {
if (__predict_true(booted >= BOOT_RUNNING)) {
zone_alloc_counters(zone, NULL);
zone_alloc_sysctl(zone, NULL);
} else {
@ -2465,7 +2471,7 @@ zone_foreach(void (*zfunc)(uma_zone_t, void *arg), void *arg)
* threaded, so locking isn't needed. Startup functions
* are allowed to use M_WAITOK.
*/
if (__predict_true(booted == BOOT_RUNNING))
if (__predict_true(booted >= BOOT_RUNNING))
rw_rlock(&uma_rwlock);
LIST_FOREACH(keg, &uma_kegs, uk_link) {
LIST_FOREACH(zone, &keg->uk_zones, uz_link)
@ -2473,7 +2479,7 @@ zone_foreach(void (*zfunc)(uma_zone_t, void *arg), void *arg)
}
LIST_FOREACH(zone, &uma_cachezones, uz_link)
zfunc(zone, arg);
if (__predict_true(booted == BOOT_RUNNING))
if (__predict_true(booted >= BOOT_RUNNING))
rw_runlock(&uma_rwlock);
}
@ -2635,10 +2641,6 @@ uma_startup2(void)
bucket_enable();
}
/*
* Initialize our callout handle
*
*/
static void
uma_startup3(void)
{
@ -2653,6 +2655,16 @@ uma_startup3(void)
callout_init(&uma_callout, 1);
callout_reset(&uma_callout, UMA_TIMEOUT * hz, uma_timeout, NULL);
booted = BOOT_RUNNING;
EVENTHANDLER_REGISTER(shutdown_post_sync, uma_shutdown, NULL,
EVENTHANDLER_PRI_FIRST);
}
static void
uma_shutdown(void)
{
booted = BOOT_SHUTDOWN;
}
static uma_keg_t
@ -2796,6 +2808,13 @@ void
uma_zdestroy(uma_zone_t zone)
{
/*
* Large slabs are expensive to reclaim, so don't bother doing
* unnecessary work if we're shutting down.
*/
if (booted == BOOT_SHUTDOWN &&
zone->uz_fini == NULL && zone->uz_release == zone_release)
return;
sx_slock(&uma_reclaim_lock);
zone_free_item(zones, zone, NULL, SKIP_NONE);
sx_sunlock(&uma_reclaim_lock);