xref: /freebsd/sys/kern/kern_mbuf.c (revision 38d120bc13ac1de5b739b67b87016b9122149374)
1 /*-
2  * Copyright (c) 2004, 2005,
3  *	Bosko Milekic <bmilekic@FreeBSD.org>.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice unmodified, this list of conditions and the following
10  *    disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include "opt_param.h"
32 
33 #include <sys/param.h>
34 #include <sys/malloc.h>
35 #include <sys/systm.h>
36 #include <sys/mbuf.h>
37 #include <sys/domain.h>
38 #include <sys/eventhandler.h>
39 #include <sys/kernel.h>
40 #include <sys/protosw.h>
41 #include <sys/smp.h>
42 #include <sys/sysctl.h>
43 
44 #include <security/mac/mac_framework.h>
45 
46 #include <vm/vm.h>
47 #include <vm/vm_extern.h>
48 #include <vm/vm_kern.h>
49 #include <vm/vm_page.h>
50 #include <vm/vm_map.h>
51 #include <vm/uma.h>
52 #include <vm/uma_int.h>
53 #include <vm/uma_dbg.h>
54 
55 /*
56  * In FreeBSD, Mbufs and Mbuf Clusters are allocated from UMA
57  * Zones.
58  *
59  * Mbuf Clusters (2K, contiguous) are allocated from the Cluster
60  * Zone.  The Zone can be capped at kern.ipc.nmbclusters, if the
61  * administrator so desires.
62  *
63  * Mbufs are allocated from a UMA Master Zone called the Mbuf
64  * Zone.
65  *
66  * Additionally, FreeBSD provides a Packet Zone, which it
67  * configures as a Secondary Zone to the Mbuf Master Zone,
68  * thus sharing backend Slab kegs with the Mbuf Master Zone.
69  *
70  * Thus common-case allocations and locking are simplified:
71  *
72  *  m_clget()                m_getcl()
73  *    |                         |
74  *    |   .------------>[(Packet Cache)]    m_get(), m_gethdr()
75  *    |   |             [     Packet   ]            |
76  *  [(Cluster Cache)]   [    Secondary ]   [ (Mbuf Cache)     ]
77  *  [ Cluster Zone  ]   [     Zone     ]   [ Mbuf Master Zone ]
78  *        |                       \________         |
79  *  [ Cluster Keg   ]                      \       /
80  *        |	                         [ Mbuf Keg   ]
81  *  [ Cluster Slabs ]                         |
82  *        |                              [ Mbuf Slabs ]
83  *         \____________(VM)_________________/
84  *
85  *
86  * Whenever an object is allocated with uma_zalloc() out of
87  * one of the Zones its _ctor_ function is executed.  The same
88  * for any deallocation through uma_zfree() the _dtor_ function
89  * is executed.
90  *
91  * Caches are per-CPU and are filled from the Master Zone.
92  *
93  * Whenever an object is allocated from the underlying global
94  * memory pool it gets pre-initialized with the _zinit_ functions.
95  * When the Keg's are overfull objects get decomissioned with
96  * _zfini_ functions and free'd back to the global memory pool.
97  *
98  */
99 
100 int nmbufs;			/* limits number of mbufs */
101 int nmbclusters;		/* limits number of mbuf clusters */
102 int nmbjumbop;			/* limits number of page size jumbo clusters */
103 int nmbjumbo9;			/* limits number of 9k jumbo clusters */
104 int nmbjumbo16;			/* limits number of 16k jumbo clusters */
105 
106 static quad_t maxmbufmem;	/* overall real memory limit for all mbufs */
107 
108 SYSCTL_QUAD(_kern_ipc, OID_AUTO, maxmbufmem, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &maxmbufmem, 0,
109     "Maximum real memory allocatable to various mbuf types");
110 
111 /*
112  * tunable_mbinit() has to be run before any mbuf allocations are done.
113  */
114 static void
115 tunable_mbinit(void *dummy)
116 {
117 	quad_t realmem;
118 
119 	/*
120 	 * The default limit for all mbuf related memory is 1/2 of all
121 	 * available kernel memory (physical or kmem).
122 	 * At most it can be 3/4 of available kernel memory.
123 	 */
124 	realmem = qmin((quad_t)physmem * PAGE_SIZE, vm_kmem_size);
125 	maxmbufmem = realmem / 2;
126 	TUNABLE_QUAD_FETCH("kern.ipc.maxmbufmem", &maxmbufmem);
127 	if (maxmbufmem > realmem / 4 * 3)
128 		maxmbufmem = realmem / 4 * 3;
129 
130 	TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
131 	if (nmbclusters == 0)
132 		nmbclusters = maxmbufmem / MCLBYTES / 4;
133 
134 	TUNABLE_INT_FETCH("kern.ipc.nmbjumbop", &nmbjumbop);
135 	if (nmbjumbop == 0)
136 		nmbjumbop = maxmbufmem / MJUMPAGESIZE / 4;
137 
138 	TUNABLE_INT_FETCH("kern.ipc.nmbjumbo9", &nmbjumbo9);
139 	if (nmbjumbo9 == 0)
140 		nmbjumbo9 = maxmbufmem / MJUM9BYTES / 6;
141 
142 	TUNABLE_INT_FETCH("kern.ipc.nmbjumbo16", &nmbjumbo16);
143 	if (nmbjumbo16 == 0)
144 		nmbjumbo16 = maxmbufmem / MJUM16BYTES / 6;
145 
146 	/*
147 	 * We need at least as many mbufs as we have clusters of
148 	 * the various types added together.
149 	 */
150 	TUNABLE_INT_FETCH("kern.ipc.nmbufs", &nmbufs);
151 	if (nmbufs < nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16)
152 		nmbufs = lmax(maxmbufmem / MSIZE / 5,
153 		    nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16);
154 }
155 SYSINIT(tunable_mbinit, SI_SUB_KMEM, SI_ORDER_MIDDLE, tunable_mbinit, NULL);
156 
157 static int
158 sysctl_nmbclusters(SYSCTL_HANDLER_ARGS)
159 {
160 	int error, newnmbclusters;
161 
162 	newnmbclusters = nmbclusters;
163 	error = sysctl_handle_int(oidp, &newnmbclusters, 0, req);
164 	if (error == 0 && req->newptr && newnmbclusters != nmbclusters) {
165 		if (newnmbclusters > nmbclusters &&
166 		    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
167 			nmbclusters = newnmbclusters;
168 			nmbclusters = uma_zone_set_max(zone_clust, nmbclusters);
169 			EVENTHANDLER_INVOKE(nmbclusters_change);
170 		} else
171 			error = EINVAL;
172 	}
173 	return (error);
174 }
175 SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbclusters, CTLTYPE_INT|CTLFLAG_RW,
176 &nmbclusters, 0, sysctl_nmbclusters, "IU",
177     "Maximum number of mbuf clusters allowed");
178 
179 static int
180 sysctl_nmbjumbop(SYSCTL_HANDLER_ARGS)
181 {
182 	int error, newnmbjumbop;
183 
184 	newnmbjumbop = nmbjumbop;
185 	error = sysctl_handle_int(oidp, &newnmbjumbop, 0, req);
186 	if (error == 0 && req->newptr && newnmbjumbop != nmbjumbop) {
187 		if (newnmbjumbop > nmbjumbop &&
188 		    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
189 			nmbjumbop = newnmbjumbop;
190 			nmbjumbop = uma_zone_set_max(zone_jumbop, nmbjumbop);
191 		} else
192 			error = EINVAL;
193 	}
194 	return (error);
195 }
196 SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbjumbop, CTLTYPE_INT|CTLFLAG_RW,
197 &nmbjumbop, 0, sysctl_nmbjumbop, "IU",
198     "Maximum number of mbuf page size jumbo clusters allowed");
199 
200 static int
201 sysctl_nmbjumbo9(SYSCTL_HANDLER_ARGS)
202 {
203 	int error, newnmbjumbo9;
204 
205 	newnmbjumbo9 = nmbjumbo9;
206 	error = sysctl_handle_int(oidp, &newnmbjumbo9, 0, req);
207 	if (error == 0 && req->newptr && newnmbjumbo9 != nmbjumbo9) {
208 		if (newnmbjumbo9 > nmbjumbo9 &&
209 		    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
210 			nmbjumbo9 = newnmbjumbo9;
211 			nmbjumbo9 = uma_zone_set_max(zone_jumbo9, nmbjumbo9);
212 		} else
213 			error = EINVAL;
214 	}
215 	return (error);
216 }
217 SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbjumbo9, CTLTYPE_INT|CTLFLAG_RW,
218 &nmbjumbo9, 0, sysctl_nmbjumbo9, "IU",
219     "Maximum number of mbuf 9k jumbo clusters allowed");
220 
221 static int
222 sysctl_nmbjumbo16(SYSCTL_HANDLER_ARGS)
223 {
224 	int error, newnmbjumbo16;
225 
226 	newnmbjumbo16 = nmbjumbo16;
227 	error = sysctl_handle_int(oidp, &newnmbjumbo16, 0, req);
228 	if (error == 0 && req->newptr && newnmbjumbo16 != nmbjumbo16) {
229 		if (newnmbjumbo16 > nmbjumbo16 &&
230 		    nmbufs >= nmbclusters + nmbjumbop + nmbjumbo9 + nmbjumbo16) {
231 			nmbjumbo16 = newnmbjumbo16;
232 			nmbjumbo16 = uma_zone_set_max(zone_jumbo16, nmbjumbo16);
233 		} else
234 			error = EINVAL;
235 	}
236 	return (error);
237 }
238 SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbjumbo16, CTLTYPE_INT|CTLFLAG_RW,
239 &nmbjumbo16, 0, sysctl_nmbjumbo16, "IU",
240     "Maximum number of mbuf 16k jumbo clusters allowed");
241 
242 static int
243 sysctl_nmbufs(SYSCTL_HANDLER_ARGS)
244 {
245 	int error, newnmbufs;
246 
247 	newnmbufs = nmbufs;
248 	error = sysctl_handle_int(oidp, &newnmbufs, 0, req);
249 	if (error == 0 && req->newptr && newnmbufs != nmbufs) {
250 		if (newnmbufs > nmbufs) {
251 			nmbufs = newnmbufs;
252 			nmbufs = uma_zone_set_max(zone_mbuf, nmbufs);
253 			EVENTHANDLER_INVOKE(nmbufs_change);
254 		} else
255 			error = EINVAL;
256 	}
257 	return (error);
258 }
259 SYSCTL_PROC(_kern_ipc, OID_AUTO, nmbufs, CTLTYPE_INT|CTLFLAG_RW,
260 &nmbufs, 0, sysctl_nmbufs, "IU",
261     "Maximum number of mbufs allowed");
262 
263 /*
264  * Zones from which we allocate.
265  */
266 uma_zone_t	zone_mbuf;
267 uma_zone_t	zone_clust;
268 uma_zone_t	zone_pack;
269 uma_zone_t	zone_jumbop;
270 uma_zone_t	zone_jumbo9;
271 uma_zone_t	zone_jumbo16;
272 uma_zone_t	zone_ext_refcnt;
273 
274 /*
275  * Local prototypes.
276  */
277 static int	mb_ctor_mbuf(void *, int, void *, int);
278 static int	mb_ctor_clust(void *, int, void *, int);
279 static int	mb_ctor_pack(void *, int, void *, int);
280 static void	mb_dtor_mbuf(void *, int, void *);
281 static void	mb_dtor_clust(void *, int, void *);
282 static void	mb_dtor_pack(void *, int, void *);
283 static int	mb_zinit_pack(void *, int, int);
284 static void	mb_zfini_pack(void *, int);
285 
286 static void	mb_reclaim(void *);
287 static void    *mbuf_jumbo_alloc(uma_zone_t, int, uint8_t *, int);
288 
289 /* Ensure that MSIZE is a power of 2. */
290 CTASSERT((((MSIZE - 1) ^ MSIZE) + 1) >> 1 == MSIZE);
291 
292 /*
293  * Initialize FreeBSD Network buffer allocation.
294  */
295 static void
296 mbuf_init(void *dummy)
297 {
298 
299 	/*
300 	 * Configure UMA zones for Mbufs, Clusters, and Packets.
301 	 */
302 	zone_mbuf = uma_zcreate(MBUF_MEM_NAME, MSIZE,
303 	    mb_ctor_mbuf, mb_dtor_mbuf,
304 #ifdef INVARIANTS
305 	    trash_init, trash_fini,
306 #else
307 	    NULL, NULL,
308 #endif
309 	    MSIZE - 1, UMA_ZONE_MAXBUCKET);
310 	if (nmbufs > 0)
311 		nmbufs = uma_zone_set_max(zone_mbuf, nmbufs);
312 	uma_zone_set_warning(zone_mbuf, "kern.ipc.nmbufs limit reached");
313 
314 	zone_clust = uma_zcreate(MBUF_CLUSTER_MEM_NAME, MCLBYTES,
315 	    mb_ctor_clust, mb_dtor_clust,
316 #ifdef INVARIANTS
317 	    trash_init, trash_fini,
318 #else
319 	    NULL, NULL,
320 #endif
321 	    UMA_ALIGN_PTR, UMA_ZONE_REFCNT);
322 	if (nmbclusters > 0)
323 		nmbclusters = uma_zone_set_max(zone_clust, nmbclusters);
324 	uma_zone_set_warning(zone_clust, "kern.ipc.nmbclusters limit reached");
325 
326 	zone_pack = uma_zsecond_create(MBUF_PACKET_MEM_NAME, mb_ctor_pack,
327 	    mb_dtor_pack, mb_zinit_pack, mb_zfini_pack, zone_mbuf);
328 
329 	/* Make jumbo frame zone too. Page size, 9k and 16k. */
330 	zone_jumbop = uma_zcreate(MBUF_JUMBOP_MEM_NAME, MJUMPAGESIZE,
331 	    mb_ctor_clust, mb_dtor_clust,
332 #ifdef INVARIANTS
333 	    trash_init, trash_fini,
334 #else
335 	    NULL, NULL,
336 #endif
337 	    UMA_ALIGN_PTR, UMA_ZONE_REFCNT);
338 	if (nmbjumbop > 0)
339 		nmbjumbop = uma_zone_set_max(zone_jumbop, nmbjumbop);
340 	uma_zone_set_warning(zone_jumbop, "kern.ipc.nmbjumbop limit reached");
341 
342 	zone_jumbo9 = uma_zcreate(MBUF_JUMBO9_MEM_NAME, MJUM9BYTES,
343 	    mb_ctor_clust, mb_dtor_clust,
344 #ifdef INVARIANTS
345 	    trash_init, trash_fini,
346 #else
347 	    NULL, NULL,
348 #endif
349 	    UMA_ALIGN_PTR, UMA_ZONE_REFCNT);
350 	uma_zone_set_allocf(zone_jumbo9, mbuf_jumbo_alloc);
351 	if (nmbjumbo9 > 0)
352 		nmbjumbo9 = uma_zone_set_max(zone_jumbo9, nmbjumbo9);
353 	uma_zone_set_warning(zone_jumbo9, "kern.ipc.nmbjumbo9 limit reached");
354 
355 	zone_jumbo16 = uma_zcreate(MBUF_JUMBO16_MEM_NAME, MJUM16BYTES,
356 	    mb_ctor_clust, mb_dtor_clust,
357 #ifdef INVARIANTS
358 	    trash_init, trash_fini,
359 #else
360 	    NULL, NULL,
361 #endif
362 	    UMA_ALIGN_PTR, UMA_ZONE_REFCNT);
363 	uma_zone_set_allocf(zone_jumbo16, mbuf_jumbo_alloc);
364 	if (nmbjumbo16 > 0)
365 		nmbjumbo16 = uma_zone_set_max(zone_jumbo16, nmbjumbo16);
366 	uma_zone_set_warning(zone_jumbo16, "kern.ipc.nmbjumbo16 limit reached");
367 
368 	zone_ext_refcnt = uma_zcreate(MBUF_EXTREFCNT_MEM_NAME, sizeof(u_int),
369 	    NULL, NULL,
370 	    NULL, NULL,
371 	    UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
372 
373 	/* uma_prealloc() goes here... */
374 
375 	/*
376 	 * Hook event handler for low-memory situation, used to
377 	 * drain protocols and push data back to the caches (UMA
378 	 * later pushes it back to VM).
379 	 */
380 	EVENTHANDLER_REGISTER(vm_lowmem, mb_reclaim, NULL,
381 	    EVENTHANDLER_PRI_FIRST);
382 }
383 SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbuf_init, NULL);
384 
385 /*
386  * UMA backend page allocator for the jumbo frame zones.
387  *
388  * Allocates kernel virtual memory that is backed by contiguous physical
389  * pages.
390  */
391 static void *
392 mbuf_jumbo_alloc(uma_zone_t zone, int bytes, uint8_t *flags, int wait)
393 {
394 
395 	/* Inform UMA that this allocator uses kernel_map/object. */
396 	*flags = UMA_SLAB_KERNEL;
397 	return ((void *)kmem_alloc_contig(kernel_arena, bytes, wait,
398 	    (vm_paddr_t)0, ~(vm_paddr_t)0, 1, 0, VM_MEMATTR_DEFAULT));
399 }
400 
401 /*
402  * Constructor for Mbuf master zone.
403  *
404  * The 'arg' pointer points to a mb_args structure which
405  * contains call-specific information required to support the
406  * mbuf allocation API.  See mbuf.h.
407  */
408 static int
409 mb_ctor_mbuf(void *mem, int size, void *arg, int how)
410 {
411 	struct mbuf *m;
412 	struct mb_args *args;
413 	int error;
414 	int flags;
415 	short type;
416 
417 #ifdef INVARIANTS
418 	trash_ctor(mem, size, arg, how);
419 #endif
420 	args = (struct mb_args *)arg;
421 	type = args->type;
422 
423 	/*
424 	 * The mbuf is initialized later.  The caller has the
425 	 * responsibility to set up any MAC labels too.
426 	 */
427 	if (type == MT_NOINIT)
428 		return (0);
429 
430 	m = (struct mbuf *)mem;
431 	flags = args->flags;
432 
433 	error = m_init(m, NULL, size, how, type, flags);
434 
435 	return (error);
436 }
437 
438 /*
439  * The Mbuf master zone destructor.
440  */
441 static void
442 mb_dtor_mbuf(void *mem, int size, void *arg)
443 {
444 	struct mbuf *m;
445 	unsigned long flags;
446 
447 	m = (struct mbuf *)mem;
448 	flags = (unsigned long)arg;
449 
450 	KASSERT((m->m_flags & M_NOFREE) == 0, ("%s: M_NOFREE set", __func__));
451 	if ((m->m_flags & M_PKTHDR) && !SLIST_EMPTY(&m->m_pkthdr.tags))
452 		m_tag_delete_chain(m, NULL);
453 #ifdef INVARIANTS
454 	trash_dtor(mem, size, arg);
455 #endif
456 }
457 
458 /*
459  * The Mbuf Packet zone destructor.
460  */
461 static void
462 mb_dtor_pack(void *mem, int size, void *arg)
463 {
464 	struct mbuf *m;
465 
466 	m = (struct mbuf *)mem;
467 	if ((m->m_flags & M_PKTHDR) != 0)
468 		m_tag_delete_chain(m, NULL);
469 
470 	/* Make sure we've got a clean cluster back. */
471 	KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
472 	KASSERT(m->m_ext.ext_buf != NULL, ("%s: ext_buf == NULL", __func__));
473 	KASSERT(m->m_ext.ext_free == NULL, ("%s: ext_free != NULL", __func__));
474 	KASSERT(m->m_ext.ext_arg1 == NULL, ("%s: ext_arg1 != NULL", __func__));
475 	KASSERT(m->m_ext.ext_arg2 == NULL, ("%s: ext_arg2 != NULL", __func__));
476 	KASSERT(m->m_ext.ext_size == MCLBYTES, ("%s: ext_size != MCLBYTES", __func__));
477 	KASSERT(m->m_ext.ext_type == EXT_PACKET, ("%s: ext_type != EXT_PACKET", __func__));
478 	KASSERT(*m->m_ext.ext_cnt == 1, ("%s: ext_cnt != 1", __func__));
479 #ifdef INVARIANTS
480 	trash_dtor(m->m_ext.ext_buf, MCLBYTES, arg);
481 #endif
482 	/*
483 	 * If there are processes blocked on zone_clust, waiting for pages
484 	 * to be freed up, * cause them to be woken up by draining the
485 	 * packet zone.  We are exposed to a race here * (in the check for
486 	 * the UMA_ZFLAG_FULL) where we might miss the flag set, but that
487 	 * is deliberate. We don't want to acquire the zone lock for every
488 	 * mbuf free.
489 	 */
490 	if (uma_zone_exhausted_nolock(zone_clust))
491 		zone_drain(zone_pack);
492 }
493 
494 /*
495  * The Cluster and Jumbo[PAGESIZE|9|16] zone constructor.
496  *
497  * Here the 'arg' pointer points to the Mbuf which we
498  * are configuring cluster storage for.  If 'arg' is
499  * empty we allocate just the cluster without setting
500  * the mbuf to it.  See mbuf.h.
501  */
502 static int
503 mb_ctor_clust(void *mem, int size, void *arg, int how)
504 {
505 	struct mbuf *m;
506 	u_int *refcnt;
507 	int type;
508 	uma_zone_t zone;
509 
510 #ifdef INVARIANTS
511 	trash_ctor(mem, size, arg, how);
512 #endif
513 	switch (size) {
514 	case MCLBYTES:
515 		type = EXT_CLUSTER;
516 		zone = zone_clust;
517 		break;
518 #if MJUMPAGESIZE != MCLBYTES
519 	case MJUMPAGESIZE:
520 		type = EXT_JUMBOP;
521 		zone = zone_jumbop;
522 		break;
523 #endif
524 	case MJUM9BYTES:
525 		type = EXT_JUMBO9;
526 		zone = zone_jumbo9;
527 		break;
528 	case MJUM16BYTES:
529 		type = EXT_JUMBO16;
530 		zone = zone_jumbo16;
531 		break;
532 	default:
533 		panic("unknown cluster size");
534 		break;
535 	}
536 
537 	m = (struct mbuf *)arg;
538 	refcnt = uma_find_refcnt(zone, mem);
539 	*refcnt = 1;
540 	if (m != NULL) {
541 		m->m_ext.ext_buf = (caddr_t)mem;
542 		m->m_data = m->m_ext.ext_buf;
543 		m->m_flags |= M_EXT;
544 		m->m_ext.ext_free = NULL;
545 		m->m_ext.ext_arg1 = NULL;
546 		m->m_ext.ext_arg2 = NULL;
547 		m->m_ext.ext_size = size;
548 		m->m_ext.ext_type = type;
549 		m->m_ext.ext_flags = 0;
550 		m->m_ext.ext_cnt = refcnt;
551 	}
552 
553 	return (0);
554 }
555 
556 /*
557  * The Mbuf Cluster zone destructor.
558  */
559 static void
560 mb_dtor_clust(void *mem, int size, void *arg)
561 {
562 #ifdef INVARIANTS
563 	uma_zone_t zone;
564 
565 	zone = m_getzone(size);
566 	KASSERT(*(uma_find_refcnt(zone, mem)) <= 1,
567 		("%s: refcnt incorrect %u", __func__,
568 		 *(uma_find_refcnt(zone, mem))) );
569 
570 	trash_dtor(mem, size, arg);
571 #endif
572 }
573 
574 /*
575  * The Packet secondary zone's init routine, executed on the
576  * object's transition from mbuf keg slab to zone cache.
577  */
578 static int
579 mb_zinit_pack(void *mem, int size, int how)
580 {
581 	struct mbuf *m;
582 
583 	m = (struct mbuf *)mem;		/* m is virgin. */
584 	if (uma_zalloc_arg(zone_clust, m, how) == NULL ||
585 	    m->m_ext.ext_buf == NULL)
586 		return (ENOMEM);
587 	m->m_ext.ext_type = EXT_PACKET;	/* Override. */
588 #ifdef INVARIANTS
589 	trash_init(m->m_ext.ext_buf, MCLBYTES, how);
590 #endif
591 	return (0);
592 }
593 
594 /*
595  * The Packet secondary zone's fini routine, executed on the
596  * object's transition from zone cache to keg slab.
597  */
598 static void
599 mb_zfini_pack(void *mem, int size)
600 {
601 	struct mbuf *m;
602 
603 	m = (struct mbuf *)mem;
604 #ifdef INVARIANTS
605 	trash_fini(m->m_ext.ext_buf, MCLBYTES);
606 #endif
607 	uma_zfree_arg(zone_clust, m->m_ext.ext_buf, NULL);
608 #ifdef INVARIANTS
609 	trash_dtor(mem, size, NULL);
610 #endif
611 }
612 
613 /*
614  * The "packet" keg constructor.
615  */
616 static int
617 mb_ctor_pack(void *mem, int size, void *arg, int how)
618 {
619 	struct mbuf *m;
620 	struct mb_args *args;
621 	int error, flags;
622 	short type;
623 
624 	m = (struct mbuf *)mem;
625 	args = (struct mb_args *)arg;
626 	flags = args->flags;
627 	type = args->type;
628 
629 #ifdef INVARIANTS
630 	trash_ctor(m->m_ext.ext_buf, MCLBYTES, arg, how);
631 #endif
632 
633 	error = m_init(m, NULL, size, how, type, flags);
634 
635 	/* m_ext is already initialized. */
636 	m->m_data = m->m_ext.ext_buf;
637  	m->m_flags = (flags | M_EXT);
638 
639 	return (error);
640 }
641 
642 int
643 m_pkthdr_init(struct mbuf *m, int how)
644 {
645 #ifdef MAC
646 	int error;
647 #endif
648 	m->m_data = m->m_pktdat;
649 	bzero(&m->m_pkthdr, sizeof(m->m_pkthdr));
650 #ifdef MAC
651 	/* If the label init fails, fail the alloc */
652 	error = mac_mbuf_init(m, how);
653 	if (error)
654 		return (error);
655 #endif
656 
657 	return (0);
658 }
659 
660 /*
661  * This is the protocol drain routine.
662  *
663  * No locks should be held when this is called.  The drain routines have to
664  * presently acquire some locks which raises the possibility of lock order
665  * reversal.
666  */
667 static void
668 mb_reclaim(void *junk)
669 {
670 	struct domain *dp;
671 	struct protosw *pr;
672 
673 	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK | WARN_PANIC, NULL,
674 	    "mb_reclaim()");
675 
676 	for (dp = domains; dp != NULL; dp = dp->dom_next)
677 		for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
678 			if (pr->pr_drain != NULL)
679 				(*pr->pr_drain)();
680 }
681