1 /*- 2 * Copyright (c) 2020 Emmanuel Vadot <manu@FreeBSD.org> 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 * 25 * $FreeBSD$ 26 */ 27 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/kernel.h> 35 #include <sys/queue.h> 36 #include <sys/eventhandler.h> 37 #include <sys/mutex.h> 38 39 #include <linux/compat.h> 40 #include <linux/shrinker.h> 41 42 TAILQ_HEAD(, shrinker) lkpi_shrinkers = TAILQ_HEAD_INITIALIZER(lkpi_shrinkers); 43 static struct mtx mtx_shrinker; 44 45 int 46 linuxkpi_register_shrinker(struct shrinker *s) 47 { 48 49 KASSERT(s != NULL, ("NULL shrinker")); 50 KASSERT(s->count_objects != NULL, ("NULL shrinker")); 51 KASSERT(s->scan_objects != NULL, ("NULL shrinker")); 52 mtx_lock(&mtx_shrinker); 53 TAILQ_INSERT_TAIL(&lkpi_shrinkers, s, next); 54 mtx_unlock(&mtx_shrinker); 55 return (0); 56 } 57 58 void 59 linuxkpi_unregister_shrinker(struct shrinker *s) 60 { 61 62 mtx_lock(&mtx_shrinker); 63 TAILQ_REMOVE(&lkpi_shrinkers, s, next); 64 mtx_unlock(&mtx_shrinker); 65 } 66 67 #define SHRINKER_BATCH 512 68 69 static void 70 shrinker_shrink(struct shrinker *s) 71 { 72 struct shrink_control sc; 73 unsigned long can_free; 74 unsigned long batch; 75 unsigned long scanned = 0; 76 unsigned long ret; 77 78 can_free = s->count_objects(s, &sc); 79 if (can_free <= 0) 80 return; 81 82 batch = s->batch ? s->batch : SHRINKER_BATCH; 83 while (scanned <= can_free) { 84 sc.nr_to_scan = batch; 85 ret = s->scan_objects(s, &sc); 86 if (ret == SHRINK_STOP) 87 break; 88 scanned += batch; 89 } 90 } 91 92 static void 93 linuxkpi_vm_lowmem(void *arg __unused) 94 { 95 struct shrinker *s; 96 97 linux_set_current(curthread); 98 mtx_lock(&mtx_shrinker); 99 TAILQ_FOREACH(s, &lkpi_shrinkers, next) { 100 shrinker_shrink(s); 101 } 102 mtx_unlock(&mtx_shrinker); 103 } 104 105 static eventhandler_tag lowmem_tag; 106 107 static void 108 linuxkpi_sysinit_shrinker(void *arg __unused) 109 { 110 111 mtx_init(&mtx_shrinker, "lkpi-shrinker", NULL, MTX_DEF); 112 lowmem_tag = EVENTHANDLER_REGISTER(vm_lowmem, linuxkpi_vm_lowmem, 113 NULL, EVENTHANDLER_PRI_FIRST); 114 } 115 116 static void 117 linuxkpi_sysuninit_shrinker(void *arg __unused) 118 { 119 120 mtx_destroy(&mtx_shrinker); 121 EVENTHANDLER_DEREGISTER(vm_lowmem, lowmem_tag); 122 } 123 124 SYSINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 125 linuxkpi_sysinit_shrinker, NULL); 126 SYSUNINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 127 linuxkpi_sysuninit_shrinker, NULL); 128