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 26 27 #include <sys/cdefs.h> 28 #include <sys/param.h> 29 #include <sys/systm.h> 30 #include <sys/kernel.h> 31 #include <sys/queue.h> 32 #include <sys/eventhandler.h> 33 #include <sys/sx.h> 34 35 #include <linux/compat.h> 36 #include <linux/shrinker.h> 37 38 TAILQ_HEAD(, shrinker) lkpi_shrinkers = TAILQ_HEAD_INITIALIZER(lkpi_shrinkers); 39 static struct sx sx_shrinker; 40 41 int 42 linuxkpi_register_shrinker(struct shrinker *s) 43 { 44 45 KASSERT(s != NULL, ("NULL shrinker")); 46 KASSERT(s->count_objects != NULL, ("NULL shrinker")); 47 KASSERT(s->scan_objects != NULL, ("NULL shrinker")); 48 sx_xlock(&sx_shrinker); 49 TAILQ_INSERT_TAIL(&lkpi_shrinkers, s, next); 50 sx_xunlock(&sx_shrinker); 51 return (0); 52 } 53 54 void 55 linuxkpi_unregister_shrinker(struct shrinker *s) 56 { 57 58 sx_xlock(&sx_shrinker); 59 TAILQ_REMOVE(&lkpi_shrinkers, s, next); 60 sx_xunlock(&sx_shrinker); 61 } 62 63 void 64 linuxkpi_synchronize_shrinkers(void) 65 { 66 67 sx_xlock(&sx_shrinker); 68 sx_xunlock(&sx_shrinker); 69 } 70 71 #define SHRINKER_BATCH 512 72 73 static void 74 shrinker_shrink(struct shrinker *s) 75 { 76 struct shrink_control sc; 77 unsigned long can_free; 78 unsigned long batch; 79 unsigned long scanned = 0; 80 unsigned long ret; 81 82 can_free = s->count_objects(s, &sc); 83 if (can_free <= 0) 84 return; 85 86 batch = s->batch ? s->batch : SHRINKER_BATCH; 87 while (scanned <= can_free) { 88 sc.nr_to_scan = batch; 89 ret = s->scan_objects(s, &sc); 90 if (ret == SHRINK_STOP) 91 break; 92 scanned += batch; 93 } 94 } 95 96 static void 97 linuxkpi_vm_lowmem(void *arg __unused) 98 { 99 struct shrinker *s; 100 101 sx_xlock(&sx_shrinker); 102 TAILQ_FOREACH(s, &lkpi_shrinkers, next) { 103 shrinker_shrink(s); 104 } 105 sx_xunlock(&sx_shrinker); 106 } 107 108 static eventhandler_tag lowmem_tag; 109 110 static void 111 linuxkpi_sysinit_shrinker(void *arg __unused) 112 { 113 114 sx_init(&sx_shrinker, "lkpi-shrinker"); 115 lowmem_tag = EVENTHANDLER_REGISTER(vm_lowmem, linuxkpi_vm_lowmem, 116 NULL, EVENTHANDLER_PRI_FIRST); 117 } 118 119 static void 120 linuxkpi_sysuninit_shrinker(void *arg __unused) 121 { 122 123 sx_destroy(&sx_shrinker); 124 EVENTHANDLER_DEREGISTER(vm_lowmem, lowmem_tag); 125 } 126 127 SYSINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 128 linuxkpi_sysinit_shrinker, NULL); 129 SYSUNINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 130 linuxkpi_sysuninit_shrinker, NULL); 131