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 __FBSDID("$FreeBSD$"); 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/kernel.h> 33 #include <sys/queue.h> 34 #include <sys/eventhandler.h> 35 #include <sys/sx.h> 36 37 #include <linux/compat.h> 38 #include <linux/shrinker.h> 39 40 TAILQ_HEAD(, shrinker) lkpi_shrinkers = TAILQ_HEAD_INITIALIZER(lkpi_shrinkers); 41 static struct sx sx_shrinker; 42 43 int 44 linuxkpi_register_shrinker(struct shrinker *s) 45 { 46 47 KASSERT(s != NULL, ("NULL shrinker")); 48 KASSERT(s->count_objects != NULL, ("NULL shrinker")); 49 KASSERT(s->scan_objects != NULL, ("NULL shrinker")); 50 sx_xlock(&sx_shrinker); 51 TAILQ_INSERT_TAIL(&lkpi_shrinkers, s, next); 52 sx_xunlock(&sx_shrinker); 53 return (0); 54 } 55 56 void 57 linuxkpi_unregister_shrinker(struct shrinker *s) 58 { 59 60 sx_xlock(&sx_shrinker); 61 TAILQ_REMOVE(&lkpi_shrinkers, s, next); 62 sx_xunlock(&sx_shrinker); 63 } 64 65 void 66 linuxkpi_synchronize_shrinkers(void) 67 { 68 69 sx_xlock(&sx_shrinker); 70 sx_xunlock(&sx_shrinker); 71 } 72 73 #define SHRINKER_BATCH 512 74 75 static void 76 shrinker_shrink(struct shrinker *s) 77 { 78 struct shrink_control sc; 79 unsigned long can_free; 80 unsigned long batch; 81 unsigned long scanned = 0; 82 unsigned long ret; 83 84 can_free = s->count_objects(s, &sc); 85 if (can_free <= 0) 86 return; 87 88 batch = s->batch ? s->batch : SHRINKER_BATCH; 89 while (scanned <= can_free) { 90 sc.nr_to_scan = batch; 91 ret = s->scan_objects(s, &sc); 92 if (ret == SHRINK_STOP) 93 break; 94 scanned += batch; 95 } 96 } 97 98 static void 99 linuxkpi_vm_lowmem(void *arg __unused) 100 { 101 struct shrinker *s; 102 103 sx_xlock(&sx_shrinker); 104 TAILQ_FOREACH(s, &lkpi_shrinkers, next) { 105 shrinker_shrink(s); 106 } 107 sx_xunlock(&sx_shrinker); 108 } 109 110 static eventhandler_tag lowmem_tag; 111 112 static void 113 linuxkpi_sysinit_shrinker(void *arg __unused) 114 { 115 116 sx_init(&sx_shrinker, "lkpi-shrinker"); 117 lowmem_tag = EVENTHANDLER_REGISTER(vm_lowmem, linuxkpi_vm_lowmem, 118 NULL, EVENTHANDLER_PRI_FIRST); 119 } 120 121 static void 122 linuxkpi_sysuninit_shrinker(void *arg __unused) 123 { 124 125 sx_destroy(&sx_shrinker); 126 EVENTHANDLER_DEREGISTER(vm_lowmem, lowmem_tag); 127 } 128 129 SYSINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 130 linuxkpi_sysinit_shrinker, NULL); 131 SYSUNINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 132 linuxkpi_sysuninit_shrinker, NULL); 133