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