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 #include <linux/slab.h> 36 37 TAILQ_HEAD(, shrinker) lkpi_shrinkers = TAILQ_HEAD_INITIALIZER(lkpi_shrinkers); 38 static struct sx sx_shrinker; 39 40 struct shrinker * 41 linuxkpi_shrinker_alloc(unsigned int flags, const char *fmt, ...) 42 { 43 struct shrinker *shrinker; 44 45 shrinker = kzalloc(sizeof(*shrinker), GFP_KERNEL); 46 if (shrinker == NULL) 47 return (NULL); 48 49 shrinker->flags = flags | SHRINKER_ALLOCATED; 50 shrinker->seeks = DEFAULT_SEEKS; 51 52 return (shrinker); 53 } 54 55 int 56 linuxkpi_register_shrinker(struct shrinker *s) 57 { 58 59 KASSERT(s != NULL, ("NULL shrinker")); 60 KASSERT(s->count_objects != NULL, ("NULL shrinker")); 61 KASSERT(s->scan_objects != NULL, ("NULL shrinker")); 62 sx_xlock(&sx_shrinker); 63 s->flags |= SHRINKER_REGISTERED; 64 TAILQ_INSERT_TAIL(&lkpi_shrinkers, s, next); 65 sx_xunlock(&sx_shrinker); 66 return (0); 67 } 68 69 void 70 linuxkpi_unregister_shrinker(struct shrinker *s) 71 { 72 73 sx_xlock(&sx_shrinker); 74 TAILQ_REMOVE(&lkpi_shrinkers, s, next); 75 s->flags &= ~SHRINKER_REGISTERED; 76 sx_xunlock(&sx_shrinker); 77 } 78 79 void 80 linuxkpi_shrinker_free(struct shrinker *shrinker) 81 { 82 83 if (shrinker->flags & SHRINKER_REGISTERED) 84 unregister_shrinker(shrinker); 85 86 kfree(shrinker); 87 } 88 89 void 90 linuxkpi_synchronize_shrinkers(void) 91 { 92 93 sx_xlock(&sx_shrinker); 94 sx_xunlock(&sx_shrinker); 95 } 96 97 #define SHRINKER_BATCH 512 98 99 static void 100 shrinker_shrink(struct shrinker *s) 101 { 102 struct shrink_control sc; 103 unsigned long can_free; 104 unsigned long batch; 105 unsigned long scanned = 0; 106 unsigned long ret; 107 108 can_free = s->count_objects(s, &sc); 109 if (can_free <= 0) 110 return; 111 112 batch = s->batch ? s->batch : SHRINKER_BATCH; 113 while (scanned <= can_free) { 114 sc.nr_to_scan = batch; 115 ret = s->scan_objects(s, &sc); 116 if (ret == SHRINK_STOP) 117 break; 118 scanned += batch; 119 } 120 } 121 122 static void 123 linuxkpi_vm_lowmem(void *arg __unused, int flags __unused) 124 { 125 struct shrinker *s; 126 127 sx_xlock(&sx_shrinker); 128 TAILQ_FOREACH(s, &lkpi_shrinkers, next) { 129 shrinker_shrink(s); 130 } 131 sx_xunlock(&sx_shrinker); 132 } 133 134 static eventhandler_tag lowmem_tag; 135 136 static void 137 linuxkpi_sysinit_shrinker(void *arg __unused) 138 { 139 140 sx_init(&sx_shrinker, "lkpi-shrinker"); 141 lowmem_tag = EVENTHANDLER_REGISTER(vm_lowmem, linuxkpi_vm_lowmem, 142 NULL, EVENTHANDLER_PRI_FIRST); 143 } 144 145 static void 146 linuxkpi_sysuninit_shrinker(void *arg __unused) 147 { 148 149 sx_destroy(&sx_shrinker); 150 EVENTHANDLER_DEREGISTER(vm_lowmem, lowmem_tag); 151 } 152 153 SYSINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 154 linuxkpi_sysinit_shrinker, NULL); 155 SYSUNINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY, 156 linuxkpi_sysuninit_shrinker, NULL); 157