Disable pristine-tar option in gbp.conf, since there is no pristine-tar branch.

[bcachefs-tools-debian] / linux / shrinker.c

diff --git a/linux/shrinker.c b/linux/shrinker.c
index f6c979aa6ae1bf751139ad604c3e56ead7cc777f..ca34ebc7e02f09ef46f0c168b57cc5ade4ac142b 100644 (file)
--- a/linux/shrinker.c
+++ b/linux/shrinker.c
@@ -1,7 +1,10 @@
 
 #include <stdio.h>
+#include <unistd.h>
 
+#include <linux/kthread.h>
 #include <linux/list.h>
+#include <linux/mm.h>
 #include <linux/mutex.h>
 #include <linux/shrinker.h>
 
@@ -10,92 +13,128 @@
 static LIST_HEAD(shrinker_list);
 static DEFINE_MUTEX(shrinker_lock);
 
-int register_shrinker(struct shrinker *shrinker)
+void shrinker_free(struct shrinker *s)
 {
-       mutex_lock(&shrinker_lock);
-       list_add_tail(&shrinker->list, &shrinker_list);
-       mutex_unlock(&shrinker_lock);
-       return 0;
+       if (s->list.next) {
+               mutex_lock(&shrinker_lock);
+               list_del(&s->list);
+               mutex_unlock(&shrinker_lock);
+       }
+       free(s);
 }
 
-void unregister_shrinker(struct shrinker *shrinker)
+struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...)
+{
+       return calloc(sizeof(struct shrinker), 1);
+}
+
+int shrinker_register(struct shrinker *shrinker)
 {
        mutex_lock(&shrinker_lock);
-       list_del(&shrinker->list);
+       list_add_tail(&shrinker->list, &shrinker_list);
        mutex_unlock(&shrinker_lock);
+       return 0;
 }
 
-struct meminfo {
-       u64             total;
-       u64             available;
-};
-
-static u64 parse_meminfo_line(const char *line)
+static void run_shrinkers_allocation_failed(gfp_t gfp_mask)
 {
-       u64 v;
+       struct shrinker *shrinker;
 
-       if (sscanf(line, " %llu kB", &v) < 1)
-               die("sscanf error");
-       return v << 10;
-}
+       mutex_lock(&shrinker_lock);
+       list_for_each_entry(shrinker, &shrinker_list, list) {
+               struct shrink_control sc = { .gfp_mask  = gfp_mask, };
 
-static struct meminfo read_meminfo(void)
-{
-       struct meminfo ret = { 0 };
-       size_t len, n = 0;
-       char *line = NULL;
-       const char *v;
-       FILE *f;
-
-       f = fopen("/proc/meminfo", "r");
-       if (!f)
-               return ret;
-
-       while ((len = getline(&line, &n, f)) != -1) {
-               if ((v = strcmp_prefix(line, "MemTotal:")))
-                       ret.total = parse_meminfo_line(v);
-
-               if ((v = strcmp_prefix(line, "MemAvailable:")))
-                       ret.available = parse_meminfo_line(v);
-       }
+               unsigned long have = shrinker->count_objects(shrinker, &sc);
 
-       fclose(f);
-       free(line);
+               sc.nr_to_scan = have / 8;
 
-       return ret;
+               shrinker->scan_objects(shrinker, &sc);
+       }
+       mutex_unlock(&shrinker_lock);
 }
 
-void run_shrinkers(void)
+void run_shrinkers(gfp_t gfp_mask, bool allocation_failed)
 {
        struct shrinker *shrinker;
-       struct meminfo info;
+       struct sysinfo info;
        s64 want_shrink;
 
+       if (!(gfp_mask & GFP_KERNEL))
+               return;
+
        /* Fast out if there are no shrinkers to run. */
        if (list_empty(&shrinker_list))
                return;
 
-       info = read_meminfo();
-
-       if (info.total && info.available) {
-               want_shrink = (info.total >> 2) - info.available;
+       if (allocation_failed) {
+               run_shrinkers_allocation_failed(gfp_mask);
+               return;
+       }
 
-               if (want_shrink <= 0)
-                       return;
-       } else {
-               /* If we weren't able to read /proc/meminfo, we must be pretty
-                * low: */
+       si_meminfo(&info);
 
-               want_shrink = 8 << 20;
-       }
+       /* Aim for 6% of physical RAM free without anything in swap */
+       want_shrink = (info.totalram >> 4) - info.freeram
+                       + info.totalswap - info.freeswap;
+       if (want_shrink <= 0)
+               return;
 
        mutex_lock(&shrinker_lock);
        list_for_each_entry(shrinker, &shrinker_list, list) {
                struct shrink_control sc = {
-                       .nr_to_scan = want_shrink >> PAGE_SHIFT
+                       .gfp_mask       = gfp_mask,
+                       .nr_to_scan     = want_shrink >> PAGE_SHIFT
                };
 
                shrinker->scan_objects(shrinker, &sc);
        }
        mutex_unlock(&shrinker_lock);
 }
+
+static int shrinker_thread(void *arg)
+{
+       while (!kthread_should_stop()) {
+               struct timespec to;
+               int v;
+
+               clock_gettime(CLOCK_MONOTONIC, &to);
+               to.tv_sec += 1;
+               __set_current_state(TASK_INTERRUPTIBLE);
+               errno = 0;
+               while ((v = READ_ONCE(current->state)) != TASK_RUNNING &&
+                      errno != ETIMEDOUT)
+                       futex(&current->state, FUTEX_WAIT_BITSET|FUTEX_PRIVATE_FLAG,
+                             v, &to, NULL, (uint32_t)~0);
+               if (kthread_should_stop())
+                       break;
+               if (v != TASK_RUNNING)
+                       __set_current_state(TASK_RUNNING);
+               run_shrinkers(GFP_KERNEL, false);
+       }
+
+       return 0;
+}
+
+struct task_struct *shrinker_task;
+
+__attribute__((constructor(103)))
+static void shrinker_thread_init(void)
+{
+       shrinker_task = kthread_run(shrinker_thread, NULL, "shrinkers");
+       BUG_ON(IS_ERR(shrinker_task));
+}
+
+#if 0
+/*
+ * We seem to be hitting a rare segfault when shutting down the shrinker thread.
+ * Disabling this is going to cause some harmless warnings about memory leaks:
+ */
+__attribute__((destructor(103)))
+static void shrinker_thread_exit(void)
+{
+       int ret = kthread_stop(shrinker_task);
+       BUG_ON(ret);
+
+       shrinker_task = NULL;
+}
+#endif