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-rw-r--r--kernel/kmod.c56
1 files changed, 25 insertions, 31 deletions
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 563f97e2be36..6d016c5d97c8 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -45,8 +45,6 @@
#include <trace/events/module.h>
-extern int max_threads;
-
#define CAP_BSET (void *)1
#define CAP_PI (void *)2
@@ -56,6 +54,21 @@ static DEFINE_SPINLOCK(umh_sysctl_lock);
static DECLARE_RWSEM(umhelper_sem);
#ifdef CONFIG_MODULES
+/*
+ * Assuming:
+ *
+ * threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
+ * (u64) THREAD_SIZE * 8UL);
+ *
+ * If you need less than 50 threads would mean we're dealing with systems
+ * smaller than 3200 pages. This assuems you are capable of having ~13M memory,
+ * and this would only be an be an upper limit, after which the OOM killer
+ * would take effect. Systems like these are very unlikely if modules are
+ * enabled.
+ */
+#define MAX_KMOD_CONCURRENT 50
+static atomic_t kmod_concurrent_max = ATOMIC_INIT(MAX_KMOD_CONCURRENT);
+static DECLARE_WAIT_QUEUE_HEAD(kmod_wq);
/*
modprobe_path is set via /proc/sys.
@@ -127,11 +140,7 @@ int __request_module(bool wait, const char *fmt, ...)
{
va_list args;
char module_name[MODULE_NAME_LEN];
- unsigned int max_modprobes;
int ret;
- static atomic_t kmod_concurrent = ATOMIC_INIT(0);
-#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
- static int kmod_loop_msg;
/*
* We don't allow synchronous module loading from async. Module
@@ -154,40 +163,25 @@ int __request_module(bool wait, const char *fmt, ...)
if (ret)
return ret;
- /* If modprobe needs a service that is in a module, we get a recursive
- * loop. Limit the number of running kmod threads to max_threads/2 or
- * MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
- * would be to run the parents of this process, counting how many times
- * kmod was invoked. That would mean accessing the internals of the
- * process tables to get the command line, proc_pid_cmdline is static
- * and it is not worth changing the proc code just to handle this case.
- * KAO.
- *
- * "trace the ppid" is simple, but will fail if someone's
- * parent exits. I think this is as good as it gets. --RR
- */
- max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
- atomic_inc(&kmod_concurrent);
- if (atomic_read(&kmod_concurrent) > max_modprobes) {
- /* We may be blaming an innocent here, but unlikely */
- if (kmod_loop_msg < 5) {
- printk(KERN_ERR
- "request_module: runaway loop modprobe %s\n",
- module_name);
- kmod_loop_msg++;
- }
- atomic_dec(&kmod_concurrent);
- return -ENOMEM;
+ if (atomic_dec_if_positive(&kmod_concurrent_max) < 0) {
+ pr_warn_ratelimited("request_module: kmod_concurrent_max (%u) close to 0 (max_modprobes: %u), for module %s, throttling...",
+ atomic_read(&kmod_concurrent_max),
+ MAX_KMOD_CONCURRENT, module_name);
+ wait_event_interruptible(kmod_wq,
+ atomic_dec_if_positive(&kmod_concurrent_max) >= 0);
}
trace_module_request(module_name, wait, _RET_IP_);
ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
- atomic_dec(&kmod_concurrent);
+ atomic_inc(&kmod_concurrent_max);
+ wake_up(&kmod_wq);
+
return ret;
}
EXPORT_SYMBOL(__request_module);
+
#endif /* CONFIG_MODULES */
static void call_usermodehelper_freeinfo(struct subprocess_info *info)