diff options
Diffstat (limited to 'kernel/kmod.c')
| -rw-r--r-- | kernel/kmod.c | 56 |
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) |