From: Mike Galbraith Attempts to read() from the non-existent dmesg buffer will return zero and userspace tends to get stuck in a busyloop. So just remove /dev/kmsg altogether if CONFIG_PRINTK=n. Signed-off-by: Mike Galbraith Signed-off-by: Andrew Morton --- fs/proc/Makefile | 3 ++- fs/proc/proc_misc.c | 2 ++ kernel/printk.c | 7 +------ 3 files changed, 5 insertions(+), 7 deletions(-) diff -puN fs/proc/Makefile~remove-the-syslog-interface-when-printk-is-disabled fs/proc/Makefile --- a/fs/proc/Makefile~remove-the-syslog-interface-when-printk-is-disabled +++ a/fs/proc/Makefile @@ -8,8 +8,9 @@ proc-y := nommu.o task_nommu.o proc-$(CONFIG_MMU) := mmu.o task_mmu.o proc-y += inode.o root.o base.o generic.o array.o \ - kmsg.o proc_tty.o proc_misc.o + proc_tty.o proc_misc.o proc-$(CONFIG_PROC_KCORE) += kcore.o proc-$(CONFIG_PROC_VMCORE) += vmcore.o proc-$(CONFIG_PROC_DEVICETREE) += proc_devtree.o +proc-$(CONFIG_PRINTK) += kmsg.o diff -puN fs/proc/proc_misc.c~remove-the-syslog-interface-when-printk-is-disabled fs/proc/proc_misc.c --- a/fs/proc/proc_misc.c~remove-the-syslog-interface-when-printk-is-disabled +++ a/fs/proc/proc_misc.c @@ -696,9 +696,11 @@ void __init proc_misc_init(void) proc_symlink("mounts", NULL, "self/mounts"); /* And now for trickier ones */ +#ifdef CONFIG_PRINTK entry = create_proc_entry("kmsg", S_IRUSR, &proc_root); if (entry) entry->proc_fops = &proc_kmsg_operations; +#endif create_seq_entry("devices", 0, &proc_devinfo_operations); create_seq_entry("cpuinfo", 0, &proc_cpuinfo_operations); #ifdef CONFIG_BLOCK diff -puN kernel/printk.c~remove-the-syslog-interface-when-printk-is-disabled kernel/printk.c --- a/kernel/printk.c~remove-the-syslog-interface-when-printk-is-disabled +++ a/kernel/printk.c @@ -631,12 +631,7 @@ EXPORT_SYMBOL(vprintk); asmlinkage long sys_syslog(int type, char __user *buf, int len) { - return 0; -} - -int do_syslog(int type, char __user *buf, int len) -{ - return 0; + return -ENOSYS; } static void call_console_drivers(unsigned long start, unsigned long end) _