2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> commit 1cc684ab75123efe7ff446eb821d44375ba8fa30 upstream As Tetsuo Handa pointed out, request_module() can stress the system while the oom-killed caller sleeps in TASK_UNINTERRUPTIBLE. The task T uses "almost all" memory, then it does something which triggers request_module(). Say, it can simply call sys_socket(). This in turn needs more memory and leads to OOM. oom-killer correctly chooses T and kills it, but this can't help because it sleeps in TASK_UNINTERRUPTIBLE and after that oom-killer becomes "disabled" by the TIF_MEMDIE task T. Make __request_module() killable. The only necessary change is that call_modprobe() should kmalloc argv and module_name, they can't live in the stack if we use UMH_KILLABLE. This memory is freed via call_usermodehelper_freeinfo()->cleanup. Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> [dannf, bwh: backported to Debian's 2.6.32] Signed-off-by: Willy Tarreau <w@xxxxxx> --- kernel/kmod.c | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) diff --git a/kernel/kmod.c b/kernel/kmod.c index 1088a8f..8ecc509 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -53,16 +53,48 @@ static DECLARE_RWSEM(umhelper_sem); */ char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe"; +static void free_modprobe_argv(char **argv, char **envp) +{ + kfree(argv[3]); /* check call_modprobe() */ + kfree(argv); +} + static int call_modprobe(char *module_name, int wait) { static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL }; + struct subprocess_info *info; + + char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL); + if (!argv) + goto out; - char *argv[] = { modprobe_path, "-q", "--", module_name, NULL }; + module_name = kstrdup(module_name, GFP_KERNEL); + if (!module_name) + goto free_argv; - return call_usermodehelper(modprobe_path, argv, envp, wait); + argv[0] = modprobe_path; + argv[1] = "-q"; + argv[2] = "--"; + argv[3] = module_name; /* check free_modprobe_argv() */ + argv[4] = NULL; + + info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC); + if (!info) + goto free_module_name; + + call_usermodehelper_setcleanup(info, free_modprobe_argv); + + return call_usermodehelper_exec(info, wait | UMH_KILLABLE); + +free_module_name: + kfree(module_name); +free_argv: + kfree(argv); +out: + return -ENOMEM; } /** -- 1.7.12.2.21.g234cd45.dirty -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html