Chris, in https://lkml.org/lkml/2015/4/17/616 you stated: ">> + alloc_cpumask_var(&watchdog_cpumask_for_smpboot, GFP_KERNEL); > > alloc_cpumask_var could fail? Good catch; if I get a failure I'll just return early without trying to start the watchdog, since clearly things are too memory-constrained to enable that functionality anyway." Let's assume that (in spite of the memory constraints) the kernel would still be able to make progress and get to a point where the system will be usable. In this corner case, the following code would leave a NULL pointer behind in watchdog_cpumask and in watchdog_cpumask_bits which could subsequently lead to a crash. void __init lockup_detector_init(void) { set_sample_period(); + if (!alloc_cpumask_var(&watchdog_cpumask, GFP_KERNEL)) { + pr_err("Failed to allocate cpumask for watchdog"); + return; + } + watchdog_cpumask_bits = cpumask_bits(watchdog_cpumask); For example, proc_watchdog_cpumask() and the change that your patch introduces in watchdog_enable_all_cpus() are not protected against a possible NULL pointer. I think the code needs to be made safer. Regards, Uli -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
