On 2024-12-18, Petr Mladek <pmladek@xxxxxxxx> wrote: > My concern is taking a lock when processing a printf format, see > below for more details. Your concern is valid! printk() uses vsnprintf() to format records for the kernel log. printk() may be called from contexts where locking is forbidden (such as NMI). If vsnprintf() can take a lock, then either: vsnprintf() must be made to be lockless or printk() must take another approach to string formatting or we accept that printk() can deadlock for certain format types in certain contexts. John Ogness
