On 2024-12-19, Petr Mladek <pmladek@xxxxxxxx> wrote: > I do not want to revert everything now just because of theoretical > problems. What would you revert? This has always been an issue for printk(). > Well, it would be nice to document the lock dependency in > Documentation/core-api/printk-formats.rst Yes. If any locking is involved at all, such specifiers should be documented as not safe in NMI context or within printk_cpu_sync blocks. Also, it should be checked if all such locks are raw_spinlock_t. If any other lock type is used, it probably is already generating a lockdep splat since printk() formats records with local interrupts off. Perhaps we should create a kunit that calls printk() for each of the supported specifiers and see if any lockdep splats appear. John
