On Tue, Nov 3, 2020 at 10:27 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > kmap_types.h is a misnomer because the old atomic MAP based array does not > exist anymore and the whole indirection of architectures including > kmap_types.h is inconinstent and does not allow to provide guard page > debugging for this misfeature. > > Add a common header file which defines the mapping stack size for all > architectures. Will be used when converting architectures over to a > generic kmap_local/atomic implementation. > > The array size is chosen with the following constraints in mind: > > - The deepest nest level in one context is 3 according to code > inspection. > > - The worst case nesting for the upcoming reemptible version would be: > > 2 maps in task context and a fault inside > 2 maps in the fault handler > 3 maps in softirq > 2 maps in interrupt > > So a total of 16 is sufficient and probably overestimated. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
