On 03/29, Arnd Bergmann wrote: > > On Wed, Mar 29, 2023, at 17:15, Oleg Nesterov wrote: > > > > This look as if access_ok() or __access_ok() doesn't depend on task, but > > this is not true in general. Say, TASK_SIZE_MAX can check is_32bit_task() > > test_thread_flag(TIF_32BIT...) and this uses "current". > > > > Again, we probably do not care, but I don't like the fact task_access_ok() > > looks as if task_access_ok(task) returns the same result as "task" calling > > access_ok(). > > I think the idea of TASK_SIZE_MAX is that it is a compile-time constant and in fact independent of current, while TASK_SIZE > takes TIF_32BIT into account. Say, arch/loongarch defines TASK_SIZE which depends on test_thread_flag(TIF_32BIT_ADDR) but it doesn't define TASK_SIZE_MAX, so __access_ok() will use TASK_SIZE. Oleg.
