On 2022-12-06 08:00:29 [+0100], Fabio M. De Francesco wrote: > diff --git a/Documentation/mm/highmem.rst b/Documentation/mm/highmem.rst > index 0f731d9196b0..9523e92299f6 100644 > --- a/Documentation/mm/highmem.rst > +++ b/Documentation/mm/highmem.rst > @@ -100,10 +101,21 @@ list shows them in order of preference of use. > (included in the "Functions" section) for details on how to manage nested > mappings. > > -* kmap_atomic(). This permits a very short duration mapping of a single > - page. Since the mapping is restricted to the CPU that issued it, it > - performs well, but the issuing task is therefore required to stay on that > - CPU until it has finished, lest some other task displace its mappings. > +* kmap_atomic(). This function has been deprecated; use kmap_local_page(). > + > + NOTE: Conversions to kmap_local_page() must take care to follow the mapping > + restrictions imposed on kmap_local_page(). Furthermore, code between the > + map/unmap operations may implicitly depended on the side effects of > + kmap_atomic(), such as disabling pagefaults, migration, and/or preemption. > + Such conversions should be changed to make explicit calls for those > + requirements. Furthermore, code between the kmap_atomic() and kunmap_atomic() functions may implicitly depended on the side effects of kmap_atomic() namely disabling pagefaults or preemption or both. > + [Legacy documentation] > + > + This permits a very short duration mapping of a single page. Since the > + mapping is restricted to the CPU that issued it, it performs well, but > + the issuing task is therefore required to stay on that CPU until it has > + finished, lest some other task displace its mappings. > > kmap_atomic() may also be used by interrupt contexts, since it does not > sleep and the callers too may not sleep until after kunmap_atomic() is Sebastian
