The use of kmap() is being deprecated in favor of kmap_local_page() where it is feasible. The same is true for kmap_atomic(). In file pci/hmm/hmm.c, function hmm_store() test if we are in atomic context and, if so, it calls kmap_atomic(), if not, it calls kmap(). First of all, in_atomic() shouldn't be used in drivers. This macro cannot always detect atomic context; in particular, it cannot know about held spinlocks in non-preemptible kernels. Notwithstanding what it is said above, this code doesn't need to care whether or not it is executing in atomic context. It can simply use kmap_local_page() / kunmap_local() that can instead do the mapping / unmapping regardless of the context. With kmap_local_page(), the mapping is per thread, CPU local and not globally visible. Therefore, hmm_store()() is a function where the use of kmap_local_page() in place of both kmap() and kmap_atomic() is correctly suited. Convert the calls of kmap() / kunmap() and kmap_atomic() / kunmap_atomic() to kmap_local_page() / kunmap_local() and drop the unnecessary tests which test if the code is in atomic context. Link: https://lore.kernel.org/linux-media/20220413225531.9425-1-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Tested-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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