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-rw-r--r--Documentation/mm/highmem.rst5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/mm/highmem.rst b/Documentation/mm/highmem.rst
index 71dc09563ff8..e045a4b7b3da 100644
--- a/Documentation/mm/highmem.rst
+++ b/Documentation/mm/highmem.rst
@@ -84,6 +84,11 @@ list shows them in order of preference of use.
be absolutely sure to keep the use of the return address local to the
thread which mapped it.
+ Most code can be designed to use thread local mappings. User should
+ therefore try to design their code to avoid the use of kmap() by mapping
+ pages in the same thread the address will be used and prefer
+ kmap_local_page().
+
Nesting kmap_local_page() and kmap_atomic() mappings is allowed to a certain
extent (up to KMAP_TYPE_NR) but their invocations have to be strictly ordered
because the map implementation is stack based. See kmap_local_page() kdocs