mm, madvise: fail with ENOMEM when splitting vma will hit max_map_count

[mirror_ubuntu-bionic-kernel.git] / Documentation / vm / ksm.txt

diff --git a/Documentation/vm/ksm.txt b/Documentation/vm/ksm.txt
index 0c64a81d6808309e0e9cf6b7e5d7c87647c52299..6b0ca7feb13573b7a40a9f3c7c145304cf158979 100644 (file)
--- a/Documentation/vm/ksm.txt
+++ b/Documentation/vm/ksm.txt
@@ -38,6 +38,10 @@ the range for whenever the KSM daemon is started; even if the range
 cannot contain any pages which KSM could actually merge; even if
 MADV_UNMERGEABLE is applied to a range which was never MADV_MERGEABLE.
 
+If a region of memory must be split into at least one new MADV_MERGEABLE
+or MADV_UNMERGEABLE region, the madvise may return ENOMEM if the process
+will exceed vm.max_map_count (see Documentation/sysctl/vm.txt).
+
 Like other madvise calls, they are intended for use on mapped areas of
 the user address space: they will report ENOMEM if the specified range
 includes unmapped gaps (though working on the intervening mapped areas),