mm: clarify __GFP_MEMALLOC usage

It seems that the existing documentation is not explicit about the
expected usage and potential risks enough.  While it is calls out that
users have to free memory when using this flag it is not really apparent
that users have to careful to not deplete memory reserves and that they
should implement some sort of throttling wrt.  freeing process.

This is partly based on Neil's explanation [1].

Let's also call out that a pre allocated pool allocator should be
considered.

[1] http://lkml.kernel.org/r/[email protected]

[[email protected]: coding style fixes]
[[email protected]: update]
  Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: John Hubbard <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions