Commit 18ebc51b3cc3 "Reset Swap when memory is set to unlimited (-1)"
added handling of the case when a user updates the container limits
to set memory to unlimited (-1) but do not set any other limits.
Apparently, in this case, if swap limit was previously set, kernel fails
to set memory.limit_in_bytes to -1 if memory.memsw.limit_in_bytes is
not set to -1.
What the above commit fails to handle correctly is the request when
Memory is set to -1 and MemorySwap is set to some specific limit N
(where N > 0). In this case, the value of N is silently discarded
and MemorySwap is set to -1 instead.
This is wrong thing to do, as the limit set, even if incorrectly,
should not be ignored.
Fix this by only assigning MemorySwap == -1 in case it was not
explicitly set.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
d57f5bb286