Merge branch 'mptcp-fixes'

Mat Martineau says:

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mptcp: Fixes for buffer reclaim and option writing

Here are three fixes dealing with a syzkaller crash MPTCP triggers in
the memory manager in 5.16-rc8, and some option writing problems.

Patches 1 and 2 fix some corner cases in MPTCP option writing.

Patch 3 addresses a crash that syzkaller found a way to trigger in the mm
subsystem by passing an invalid value to __sk_mem_reduce_allocated().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>