shmem: restrict noswap option to initial user namespace

Prevent tmpfs instances mounted in an unprivileged namespaces from evading
accounting of locked memory by using the "noswap" mount option.

Link: https://lkml.kernel.org/r/20230420-faxen-advokat-40abb4c1a152@brauner
Signed-off-by: Christian Brauner <[email protected]>
Reported-by: Hugh Dickins <[email protected]>
  Link: https://lore.kernel.org/lkml/[email protected]
Reviewed-by: Luis Chamberlain <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Pankaj Raghav <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions