mm/mlock.c: mlockall error for flag MCL_ONFAULT
If mlockall() is called with only MCL_ONFAULT as flag, it removes any
previously applied lockings and does nothing else.
This behavior is counter-intuitive and doesn't match the Linux man page.
For mlockall():
EINVAL Unknown flags were specified or MCL_ONFAULT was specified
without either MCL_FUTURE or MCL_CURRENT.
Consequently, return the error EINVAL, if only MCL_ONFAULT is passed.
That way, applications will at least detect that they are calling
mlockall() incorrectly.
Link: http://lkml.kernel.org/r/20190527075333.GA6339@er01809n.ebgroup.elektrobit.com
Fixes: b0f205c2a308 ("mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage")
Signed-off-by: Stefan Potyra <Stefan.Potyra at elektrobit.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan at oracle.com>
Acked-by: Michal Hocko <mhocko at suse.com>
Acked-by: Vlastimil Babka <vbabka at suse.cz>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
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