mm/mlock.c: mlockall error for flag MCL_ONFAULT
authorPotyra, Stefan <Stefan.Potyra@elektrobit.com>
Thu, 13 Jun 2019 22:55:55 +0000 (15:55 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 14 Jun 2019 03:34:56 +0000 (17:34 -1000)
commitdedca63504a204dc8410d98883fdc16dffa8cb80
tree9c0cf66ad0333054241acc8bf3c32e32efe25109
parentc04e32e911653442fc834be6e92e072aeebe01a1
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@elektrobit.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mlock.c