Commit dedca635 authored by Potyra, Stefan's avatar Potyra, Stefan Committed by Linus Torvalds

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: b0f205c2 ("mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage")
Signed-off-by: default avatarStefan Potyra <Stefan.Potyra@elektrobit.com>
Reviewed-by: default avatarDaniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c04e32e9
......@@ -797,7 +797,8 @@ SYSCALL_DEFINE1(mlockall, int, flags)
unsigned long lock_limit;
int ret;
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)))
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) ||
flags == MCL_ONFAULT)
return -EINVAL;
if (!can_do_mlock())
......
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