From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlastimil Babka Subject: Re: [PATCH v2] mm: mlockall error for flag MCL_ONFAULT Date: Mon, 27 May 2019 15:19:44 +0200 Message-ID: <7d5b948d-0253-e73e-980f-f6db5f92b461@suse.cz> References: <20190527070415.GA1658@dhcp22.suse.cz> <20190527075333.GA6339@er01809n.ebgroup.elektrobit.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190527075333.GA6339@er01809n.ebgroup.elektrobit.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: "Potyra, Stefan" , Michal Hocko , Daniel Jordan Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "Jordan, Tobias" , "akpm@linux-foundation.org" , "kirill.shutemov@linux.intel.com" , "linux-api@vger.kernel.org" List-Id: linux-api@vger.kernel.org On 5/27/19 9:53 AM, Potyra, Stefan wrote: > 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 with‐ > out 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. > > Fixes: b0f205c2a308 ("mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage") > Signed-off-by: Stefan Potyra > Reviewed-by: Daniel Jordan > Acked-by: Michal Hocko Acked-by: Vlastimil Babka Thanks, shame we didn't catch it during review. Hope nobody will report a regression. > --- > mm/mlock.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/mlock.c b/mm/mlock.c > index e492a155c51a..03f39cbdd4c4 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -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()) >