From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 31 Jul 2017 16:36:23 +0300 From: Mike Rapoport To: Michal Hocko Cc: Andrew Morton , Andrea Arcangeli , "Dr. David Alan Gilbert" , Pavel Emelyanov , linux-mm , lkml , stable@vger.kernel.org Subject: Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone References: <1501136819-21857-1-git-send-email-rppt@linux.vnet.ibm.com> <20170731122204.GB4878@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170731122204.GB4878@dhcp22.suse.cz> Message-Id: <20170731133622.GC28632@rapoport-lnx> Sender: owner-linux-mm@kvack.org List-ID: On Mon, Jul 31, 2017 at 02:22:04PM +0200, Michal Hocko wrote: > On Thu 27-07-17 09:26:59, Mike Rapoport wrote: > > In the non-cooperative userfaultfd case, the process exit may race with > > outstanding mcopy_atomic called by the uffd monitor. Returning -ENOSPC > > instead of -EINVAL when mm is already gone will allow uffd monitor to > > distinguish this case from other error conditions. > > Normally we tend to return ESRCH in such case. ENOSPC sounds rather > confusing... Well, I don't remember why I used ENOSPC in userfault_copy at the first place, but if we are to keep it userfaultfd_zeropage should return the same error... > > Cc: stable@vger.kernel.org > > Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone") > > > > Signed-off-by: Mike Rapoport > > --- > > > > Unfortunately, I've overlooked userfaultfd_zeropage when I updated > > userfaultd_copy :( > > > > fs/userfaultfd.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > > index cadcd12a3d35..2d8c2d848668 100644 > > --- a/fs/userfaultfd.c > > +++ b/fs/userfaultfd.c > > @@ -1643,6 +1643,8 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, > > ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, > > uffdio_zeropage.range.len); > > mmput(ctx->mm); > > + } else { > > + return -ENOSPC; > > } > > if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) > > return -EFAULT; > > -- > > 2.7.4 > > > > -- > > To unsubscribe, send a message with 'unsubscribe linux-mm' in > > the body to majordomo@kvack.org. For more info on Linux MM, > > see: http://www.linux-mm.org/ . > > Don't email: email@kvack.org > > -- > Michal Hocko > SUSE Labs > -- Sincerely yours, Mike. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org