From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42838) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gAJkK-0007Hd-Bj for qemu-devel@nongnu.org; Wed, 10 Oct 2018 15:02:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gAJkG-000196-PY for qemu-devel@nongnu.org; Wed, 10 Oct 2018 15:02:12 -0400 Date: Wed, 10 Oct 2018 20:01:54 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20181010190153.GC2411@work-vm> References: <20181008160536.6332-1-i.maximets@samsung.com> <20181008160536.6332-2-i.maximets@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181008160536.6332-2-i.maximets@samsung.com> Subject: Re: [Qemu-devel] [RFC 1/2] migration: Stop postcopy fault thread before notifying List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ilya Maximets Cc: "Michael S. Tsirkin" , qemu-devel@nongnu.org, =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Maxime Coquelin , qemu-stable@nongnu.org * Ilya Maximets (i.maximets@samsung.com) wrote: > POSTCOPY_NOTIFY_INBOUND_END handlers will remove userfault fds > from the postcopy_remote_fds array which could be still in > use by the fault thread. Let's stop the thread before > notification to avoid possible accessing wrong memory. OK I think; since this is already in the cleanup we shouldn't be getting faults anyway at that point. Reviewed-by: Dr. David Alan Gilbert > Fixes: 46343570c06e ("vhost+postcopy: Wire up POSTCOPY_END notify") > Cc: qemu-stable@nongnu.org > Signed-off-by: Ilya Maximets > --- > migration/postcopy-ram.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c > index 853d8b32ca..e5c02a32c5 100644 > --- a/migration/postcopy-ram.c > +++ b/migration/postcopy-ram.c > @@ -533,6 +533,12 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) > if (mis->have_fault_thread) { > Error *local_err = NULL; > > + /* Let the fault thread quit */ > + atomic_set(&mis->fault_thread_quit, 1); > + postcopy_fault_thread_notify(mis); > + trace_postcopy_ram_incoming_cleanup_join(); > + qemu_thread_join(&mis->fault_thread); > + > if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_END, &local_err)) { > error_report_err(local_err); > return -1; > @@ -541,11 +547,6 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis) > if (qemu_ram_foreach_migratable_block(cleanup_range, mis)) { > return -1; > } > - /* Let the fault thread quit */ > - atomic_set(&mis->fault_thread_quit, 1); > - postcopy_fault_thread_notify(mis); > - trace_postcopy_ram_incoming_cleanup_join(); > - qemu_thread_join(&mis->fault_thread); > > trace_postcopy_ram_incoming_cleanup_closeuf(); > close(mis->userfault_fd); > -- > 2.17.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK