From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:44075) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gz2Qx-0006vC-BA for qemu-devel@nongnu.org; Wed, 27 Feb 2019 11:51:52 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gz2Qo-0004BV-SL for qemu-devel@nongnu.org; Wed, 27 Feb 2019 11:51:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59980) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gz2Qf-00044H-RZ for qemu-devel@nongnu.org; Wed, 27 Feb 2019 11:51:36 -0500 Date: Wed, 27 Feb 2019 16:51:21 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20190227165120.GI2602@work-vm> References: <20190227121052.GD2602@work-vm> <87imx5kwlu.fsf@zen.linaroharston> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <87imx5kwlu.fsf@zen.linaroharston> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] possible ahci/migrate fix List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex =?iso-8859-1?Q?Benn=E9e?= , peter.maydell@linaro.org Cc: qemu-devel@nongnu.org, quintela@redhat.com, peterx@redhat.com * Alex Benn=E9e (alex.bennee@linaro.org) wrote: >=20 > Dr. David Alan Gilbert writes: >=20 > > Hi Alex, > > Can you see if the attached patch fixes the ahci/migrate failure yo= u > > see; it won't fail for me however mean I am to it. >=20 > over 2000 iterations without issue, commit before crashed within 30 >=20 > Tested-by: Alex Benn=E9e Great, just reposted as a proper patch. > How quickly can we get this merged? Once it gets a review-by I'm happy if someone wants to merge it directly given the pain it's causing. Alternatively we'll do a migration pull next week with it. Dave > > > > > > From f4c327d14d656d1c0f0e694d0efc6165493416f0 Mon Sep 17 00:00:00 200= 1 > > From: "Dr. David Alan Gilbert" > > Date: Wed, 27 Feb 2019 12:04:37 +0000 > > Subject: [PATCH] migration: Cleanup during exit > > > > Currently we cleanup the migration object as we exit main after the > > main_loop finishes; however if there's a migration running things > > get messy and we can end up with the migration thread still trying > > to access freed structures. > > > > We now take a ref to the object around the migration thread itself, > > so the act of dropping the ref during exit doesn't cause us to lose > > the state until the thread quits. > > > > Cancelling the migration during migration also tries to get the threa= d > > to quit. > > > > We do this a bit earlier; so hopefully migration gets out of the way > > before all the devices etc are freed. > > > > Signed-off-by: Dr. David Alan Gilbert > > --- > > migration/migration.c | 8 ++++++++ > > vl.c | 7 ++++++- > > 2 files changed, 14 insertions(+), 1 deletion(-) > > > > diff --git a/migration/migration.c b/migration/migration.c > > index e44f77af02..f612313d09 100644 > > --- a/migration/migration.c > > +++ b/migration/migration.c > > @@ -126,6 +126,7 @@ static bool migration_object_check(MigrationState= *ms, Error **errp); > > static int migration_maybe_pause(MigrationState *s, > > int *current_active_state, > > int new_state); > > +static void migrate_fd_cancel(MigrationState *s); > > > > void migration_object_init(void) > > { > > @@ -169,6 +170,11 @@ void migration_object_init(void) > > > > void migration_object_finalize(void) > > { > > + /* > > + * Cancel the current migration - that will (eventually) > > + * stop the migration using this structure > > + */ > > + migrate_fd_cancel(current_migration); > > object_unref(OBJECT(current_migration)); > > } > > > > @@ -3134,6 +3140,7 @@ static void *migration_thread(void *opaque) > > > > rcu_register_thread(); > > > > + object_ref(OBJECT(s)); > > s->iteration_start_time =3D qemu_clock_get_ms(QEMU_CLOCK_REALTIM= E); > > > > qemu_savevm_state_header(s->to_dst_file); > > @@ -3230,6 +3237,7 @@ static void *migration_thread(void *opaque) > > > > trace_migration_thread_after_loop(); > > migration_iteration_finish(s); > > + object_unref(OBJECT(s)); > > rcu_unregister_thread(); > > return NULL; > > } > > diff --git a/vl.c b/vl.c > > index 2f340686a7..c1920165f3 100644 > > --- a/vl.c > > +++ b/vl.c > > @@ -4579,6 +4579,12 @@ int main(int argc, char **argv, char **envp) > > > > gdbserver_cleanup(); > > > > + /* > > + * cleaning up the migration object cancels any existing migrati= on > > + * try to do this early so that it also stops using devices. > > + */ > > + migration_object_finalize(); > > + > > /* No more vcpu or device emulation activity beyond this point *= / > > vm_shutdown(); > > > > @@ -4594,7 +4600,6 @@ int main(int argc, char **argv, char **envp) > > monitor_cleanup(); > > qemu_chr_cleanup(); > > user_creatable_cleanup(); > > - migration_object_finalize(); > > /* TODO: unref root container, check all devices are ok */ > > > > return 0; > > -- > > 2.20.1 >=20 >=20 > -- > Alex Benn=E9e -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK