4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heinz Mauelshagen <heinzm@xxxxxxxxxx> [ Upstream commit 644e2537fdc77baeeefc829524937bca64329f82 ] When initiating a stripe adding reshape, a deadlock between md_stop_writes() waiting for the sync thread to stop and the running sync thread waiting for inactive stripes occurs (this frequently happens on single-core but rarely on multi-core systems). Fix this deadlock by setting MD_RECOVERY_WAIT to have the main MD resynchronization thread worker (md_do_sync()) bail out when initiating the reshape via constructor arguments. Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/md/dm-raid.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -3869,14 +3869,13 @@ static int rs_start_reshape(struct raid_ struct mddev *mddev = &rs->md; struct md_personality *pers = mddev->pers; + /* Don't allow the sync thread to work until the table gets reloaded. */ + set_bit(MD_RECOVERY_WAIT, &mddev->recovery); + r = rs_setup_reshape(rs); if (r) return r; - /* Need to be resumed to be able to start reshape, recovery is frozen until raid_resume() though */ - if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) - mddev_resume(mddev); - /* * Check any reshape constraints enforced by the personalility * @@ -3900,10 +3899,6 @@ static int rs_start_reshape(struct raid_ } } - /* Suspend because a resume will happen in raid_resume() */ - set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags); - mddev_suspend(mddev); - /* * Now reshape got set up, update superblocks to * reflect the fact so that a table reload will
