On Thu, 2013-01-10 at 15:56 +0100, Martin Svec wrote: > Dne 9.1.2013 5:19, Nicholas A. Bellinger napsal(a): > > On Tue, 2013-01-08 at 19:56 -0800, Roland Dreier wrote: > >> On Tue, Jan 8, 2013 at 7:48 PM, Nicholas A. Bellinger > >> <nab@xxxxxxxxxxxxxxx> wrote: > >>> Digging into this a bit more, I'm starting to think the root problem is > >>> that the CMD_T_ACTIVE bit in se_cmd->transport_state is getting cleared > >>> by transport_cmd_check_stop() during transport_generic_new_cmd() for > >>> pending WRITEs before the cmd->se_tfo->write_pending() callback occurs, > >>> but is not getting reset until way too late in target_complete_cmd(). > >>> > >>> This bit used to be set each time in transport_add_cmd_to_queue() when a > >>> se_cmd was added to the legacy transport_processing_thread() logic > >>> (including for iSCSI WRITEs), but this has since been removed starting > >>> from v3.6 code. (Here is the v3.5.x reference for good measure) > >>> > >>> http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=blob;f=drivers/target/target_core_transport.c;h=0981707216b7f937db1b7a6931b9df113048ecef;hb=refs/heads/linux-3.5.y#l600 > >>> > >>> So here is a quick patch to explicitly re-set CMD_T_ACTIVE within > >>> target_execute_cmd(), which is the function that iscsi-target now calls > >>> in >= v3.6.x to submit individual WRITEs once the full data payload has > >>> been received. > >>> > >>> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c > >>> index 978762d..1689c8b 100644 > >>> --- a/drivers/target/target_core_transport.c > >>> +++ b/drivers/target/target_core_transport.c > >>> @@ -1687,6 +1687,7 @@ void target_execute_cmd(struct se_cmd *cmd) > >>> return; > >>> } > >>> > >>> + cmd->transport_state |= CMD_T_ACTIVE; > >>> cmd->t_state = TRANSPORT_PROCESSING; > >>> spin_unlock_irq(&cmd->t_state_lock); > >> Yes, I sent the same patch last week. > > <nod>, sorry still catching up on the backlog + busy on WIP v3.9 > > iSER-target bits. ;) > > > >> Not sure if it fixes the crash in this mail thread, but see > >> http://permalink.gmane.org/gmane.linux.scsi/79495 (or your backlog of > >> target-devel mail) for a detailed explanation of another reason why > >> it's needed. > > I'm quite certain at this point that Martin's active I/O shutdown OOPsen > > here is due to the same >= v3.6 regression bug of CMD_T_ACTIVE not being > > re-set during pending WRITEs I/O submission. > > > > So that said, I'll finish catching up tomorrow and end up applying your > > patch as the proper fix for mainline. > > > > Thanks Roland! > > > > --nab > > > > I applied the patch to v3.7.1 and got no oopses after two hours of > testing. I'll give it few more hours > to be sure but the regression bug seems to be fixed. > > Thanks Roland and Nick > Thanks for the update. Applying the bugfix to target-pending/master w/ a CC' to stable now. Thanks Martin & Roland! --nab -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
