Messages in this thread Patch in this message | | | Date | Thu, 3 Feb 2022 15:55:22 +0000 | From | John Garry <> | Subject | Re: [PATCH 00/16] scsi: libsas and users: Factor out LLDD TMF code |
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On 03/02/2022 09:44, Damien Le Moal wrote:
Hi Damien,
>>>> [ 385.102073] sas: Enter sas_scsi_recover_host busy: 1 failed: 1 >>>> [ 385.108026] sas: sas_scsi_find_task: aborting task 0x000000007068ed73 >>>> [ 405.561099] pm80xx0:: pm8001_exec_internal_task_abort 757:TMF task
Contrary to mentioning TMF in the log, this is not a TMF but rather an internal abort timing out. I don't think that this should ever happen. This command should just abort pending IO commands in the controller and not send anything to the target. So for this to timeout means a HW fault or driver bug. And I did not touch this code for pm8001.
>>>> timeout. >>>> [ 405.568236] sas: sas_scsi_find_task: task 0x000000007068ed73 is >>>> aborted >>>> [ 405.574930] sas: sas_eh_handle_sas_errors: task 0x000000007068ed73 is >>>> aborted >>>> [ 411.192602] ata21.00: qc timeout (cmd 0xec) >>>> [ 431.672122] pm80xx0:: pm8001_exec_internal_task_abort 757:TMF task >>>> timeout. >>>> [ 431.679282] ata21.00: failed to IDENTIFY (I/O error, err_mask=0x4) >>>> [ 431.685544] ata21.00: revalidation failed (errno=-5) >>>> [ 441.911948] ata21.00: qc timeout (cmd 0xec) >>>> [ 462.391545] pm80xx0:: pm8001_exec_internal_task_abort 757:TMF task >>>> timeout. >>>> [ 462.398696] ata21.00: failed to IDENTIFY (I/O error, err_mask=0x4) >>>> [ 462.404992] ata21.00: revalidation failed (errno=-5) >>>> [ 492.598769] ata21.00: qc timeout (cmd 0xec) >>>> ... >>>>
Do you have a fuller dmesg with my series?
...
>> } >> - res = -TMF_RESP_FUNC_FAILED; >> + res = TMF_RESP_FUNC_FAILED; >> >> That's effectively the same as what I have in this series in >> sas_execute_tmf(). >> >> However your testing is a SATA device, which I'll check further. > This did not help. Still seeing 100% reproducible hangs.
OK, but I think that we should also have this change as the mainline codes looks broken to be begin with:
--->8 ---
[PATCH] scsi: libsas: Handle all errors in sas_scsi_find_task()
LLDD TMFs callbacks may return linux or other error codes instead of TMF codes. This may cause problems in sas_scsi_find_task() -> .lldd_query_task(), as only TMF codes are handled there. As such, we may not return a task_disposition type. Function sas_eh_handle_sas_errors() only handles that type, and may exit error handling early for unrecognised types.
So use TASK_ABORT_FAILED for non-TMF types returned from .lldd_query_task(), on the assumption that the command may still be alive and error handling should be escalated.
Signed-off-by: John Garry <john.garry@huawei.com>
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c index 53d8b7ede0cd..02274f471308 100644 --- a/drivers/scsi/libsas/sas_scsi_host.c +++ b/drivers/scsi/libsas/sas_scsi_host.c @@ -316,8 +316,11 @@ static enum task_disposition sas_scsi_find_task(struct sas_task *task) pr_notice("%s: task 0x%p failed to abort\n", __func__, task); return TASK_ABORT_FAILED; + default: + pr_notice("%s: task 0x%p result code %d not handled, assuming failed\n", + __func__, task, res); + return TASK_ABORT_FAILED; } - } } return res; ---8< ---- > > I did a lot of testing/digging today,
Thanks for the effort!
> and the hang cause seems to be > missing task completions. > At random, a task times out as its completion
That sounds fimilar to my general issue running this driver on an arm64 host...
> does not come, and subsequent abort trial for the task fail, revalidate > fails
I assume SMP IOs fail if revalidation fails - if this is the case, then the controller seems to be in bad state.
> and the device is dropped (capacity goes to 0). But at that point, > doing rmmod/modprobe to reset the device does not work. sync cache > command issued at rmmod time never completes. I end up needing to power > cycle the machine every time... > > No clue about the root cause yet, but it definitely seem to be related > to NCQ/high QD operation. If I force my tests to use non-NCQ commands, > everything is fine and the tests run to completion without any issue. > > I wonder if their is a tag management bug somewhere...
Maybe. Not sure.
On a related point, Hannes' change here could avoid it:
https://lore.kernel.org/linux-scsi/20210222132405.91369-32-hare@suse.de/
> > I did stumble on something very ugly in libsas too: sas_ata_qc_issue() > drops and retake the ata port lock. No other ATA driver do that since > the ata completion also take that lock. The ata port lock is taken > before ata_qc_issue() is called with IRQ disabled (spin_lock_irqsave()). > So doing a spin_unlock()/spin_lock() in sas_ata_qc_issue() (called from > ata_qc_issue()) seems like a very bad idea. I removed that and > everything work the same way (the lld execute does not sleep). But that > did not solve the hang problem.
I would need to check why this is done again. Before my time...
> > Of note is this is all with your libsas patches applied. Without the > patches, I have KASAN screaming at me about use-after-free in completion > context. With your patches, KASAN is silent. > > Another thing: this driver does not allow changing the max qd... Very > annoying. > > echo 1 > /sys/block/sdX/device/queue_depth > > has no effect. QD stays at 32 for an ATA drive. Need to look into that too.
I had a look at this. It seems that we fail in __ata_change_queue_depth() -> ata_scsi_find_dev() returning NULL.
Thanks again for your effort, I will continue to look.
john
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