Tejun Heo wrote:
quoted text
> However, there's still remaining issues.  What does happen if you raise
> allocation length and buffersize of the test program to 16?  ie. Change
> 0x0a in cmd[] to 0x10 and increase buffer[10] to buffer[16].

Eek. The process hangs in D state for a good 60 seconds or so.
Caught a trace with sysrq.

<6>a.out         D 00200202     0  7015   3217
<4>       b801fc7c 00200082 b029d5cb 00200202 b04a4c00 b04a4c00 b046ee58 
b0472040
<4>       b24fa000 b24fa140 b17fc040 00000000 b264e000 b801fb80 b264e000 
b01f266c
<4>       b278f800 00200202 b0285eb7 7fffffff 7fffffff b801fc7c b801fc7c 
b035327c
<4>Call Trace:
<4> [<b029d5cb>] ata_scsi_translate+0xd7/0x105
<4> [<b01f266c>] elv_next_request+0xe3/0xf2
<4> [<b0285eb7>] scsi_dispatch_cmd+0x172/0x1aa
<4> [<b035327c>] schedule_timeout+0x13/0x8d
<4> [<b0128830>] del_timer+0x48/0x4e
<4> [<b0352abc>] wait_for_common+0xb2/0x118
<4> [<b011bc10>] default_wake_function+0x0/0x8
<4> [<b01f50d6>] blk_execute_rq+0xa6/0xbc
<4> [<b01f412b>] blk_end_sync_rq+0x0/0x23
<4> [<b0181a14>] bio_add_pc_page+0x23/0x28
<4> [<b0182116>] bio_copy_user+0x116/0x221
<4> [<b0181e5b>] bio_phys_segments+0xe/0x14
<4> [<b01f4253>] blk_rq_bio_prep+0x28/0xa4
<4> [<b01f452a>] blk_rq_append_bio+0x11/0x3a
<4> [<b01f46a0>] blk_rq_map_user+0xfc/0x17f
<4> [<b01f8173>] sg_io+0x20e/0x2f0
<4> [<b01f8408>] scsi_cmd_ioctl+0x1b3/0x34b

When it unhung, this appeared in the logs
ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
ata2.00: cmd a0/01:00:00:10:00/00:00:00:00:00/a0 tag 0 cdb 0x5a data 16 in
          res 40/00:03:00:00:00/00:00:00:00:00/a0 Emask 0x4 (timeout)
ata2.00: status: { DRDY }
ata2: port is slow to respond, please be patient (Status 0xd0)
ata2: device not ready (errno=-16), forcing hardreset
ata2: soft resetting link
ata2.00: configured for UDMA/33
ata2: EH complete

And the app itself outputted:
result 0
check sense data:
72 0b 00 00 00 00 00 0e 09 0c 00 00 00 03 00 00 00 00 00

Daniel
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