Hello.
Christian Borntraeger wrote:
I did some printk debugging.
__atapi_pio_bytes is called with bytes=18. That means with 32bit transfers
there is a 2 byte trailing transfer, which triggers this WARN_ON.
Ouch.. that means all that someone issued a multiple segment data
transfer with a 2 byte aligned chunk in the middle.
That is a bit of a suprise because we set blk_queue_dma_alignment to 3 so
the block layer should never hand us an sg list in that form. That means
we've either got a block layer bug or someone somewhere is generating
invalid sg lists internally to libata.
Can you dump qc->cdb[] and see what command is getting issued in the
broken form ?
I instrumented __atapi_pio_bytes to print some variables. This is the dump of
the first two:
[ 1.484730] count: 36 sg->length: 36 qc->cursg_ofs: 0 bytes: 36
[ 1.485709] qc->cdb[]:12000000240000000000000000000000
That works fine.
That's the typical INQUIRY command with 36-byte data length.
[ 1.499843] scsi 1:0:0:0: CD-ROM HL-DT-ST DVDRAM GSA-U10N 1.05 PQ: 0 ANSI: 5
[ 1.508389] count: 18 sg->length: 96 qc->cursg_ofs: 0 bytes: 18
[ 1.509369] qc->cdb[]:03000000600000000000000000000000
That one is broken.
That's the typical REQUEST SENSE command with 18-byte data length.
MBR, Sergei
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