From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: John David Anglin <dave.anglin@bell.net>
Cc: Helge Deller <deller@gmx.de>,
linux-parisc List <linux-parisc@vger.kernel.org>
Subject: Re: SCSI bug
Date: Sun, 21 Feb 2016 11:07:56 -0800 [thread overview]
Message-ID: <1456081676.2340.10.camel@HansenPartnership.com> (raw)
In-Reply-To: <D14AFC12-8245-4862-9FFA-92A4F114FC41@bell.net>
On Sun, 2016-02-21 at 13:43 -0500, John David Anglin wrote:
> I verified that commit 54efd50bfd873e2dbf784e0b21a8027ba4299a3e in
> linux-block fails to
> boot and commit 41609892701e26724b8617201f43254cadf2e7ae (blk-cgroup:
> Drop unlikely
> before IS_ERR(_OR_NULL)) does boot successfully. Commit
> 41609892701e26724b8617201f43254cadf2e7ae
> is previous commit in tree.
>
> I don't believe that the change can be reverted from Linus' tree as
> this commit allowed other
> stuff to be removed (see second paragraph of commit description).
OK, can you just verify you can boot 4.5-rc5 without the sata_sil24
driver?
My theory, based on what Helge produced is that this commit is building
a large transfer list > 65535 and then splitting it wrongly. I think
the problem is that it's not respecting the DMA boundary, so Helge sees
a transfer size of 69632 which I think slops over on both sides,
requiring 3 segments to describe. However, the merge code thinks we
only need two (because the length is < 2*65536). The reason we only
see this with ATA drivers is because virtually no SCSI drivers set the
DMA boundary. Most ATA drivers require a dma boundary of 65535.
James
next prev parent reply other threads:[~2016-02-21 19:07 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-23 18:00 SCSI bug John David Anglin
2016-02-20 20:13 ` John David Anglin
2016-02-20 20:43 ` John David Anglin
2016-02-20 21:59 ` Helge Deller
2016-02-20 22:52 ` John David Anglin
2016-02-21 2:52 ` John David Anglin
2016-02-21 3:47 ` James Bottomley
2016-02-21 14:45 ` John David Anglin
2016-02-21 18:10 ` James Bottomley
2016-02-21 18:09 ` John David Anglin
2016-02-21 18:13 ` James Bottomley
2016-02-21 18:43 ` John David Anglin
2016-02-21 19:07 ` James Bottomley [this message]
2016-02-21 19:36 ` Helge Deller
2016-02-21 20:28 ` James Bottomley
2016-02-21 21:09 ` John David Anglin
2016-02-21 21:17 ` Helge Deller
2016-02-21 21:49 ` James Bottomley
2016-02-21 22:08 ` John David Anglin
2016-02-22 0:53 ` John David Anglin
2016-02-22 3:24 ` John David Anglin
2016-02-23 3:04 ` John David Anglin
2016-02-23 18:06 ` Helge Deller
2016-02-23 19:10 ` John David Anglin
2016-02-21 20:42 ` John David Anglin
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