From: Chris Wilson <chris@chris-wilson.co.uk>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [bug report] drm/i915: Allow compaction upto SWIOTLB max segment size
Date: Mon, 14 Nov 2016 11:23:59 +0000 [thread overview]
Message-ID: <20161114112359.GD32240@nuc-i3427.alporthouse.com> (raw)
In-Reply-To: <20161114111455.GA13441@mwanda>
On Mon, Nov 14, 2016 at 02:14:56PM +0300, Dan Carpenter wrote:
> Hello Chris Wilson,
>
> The patch 871dfbd67d4e: "drm/i915: Allow compaction upto SWIOTLB max
> segment size" from Oct 11, 2016, leads to the following static
> checker warning:
>
> drivers/gpu/drm/i915/i915_gem.c:2357 i915_gem_object_get_pages_gtt()
> error: we previously assumed 'sg' could be null (see line 2341)
>
> drivers/gpu/drm/i915/i915_gem.c
> 2339 /* Check that the i965g/gm workaround works. */
> 2340 WARN_ON((gfp & __GFP_DMA32) && (last_pfn >= 0x00100000UL));
> 2341 }
> 2342 if (sg) /* loop terminated early; short sg table */
>
> We added a new check for NULL.
>
> 2343 sg_mark_end(sg);
> 2344
> 2345 /* Trim unused sg entries to avoid wasting memory. */
> 2346 i915_sg_trim(st);
> 2347
> 2348 ret = i915_gem_gtt_prepare_pages(obj, st);
> 2349 if (ret)
> 2350 goto err_pages;
>
> but we hit this goto
>
> 2351
> 2352 if (i915_gem_object_needs_bit17_swizzle(obj))
> 2353 i915_gem_object_do_bit_17_swizzle(obj, st);
> 2354
> 2355 return st;
> 2356
> 2357 err_pages:
> 2358 sg_mark_end(sg);
>
> Then don't check here. Also do we really need to sg_mark_end() twice?
We need the mark_end when escaping from the loop, but after the loop, sg
may be NULL.
Archaelogy, suggests commit e227330223a7 ("drm/i915: avoid leaking DMA
mappings") as the original culprit (i.e. the introduction of goto
err_pages after the loop).
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2016-11-14 11:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-14 11:14 [bug report] drm/i915: Allow compaction upto SWIOTLB max segment size Dan Carpenter
2016-11-14 11:23 ` Chris Wilson [this message]
2016-11-14 11:29 ` [PATCH] drm/i915: Don't touch NULL sg on i915_gem_object_get_pages_gtt() error Chris Wilson
2016-11-14 11:29 ` Chris Wilson
2016-11-18 17:19 ` [Intel-gfx] " Matthew Auld
2016-11-18 17:19 ` Matthew Auld
2016-11-18 20:52 ` [Intel-gfx] " Chris Wilson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161114112359.GD32240@nuc-i3427.alporthouse.com \
--to=chris@chris-wilson.co.uk \
--cc=dan.carpenter@oracle.com \
--cc=intel-gfx@lists.freedesktop.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.