Messages in this thread | | | From | Kalle Valo <> | Subject | Re: [i915] b12d691ea5: kernel_BUG_at_mm/memory.c | Date | Wed, 19 May 2021 18:00:14 +0300 |
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Christoph Hellwig <hch@lst.de> writes:
> On Tue, May 18, 2021 at 04:58:31PM -1000, Linus Torvalds wrote: >> On Tue, May 18, 2021 at 4:26 PM kernel test robot <oliver.sang@intel.com> wrote: >> > >> > commit: b12d691ea5e01db42ccf3b4207e57cb3ce7cfe91 ("i915: fix remap_io_sg to verify the pgprot") >> > [...] >> > [ 778.550996] kernel BUG at mm/memory.c:2183! >> > [ 778.559015] RIP: 0010:remap_pfn_range_notrack >> > (kbuild/src/consumer/mm/memory.c:2183 >> > kbuild/src/consumer/mm/memory.c:2211 >> > kbuild/src/consumer/mm/memory.c:2233 >> > kbuild/src/consumer/mm/memory.c:2255 >> > kbuild/src/consumer/mm/memory.c:2311) >> > [ 778.688951] remap_pfn_range (kbuild/src/consumer/mm/memory.c:2342) >> > [ 778.692700] remap_io_sg (kbuild/src/consumer/drivers/gpu/drm/i915/i915_mm.c:71) i915 >> >> Yeah, so that BUG_ON() checks that theer isn't any old mapping there. >> >> You can't just remap over an old one, but it does seem like that is >> exactly what commit b12d691ea5e0 ("i915: fix remap_io_sg to verify the >> pgprot") ends up doing. >> >> So the code used to just do "apply_to_page_range()", which admittedly >> was odd too. But it didn't mind having old mappings and re-applying >> something over them. >> >> Converting it to use remap_pfn_range() does look better, but it kind >> of depends on it ever being done *once*. But the caller seems to very >> much remap the whole vmsa at fault time, so... >> >> I don't know what the right thing to do here is, because I don't know >> the invalidation logic and when faults happen. >> >> I see that there is another thread about different issues on the >> intel-gfx list. Adding a few people to this kernel test robot thread >> too. >> >> I'd be inclined to revert the commits as "not ready yet", but it would >> be better if somebody can go "yeah, this should be done properly like >> X". > > I think reverting just this commit for now is the best thing.
Yes, please revert it if there's no quick fix. On my Dell XPS 13 9310 laptop (with Debian 10) X won't start until I revert commit b12d691ea5e0, so this is a major issue.
Also adding the new regressions list, as this is an i915 regression introduced in v5.13-rc1.
-- https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
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