Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [mm/highmem] 61b205f579: WARNING:at_mm/highmem.c:#__kmap_local_sched_out | Date | Wed, 17 Mar 2021 14:44:41 +0100 |
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On Tue, Mar 16 2021 at 00:37, Ira Weiny wrote: > > I think I see the issue. I think this is an invalid configuration. > > 00:26:43 > grep DEBUG_KMAP config-5.11.0-rc7-00002-g61b205f57991 > CONFIG_DEBUG_KMAP_LOCAL=y > CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y > > 00:26:48 > grep DEBUG_HIGHMEM config-5.11.0-rc7-00002-g61b205f57991 > # CONFIG_DEBUG_HIGHMEM is not set
No. It's valid so you can test that crap on 64bit.
> DEBUG_KMAP_LOCAL causes guard pages to be added to the kmap_ctrl array. But > DEBUG_HIGHMEM is used in __kmap_local_sched_out() to check the guard pages. > > DEBUG_HIGHMEM is supposed to select DEBUG_KMAP_LOCAL... but apparently that > did not happen when this configuration was made. > > I still have not hit this condition in my testing. Could you ensure that > DEBUG_HIGMEM is set and rerun the test to see if I am correct?
Why? The whole point of CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is to allow testing of this kmap_local/atomic stuff w/o HIGHMEM, e.g. on 64 bit.
> Thomas wouldn't the following enable checks make more sense? Or perhaps be > more consistent with the processing of kmap_ctrl?
Neither nor. It's simply required to make DEBUG_KMAP_LOCAL=y && HIGHMEM=n case work.
Please add: Fixes: 0e91a0c6984c ("mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP")
which should have contained exactly that change:
> - if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !(i & 0x01)) { > + if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { > WARN_ON_ONCE(!pte_none(pteval)); > continue; > } > @@ -654,7 +654,7 @@ void __kmap_local_sched_in(void) > int idx; > > /* With debug all even slots are unmapped and act as guard */ > - if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !(i & 0x01)) { > + if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { > WARN_ON_ONCE(!pte_none(pteval)); > continue; > }
Thanks,
tglx
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