zero vm_page_t inputs to vm_page_initfake() for predictable results
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Authored by tychon on May 5 2019, 5:28 PM.

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kib

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rS347168: zero inputs to vm_page_initfake() for predictable results

Summary

In r345811 I introduced a bug when I copied the malloc() of the fake-page array from one place to another by omitting the M_ZERO. Put it back in dmar_bus_dmamap_load_phys() and dmar_bus_dmamap_load_buffer() as well as nvdimm_spa_uio() and nvdimm_spa_g_all_unmapped().

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tychon created this revision.May 5 2019, 5:28 PM

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I think that adding M_ZERO in the places were it is missed is better solution. I am not sure that re-initialization case is not used at all. It is supposed to be used when fake pages come from the vm_page_array[], e.g. typically x86 aperture (or BARs) is located in PCI window and we specially cover memory to 4G in vm_page_array[] even if machine has less than 4G. For such persistent fake pages, it is useful to keep all the fields of struct vm_page intact. I believe I once pasted you the change I have in bhyve+DMAR branch which unconditionally initializes holes in phys map as fictitious pages.

tychon updated this revision to Diff 57074.May 5 2019, 8:02 PM

tychon retitled this revision from vm_page_initfake() could do a better job initializing to zero vm_page_t inputs to vm_page_initfake() for predictable results.

tychon edited the summary of this revision. (Show Details)

kib accepted this revision.May 5 2019, 8:11 PM

This revision is now accepted and ready to land.May 5 2019, 8:11 PM

Closed by commit rS347168: zero inputs to vm_page_initfake() for predictable results (authored by tychon). · Explain WhyMay 6 2019, 12:57 AM

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