Messages in this thread | | | From | Pavel Tatashin <> | Date | Fri, 29 Jun 2018 13:07:02 -0400 | Subject | Re: [PATCH v9 2/6] mm: page_alloc: remain memblock_next_valid_pfn() on arm/arm64 |
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On Thu, Jun 28, 2018 at 10:30 PM Jia He <hejianet@gmail.com> wrote: > > Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns > where possible") optimized the loop in memmap_init_zone(). But it causes > possible panic bug. So Daniel Vacek reverted it later. > > But as suggested by Daniel Vacek, it is fine to using memblock to skip > gaps and finding next valid frame with CONFIG_HAVE_ARCH_PFN_VALID. > > On arm and arm64, memblock is used by default. But generic version of > pfn_valid() is based on mem sections and memblock_next_valid_pfn() does > not always return the next valid one but skips more resulting in some > valid frames to be skipped (as if they were invalid). And that's why > kernel was eventually crashing on some !arm machines.
Hi Jia,
Is this a bug? Should we make other arches that support memblock to use memblock_is_map_memory() ? it is more expensive, but if the default is broken, maybe it makes sense to change?
Thank you, Pavel
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