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mips: Optimize max_mapnr init procedure

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max_mapnr defines the upper boundary of the pages space in the system.
Currently in case if HIGHMEM is available it's calculated based on the
upper high memory PFN limit value. Seeing there is a case when it isn't
fully correct let's optimize out the max_mapnr variable initialization
procedure to cover all the handled in the paging_init() method cases:
1. If CPU has DC-aliases, then high memory is unavailable so the PFNs
upper boundary is determined by max_low_pfn.
2. Otherwise if high memory is available, use highend_pfn value
representing the upper high memory PFNs limit.
3. Otherwise no high memory is available so set max_mapnr with the
low-memory upper limit.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
This commit is contained in:
Serge Semin 2023-12-02 14:14:21 +03:00 committed by Thomas Bogendoerfer
parent e1a9ae4573
commit 1c0150229f
1 changed files with 6 additions and 2 deletions
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8
arch/mips/mm/init.c
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@ -421,9 +421,13 @@ void __init paging_init(void)
" %ldk highmem ignored\n",
(highend_pfn - max_low_pfn) << (PAGE_SHIFT - 10));
max_zone_pfns[ZONE_HIGHMEM] = max_low_pfn;
}
max_mapnr = highend_pfn ? highend_pfn : max_low_pfn;
max_mapnr = max_low_pfn;
} else if (highend_pfn) {
max_mapnr = highend_pfn;
} else {
max_mapnr = max_low_pfn;
}
#else
max_mapnr = max_low_pfn;
#endif