b6da0ffb09
pfn_valid() compares the PFN to max_mapnr: __pfn >= min_low_pfn && __pfn < max_mapnr; On HIGHMEM kernels, highend_pfn is used to set the value of max_mapnr. Unfortunately, highend_pfn is left at zero if the system does not actually have enough RAM to reach into the HIGHMEM range. This causes pfn_valid() to always return false, and when debug checks are enabled the kernel will fail catastrophically: Memory: 22432k/32768k available (2249k kernel code, 10336k reserved, 653k data, 1352k init, 0k highmem) NR_IRQS:128 kfree_debugcheck: out of range ptr 81c02900h. Kernel bug detected[#1]: Cpu 0 $ 0 : 00000000 10008400 00000034 00000000 $ 4 : 8003e160 802a0000 8003e160 00000000 $ 8 : 00000000 0000003e 00000747 00000747 ... On such a configuration, max_low_pfn should be used to set max_mapnr. This was seen on 2.6.34. Signed-off-by: Kevin Cernekee <cernekee@gmail.com> To: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/1992/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> |
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Kconfig |