Commit a6335fa1 authored by Alexander Sverdlin's avatar Alexander Sverdlin Committed by Ralf Baechle
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MIPS: bootmem: Don't use memory holes for page bitmap

Commit f9a7febd leads to a fact that mapstart and therefore a page bitmap for
bootmem allocator immediately follows initrd_end. This doesn't always work
well on Octeon, where there are holes in PFN ranges (refer to 5b3b1688 and
4MB-aligned PFN allocation). Depending on the inird location it could happen,
that mapstart would be in an area not allocated by plat_mem_setup() in
arch/mips/cavium-octeon/setup.c, but in the alignment hole between initrd and
the next PFN area. Later on this memory will be unconditionally made available
to buddy allocator at the end of free_all_bootmem_core() (mm/bootmem.c).
All of this results in Linux using the memory not designated for Linux in
Octeon's plat_mem_setup(), which in turn means corruption of the memory used
by another OS/baremetal code on the same SoC.

It doesn't look to me as a problem of Octeon platform code, but rather as an
inability of f9a7febd

 to deal correctly with the fragmented memory-mappings.
Proposed fix moves the check for initrd address to the same calculation-loop
in bootmem_init() (arch/mips/kernel/setup.c), which also accounts for kernel
code location. This should result in mapstart located starting from the first
PFN area after kernel code AND initrd.

Signed-off-by: default avatarAlexander Sverdlin <>
Cc: David Daney <>
Cc: Zubair Lutfullah Kakakhel <>
Cc: Huacai Chen <>
Cc: Andreas Herrmann <>
Cc: Joe Perches <>
Cc: Steven J. Hill <>
Cc: Yusuf Khan <>
Cc: Michael Kreuzer <>
Cc: Aaro Koskinen <>

Signed-off-by: default avatarRalf Baechle <>
parent 7928eb03
......@@ -337,6 +337,11 @@ static void __init bootmem_init(void)
min_low_pfn = start;
if (end <= reserved_end)
/* mapstart should be after initrd_end */
if (initrd_end && end <= (unsigned long)PFN_UP(__pa(initrd_end)))
if (start >= mapstart)
mapstart = max(reserved_end, start);
......@@ -366,14 +371,6 @@ static void __init bootmem_init(void)
max_low_pfn = PFN_DOWN(HIGHMEM_START);
* mapstart should be after initrd_end
if (initrd_end)
mapstart = max(mapstart, (unsigned long)PFN_UP(__pa(initrd_end)));
* Initialize the boot-time allocator with low memory only.
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