We need to check that a pfn is valid before handing it to pfn_to_page() since on low memory systems with CONFIG_HIGHMEM=n it's possible that a pfn may not have a corresponding struct page.
This is in fact the case for one of Alan's machines where some of the EFI boot services pages live in highmem, and running a kernel without CONFIG_HIGHMEM enabled results in the following oops, BUG: unable to handle kernel paging request at f7f1f080 IP: [<c17fba96>] __free_pages_bootmem+0x5a/0xb8 *pdpt = 0000000001887001 *pde = 0000000001984067 *pte = 000000000 0000000 Oops: 0002 [#1] SMP [...] Call Trace: [<c17feacc>] free_bootmem_late+0x2d/0x3d [<c17f1013>] efi_free_boot_services+0x48/0x5b [<c17ddc12>] start_kernel+0x3ad/0x3cf [<c17dd654>] ? set_init_arg+0x49/0x49 [<c17dd380>] i386_start_kernel+0x12e/0x131 Reported-by: Alan Cox <a...@lxorguk.ukuu.org.uk> Cc: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Matt Fleming <matt.flem...@intel.com> --- mm/bootmem.c | 3 +++ mm/nobootmem.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/mm/bootmem.c b/mm/bootmem.c index 90bd3507b413..406e9cb1d58c 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -164,6 +164,9 @@ void __init free_bootmem_late(unsigned long physaddr, unsigned long size) end = PFN_DOWN(physaddr + size); for (; cursor < end; cursor++) { + if (!pfn_valid(cursor)) + continue; + __free_pages_bootmem(pfn_to_page(cursor), 0); totalram_pages++; } diff --git a/mm/nobootmem.c b/mm/nobootmem.c index 04a9d94333a5..afad246688ce 100644 --- a/mm/nobootmem.c +++ b/mm/nobootmem.c @@ -77,6 +77,9 @@ void __init free_bootmem_late(unsigned long addr, unsigned long size) end = PFN_DOWN(addr + size); for (; cursor < end; cursor++) { + if (!pfn_valid(cursor)) + continue; + __free_pages_bootmem(pfn_to_page(cursor), 0); totalram_pages++; } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/