With CONFIG_DISCONTIGMEM=y and multiple physical memory areas,
cat /proc/kpageflags triggers this kernel bug:
kernel BUG at arch/parisc/include/asm/mmzone.h:50!
CPU: 2 PID: 7848 Comm: cat Tainted: G D W 3.10.0-rc3-64bit #44
IAOQ[0]: kpageflags_read0x128/0x238
IAOQ[1]: kpageflags_read0x12c/0x238
RP(r2): proc_reg_read0xbc/0x130
Backtrace:
[<00000000402ca2d4>] proc_reg_read0xbc/0x130
[<0000000040235bcc>] vfs_read0xc4/0x1d0
[<0000000040235f0c>] SyS_read0x94/0xf0
[<0000000040105fc0>] syscall_exit0x0/0x14
kpageflags_read() walks through the whole memory, even if some memory
areas are physically not available. So, we should better not BUG on an
unavailable pfn in pfn_to_nid() but just return the expected value -1 or
0.
Signed-off-by: Helge Deller <deller@gmx.de>
ae249b5fa2