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.
Unified · Split
| @@ -39,17 +39,14 @@ extern unsigned char pfnnid_map[PFNNID_MAP_MAX]; · 38 unmodified lines | ||
| 39 | 39 | static inline int pfn_to_nid(unsigned long pfn) |
| 40 | 40 | { |
| 41 | 41 | unsigned int i; |
| 42 | − unsigned char r; | |
| 43 | 42 | |
| 44 | 43 | if (unlikely(pfn_is_io(pfn))) |
| 45 | 44 | return 0; |
| 46 | 45 | |
| 47 | 46 | i = pfn >> PFNNID_SHIFT; |
| 48 | 47 | BUG_ON(i >= ARRAY_SIZE(pfnnid_map)); |
| 49 | − r = pfnnid_map[i]; | |
| 50 | − BUG_ON(r == 0xff); | |
| 51 | 48 | |
| 52 | − return (int)r; | |
| 49 | + return (int)pfnnid_map[i]; | |
| 53 | 50 | } |
| 54 | 51 | |
| 55 | 52 | static inline int pfn_valid(int pfn) |