Hi all,

When I tried to migrate RT-Preempt/linux-mips from 2.6.29.6-rt23 to 2.6.31-rc8, and compile the kernel without PREEMPT_RT. there is a "kernel panic" take place:

... find the frame buffer:start=40000000 input: AT Translated Set 2 keyboard as /class/input/input0 usb 1-1: new high speed USB device using ehci_hcd and address 2 atkbd.c: keyboard reset failed on isa0060/serio1 usb 1-1: configuration #1 chosen from 1 choice usb 2-1: new high speed USB device using ehci_hcd and address 2 usb 2-1: configuration #1 chosen from 1 choice scsi0 : SCSI emulation for USB Mass Storage devices Unhandled kernel unaligned access[#1]: Cpu 0 $ 0 : 0000000000000000 000000001400c4e0 0000000000000018 0000000000000001 $ 4 : ffffffff806175e8 ffffffff806175f0 ffffffffffffffff ffffffff803c9f84 $ 8 : 00000000000028db ffffffff806b0d75 0000000000000018 74735f6d69616c63 $12 : 0000000000000000 ffffffff80205dbc 0000000000000000 98000000be128000 $16 : ffffffff80620780 980000000100a192 0000000000000002 ffffffff80650e50 $20 : ffffffff80650e50 0000000000000006 ffffffff806b84f8 0000000000000001 $24 : 0000000000000028 ffffffff803c9598 $28 : 98000000be04c000 98000000be04fa40 0000000000000003 ffffffff8027dc70 Hi : 000000000000010a Lo : 000000003df58000 epc : ffffffff8027dc70 ____pagevec_lru_add+0x1b4/0x364 Not tainted ra : ffffffff8027dc70 ____pagevec_lru_add+0x1b4/0x364 Status: 1400c4e2 KX SX UX KERNEL EXL Cause : 00008010 BadVA : 980000000100a192 PrId : 00006303 (ICT Loongson-2) Modules linked in: Process swapper (pid: 1, threadinfo=98000000be04c000, task=98000000be04b818, tls=0)Stack : 0000000000000498 0000000000000030 0000000000000440 0000000000000000 980000000100a158 0000000000000000 0000000000020058 0000000000000000 98000000bd00ae30 0000000000000050 ffffffffffffffef ffffffff80651980 0000000000000000 ffffffff80273e2c 0000000000000000 ffffffff80651980 980000000100a158 ffffffff802746f8 0000000000000000 98000000bd00ae30 98000000be04faa8 0000000000000000 98000000bd00ac40 0000000000000000 0000000000001000 0000000000000002 0000000000001000 0000000000000000 00000000003fff77 ffffffff802bee1c 0000000000000000 98000000be436580 98000000be425b00 98000000006f8400 98000000bd0242f8 0000000000000000 0000000000000400 0000000000000001 0000000000001000 ffffffff802c3094 ... Call Trace: [<ffffffff8027dc70>] ____pagevec_lru_add+0x1b4/0x364 [<ffffffff80273e2c>] add_to_page_cache_lru+0x84/0xa8 [<ffffffff802746f8>] find_or_create_page+0x98/0xec [<ffffffff802bee1c>] __getblk+0x12c/0x3d0 [<ffffffff802c3094>] __bread+0x14/0x120 [<ffffffff8030a834>] ext3_fill_super+0x46c/0x17f4 [<ffffffff8029d780>] get_sb_bdev+0x138/0x1bc [<ffffffff8029d2e0>] vfs_kern_mount+0xb8/0x158 [<ffffffff8029d3d8>] do_kern_mount+0x48/0xf8 [<ffffffff802b4fdc>] do_mount+0x6e0/0x764 [<ffffffff802b5100>] SyS_mount+0xa0/0x104 [<ffffffff80658de0>] mount_block_root+0x124/0x2f8 [<ffffffff806591c8>] prepare_namespace+0x198/0x1cc [<ffffffff80658218>] kernel_init+0x120/0x140 [<ffffffff8021233c>] kernel_thread_helper+0x10/0x18

Code: 3c04805b 0c083285 6484f3c8 <d2220000> 34420020 f2220000 10400060 000200 Disabling lock debugging due to kernel taint Kernel panic - not syncing: Attempted to kill init!

Have traced it basically, seems it stopped on SetPageLRU:

mm/swap.c:

___pagevec_lru_add (struct pagevec *pvec, enum lru_list lru) ... VM_BUG_ON(is_unevictable_lru(lru));

for (i = 0; i < pagevec_count(pvec); i++) { struct page *page = pvec->pages[i]; struct zone *pagezone = page_zone(page); int file; int active;

if (pagezone != zone) { if (zone) spin_unlock_irq(&zone->lru_lock); zone = pagezone; spin_lock_irq(&zone->lru_lock); } VM_BUG_ON(PageActive(page)); VM_BUG_ON(PageUnevictable(page)); VM_BUG_ON(PageLRU(page)); SetPageLRU(page); <--------------- active = is_active_lru(lru); file = is_file_lru(lru); if (active) SetPageActive(page); update_page_reclaim_stat(zone, page, file, active); add_page_to_lru_list(zone, page, lru); } if (zone) spin_unlock_irq(&zone->lru_lock); release_pages(pvec->pages, pvec->nr, pvec->cold); pagevec_reinit(pvec); ...

mm/swap.s:

void SetPageLRU(struct page *page) { set_bit(PG_lru, &page->flags); }

include/linux/page-flags.h:

enum pageflags { PG_locked, /* Page is locked. Don't touch. */ ... PG_lru, ...

Not sure why the page address is invalid here? and when i enable PREEMPT_RT or use the original linux-2.6.31-rc8, it boot normally. any good suggestion about it?

Regards, Zhangjin