lockdep warning inside ide/bio

lockdep warning inside ide/bio

[Dmitry Baryshkov]

Hi,

After 88c381bf09d7b3f2c2e8749150087aff2c434be4 soon after rootfs is
mounted I'm getting the following lockdep trace (the machine in
question is my tosa, booted from CF card with ide-cs driver).

------------[ cut here ]------------
WARNING: at /home/lumag/tosa-tree/kernel/lockdep.c:2195 trace_hardirqs_on_caller+0xf0/0x170()
Modules linked in:
[<c0029fe4>] (dump_stack+0x0/0x14) from [<c003fc40>] (warn_on_slowpath+0x4c/0x84)
[<c003fbf4>] (warn_on_slowpath+0x0/0x84) from [<c00629ac>] (trace_hardirqs_on_caller+0xf0/0x170)
 r6:c0062a40 r5:00000001 r4:c381b080
[<c00628bc>] (trace_hardirqs_on_caller+0x0/0x170) from [<c0062a40>] (trace_hardirqs_on+0x14/0x18)
 r6:00000092 r5:00000000 r4:c3412b30
[<c0062a2c>] (trace_hardirqs_on+0x0/0x18) from [<c03172b0>] (_spin_unlock_irq+0x30/0x60)
[<c0317280>] (_spin_unlock_irq+0x0/0x60) from [<c002c3f4>] (__flush_dcache_aliases+0xec/0xf8)
 r4:c3412b50
[<c002c308>] (__flush_dcache_aliases+0x0/0xf8) from [<c002c474>] (flush_dcache_page+0x74/0x9c)
[<c002c400>] (flush_dcache_page+0x0/0x9c) from [<c008f958>] (copy_to_high_bio_irq+0x64/0xb0)
 r5:c386d668 r4:c3a2b000
[<c008f8f4>] (copy_to_high_bio_irq+0x0/0xb0) from [<c008fe54>] (__bounce_end_io_read+0x34/0x48)
[<c008fe20>] (__bounce_end_io_read+0x0/0x48) from [<c008fe84>] (bounce_end_io_read_isa+0x1c/0x24)
 r6:c39b9658 r5:00000000 r4:c387f448
[<c008fe68>] (bounce_end_io_read_isa+0x0/0x24) from [<c00c7624>] (bio_endio+0x54/0x58)
[<c00c75d0>] (bio_endio+0x0/0x58) from [<c012cbf4>] (req_bio_endio+0xac/0xd0)
[<c012cb48>] (req_bio_endio+0x0/0xd0) from [<c012cdb8>] (__end_that_request_first+0x1a0/0x2f0)
 r5:00011400 r4:c387f448
[<c012cc18>] (__end_that_request_first+0x0/0x2f0) from [<c012d60c>] (__blk_end_request+0x28/0x54)
[<c012d5e4>] (__blk_end_request+0x0/0x54) from [<c01bd024>] (__ide_end_request+0x94/0xc4)
 r5:c39ca0c0 r4:c39ca0c0
[<c01bcf90>] (__ide_end_request+0x0/0xc4) from [<c01bd140>] (ide_end_request+0x68/0x88)
 r4:00011400
[<c01bd0d8>] (ide_end_request+0x0/0x88) from [<c01c2da4>] (task_end_request+0x5c/0x70)
 r7:00000000 r6:c39b9658 r5:00000050 r4:c39ca0c0
[<c01c2d48>] (task_end_request+0x0/0x70) from [<c01c33a4>] (task_in_intr+0xa4/0xd4)
 r5:00000000 r4:c39ca0c0
[<c01c3300>] (task_in_intr+0x0/0xd4) from [<c01bdda0>] (ide_intr+0x10c/0x184)
 r7:40000193 r6:c39ca0c0 r5:c3987938 r4:00000055
[<c01bdc94>] (ide_intr+0x0/0x184) from [<c00717c4>] (handle_IRQ_event+0x2c/0x70)
[<c0071798>] (handle_IRQ_event+0x0/0x70) from [<c0072db0>] (handle_edge_irq+0xf8/0x180)
 r7:c0421314 r6:c3a328a0 r5:00000055 r4:c04212e4
[<c0072cb8>] (handle_edge_irq+0x0/0x180) from [<c0032984>] (pxa_gpio_demux_handler+0x94/0xe0)
 r8:c381d958 r7:c04400b0 r6:f2e00000 r5:00000fe0 r4:00000015
[<c00328f0>] (pxa_gpio_demux_handler+0x0/0xe0) from [<c0025048>] (__exception_text_start+0x48/0x64)
[<c0025000>] (__exception_text_start+0x0/0x64) from [<c0025828>] (__irq_svc+0x48/0xf0)
Exception stack(0xc381d9b8 to 0xc381da00)
d9a0:                                                       00000001 c381b3d0 
d9c0: 00000001 20000113 c042da70 c381da9c c08690d4 c381daa4 00000002 00000004 
d9e0: c00756d0 c381da14 c381d9b0 c381da00 c00627e0 c03172bc 20000113 ffffffff 
 r6:00000400 r5:f2d00000 r4:ffffffff
[<c0317280>] (_spin_unlock_irq+0x0/0x60) from [<c012e5fc>] (generic_unplug_device+0x38/0x3c)
 r4:c3a30a80
[<c012e5c4>] (generic_unplug_device+0x0/0x3c) from [<c012c56c>] (blk_unplug+0x1c/0x20)
 r4:c381da9c
[<c012c550>] (blk_unplug+0x0/0x20) from [<c012c584>] (blk_backing_dev_unplug+0x14/0x18)
[<c012c570>] (blk_backing_dev_unplug+0x0/0x18) from [<c00c2290>] (block_sync_page+0x50/0x58)
[<c00c2240>] (block_sync_page+0x0/0x58) from [<c007571c>] (sync_page+0x4c/0x5c)
[<c00756d0>] (sync_page+0x0/0x5c) from [<c0315170>] (__wait_on_bit_lock+0x60/0x94)
[<c0315110>] (__wait_on_bit_lock+0x0/0x94) from [<c00756a8>] (__lock_page+0x68/0x78)
[<c0075640>] (__lock_page+0x0/0x78) from [<c0075904>] (find_lock_page+0x64/0x94)
 r6:000000a2 r5:c3412b20 r4:c07fa480
[<c00758a0>] (find_lock_page+0x0/0x94) from [<c00781e4>] (filemap_fault+0x1cc/0x39c)
 r6:c3412b20 r5:00000000 r4:00000000
[<c0078018>] (filemap_fault+0x0/0x39c) from [<c0084df4>] (__do_fault+0x54/0x428)
[<c0084da0>] (__do_fault+0x0/0x428) from [<c0085214>] (do_linear_fault+0x4c/0x54)
[<c00851c8>] (do_linear_fault+0x0/0x54) from [<c0086414>] (handle_mm_fault+0x118/0x310)
[<c00862fc>] (handle_mm_fault+0x0/0x310) from [<c002b840>] (__do_page_fault+0x78/0x108)
[<c002b7c8>] (__do_page_fault+0x0/0x108) from [<c002ba98>] (do_page_fault+0xa4/0x164)
[<c002b9f4>] (do_page_fault+0x0/0x164) from [<c002bbf4>] (do_translation_fault+0x18/0x80)
[<c002bbdc>] (do_translation_fault+0x0/0x80) from [<c00251bc>] (do_DataAbort+0x3c/0xa0)
 r5:c0412620 r4:ffffffff
[<c0025180>] (do_DataAbort+0x0/0xa0) from [<c00257cc>] (__dabt_svc+0x4c/0x60)
Exception stack(0xc381dd30 to 0xc381dd78)
dd20:                                     000b2e28 000001d0 00000000 00000000 
dd40: 000b2e28 000c38cc c3a2cc50 00000000 c39e9d08 00000000 c3a2cc88 c381dd8c 
dd60: 00000000 c381dd78 c00d1700 c0134788 20000013 ffffffff                   
 r8:c39e9d08 r7:00000000 r6:c3a2cc50 r5:c381dd64 r4:ffffffff
[<c00d16bc>] (padzero+0x0/0x5c) from [<c00d2bb8>] (load_elf_binary+0x974/0xce0)
[<c00d2244>] (load_elf_binary+0x0/0xce0) from [<c00a2420>] (search_binary_handler+0xf8/0x2ac)
[<c00a2328>] (search_binary_handler+0x0/0x2ac) from [<c00d158c>] (load_script+0x204/0x218)
[<c00d1388>] (load_script+0x0/0x218) from [<c00a2420>] (search_binary_handler+0xf8/0x2ac)
 r6:c3a2cc88 r5:c04256a4 r4:00000000
[<c00a2328>] (search_binary_handler+0x0/0x2ac) from [<c00a3654>] (do_execve+0x138/0x1d0)
[<c00a351c>] (do_execve+0x0/0x1d0) from [<c0029094>] (kernel_execve+0x40/0x88)
[<c0029054>] (kernel_execve+0x0/0x88) from [<c00253c0>] (run_init_process+0x20/0x2c)
 r7:00000000 r6:00000000 r5:00000000 r4:c043fd14
[<c00253a0>] (run_init_process+0x0/0x2c) from [<c0025470>] (init_post+0xa4/0x108)
[<c00253cc>] (init_post+0x0/0x108) from [<c0008a88>] (kernel_init+0x78/0x90)
 r4:c043fd18
[<c0008a10>] (kernel_init+0x0/0x90) from [<c0043520>] (do_exit+0x0/0x2dc)
 r4:00000000
---[ end trace 574432789d45c513 ]---

-- 
With best wishes
Dmitry

Re: lockdep warning inside ide/bio

[James Bottomley]

lockdep people cc'd, thread is at

http://marc.info/?l=linux-ide&m=122288193424170

On Wed, 2008-10-01 at 21:21 +0400, Dmitry Baryshkov wrote:
> After 88c381bf09d7b3f2c2e8749150087aff2c434be4 soon after rootfs is
> mounted I'm getting the following lockdep trace (the machine in
> question is my tosa, booted from CF card with ide-cs driver).

I've no idea what a tosa is, but from the traces, I guess it's a VIVT
arm system?

> ------------[ cut here ]------------
> WARNING: at /home/lumag/tosa-tree/kernel/lockdep.c:2195 trace_hardirqs_on_caller+0xf0/0x170()
> Modules linked in:
> [<c0029fe4>] (dump_stack+0x0/0x14) from [<c003fc40>] (warn_on_slowpath+0x4c/0x84)
> [<c003fbf4>] (warn_on_slowpath+0x0/0x84) from [<c00629ac>] (trace_hardirqs_on_caller+0xf0/0x170)
>  r6:c0062a40 r5:00000001 r4:c381b080
> [<c00628bc>] (trace_hardirqs_on_caller+0x0/0x170) from [<c0062a40>] (trace_hardirqs_on+0x14/0x18)
>  r6:00000092 r5:00000000 r4:c3412b30
> [<c0062a2c>] (trace_hardirqs_on+0x0/0x18) from [<c03172b0>] (_spin_unlock_irq+0x30/0x60)
> [<c0317280>] (_spin_unlock_irq+0x0/0x60) from [<c002c3f4>] (__flush_dcache_aliases+0xec/0xf8)
>  r4:c3412b50
> [<c002c308>] (__flush_dcache_aliases+0x0/0xf8) from [<c002c474>] (flush_dcache_page+0x74/0x9c)
> [<c002c400>] (flush_dcache_page+0x0/0x9c) from [<c008f958>] (copy_to_high_bio_irq+0x64/0xb0)
>  r5:c386d668 r4:c3a2b000

OK, so this is the problem and it's coming from within arch/arm.  The
complaint is that we're still running at hardirq context but the
spin_unlock_irq would enable interrupts.

This is because of the definition in asm/cacheflush.h of
flush_dcache_mmap_unlock().

This looks to be a lockdep bug:  IDE interrupts don't have IRQF_DISABLED
set, so they're supposed to be running with interrupts enabled.
However, lockdep actually turns interrupts off anyway and complains
bitterly (in this case) if they get turned on for any reason.

A work around would be to run without lockdep, but I think we really
need lockdep fixing to work properly when IRQF_DISABLED isn't set.

James