* Nick Piggin [off-list ref] wrote:

quoted

[10138.175796]  [<c0105de3>] show_trace+0x12/0x14
[10138.180291]  [<c0105dfb>] dump_stack+0x16/0x18
[10138.184769]  [<c011609f>] native_smp_call_function_mask+0x138/0x13d
[10138.191117]  [<c0117606>] smp_call_function+0x1e/0x24
[10138.196210]  [<c012f85c>] on_each_cpu+0x25/0x50
[10138.200807]  [<c0115c74>] flush_tlb_all+0x1e/0x20
[10138.205553]  [<c016caaf>] kmap_high+0x1b6/0x417
[10138.210118]  [<c011ec88>] kmap+0x4d/0x4f
[10138.214102]  [<c026a9d8>] ntfs_end_buffer_async_read+0x228/0x2f9
[10138.220163]  [<c01a0e9e>] end_bio_bh_io_sync+0x26/0x3f
[10138.225352]  [<c01a2b09>] bio_endio+0x42/0x6d
[10138.229769]  [<c02c2a08>] __end_that_request_first+0x115/0x4ac
[10138.235682]  [<c02c2da7>] end_that_request_chunk+0x8/0xa
[10138.241052]  [<c0365943>] ide_end_request+0x55/0x10a
[10138.246058]  [<c036dae3>] ide_dma_intr+0x6f/0xac
[10138.250727]  [<c0366d83>] ide_intr+0x93/0x1e0
[10138.255125]  [<c015afb4>] handle_IRQ_event+0x5c/0xc9

Looks like ntfs is kmap()ing from interrupt context. Should be using 
kmap_atomic instead, I think.

it's not atomic interrupt context but irq thread context - and -rt 
remaps kmap_atomic() to kmap() internally.

the problem seems to be what Mike's patch works around: fiddling with 
irq flags in the ntfs code. That fiddling seems quite unnecessary at 
first sight.

	Ingo