[asterisk-bugs] [DAHDI 0012657]: No room for chans on E1 span (insmod: page allocation failure. order:5)

[noreply at bugs.digium.com]

The following issue has been ASSIGNED. 
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http://bugs.digium.com/view.php?id=12657 
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Reported By:                tzafrir
Assigned To:                kpfleming
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Project:                    DAHDI
Issue ID:                   12657
Category:                   General
Reproducibility:            random
Severity:                   minor
Priority:                   normal
Status:                     assigned
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Date Submitted:             05-15-2008 07:52 CDT
Last Modified:              07-02-2008 08:24 CDT
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Summary:                    No room for chans on E1 span (insmod: page
allocation failure. order:5)
Description: 
An E1 span requires a span of at least 31 channels. All the channels of a
span are allocated in a single array. struct zt_chan takes around 2200
bytes. Thus an array of 31 of them takes around 68200 . This is more than
16 pages (4096kB), and hence the allocation requires a free block of 32
pages - order 5.

If the system is low enough on memory and/or fragmented enough, there will
not be such a block available.

In such a case we get a scary-looking oops-like message, though in
practice we simply have a failed memory allocation that seems to be handled
gracefully by the driver.

How do we get rid of this big block of more than 64kB of memory? Maybe if
we manage to cut some 100 bytes or so from that struct ithat allocation
will become an order 4 (16 pages) one and thus a bit less of a problem.

May 15 08:37:53 brodni kernel: TE2XXP version c01a016a, burst ON
May 15 08:37:53 brodni kernel: insmod: page allocation failure. order:5,
mode:0xd0
May 15 08:37:53 brodni kernel:  [<c04540ed>] __alloc_pages+0x26a/0x27e
May 15 08:37:53 brodni kernel:  [<c0467138>]
cache_alloc_refill+0x26d/0x44f
May 15 08:37:53 brodni kernel:  [<c0466ec1>] kmem_cache_alloc+0x41/0x4b
May 15 08:37:53 brodni kernel:  [<cfbf6f1d>] t4_init_one+0x533/0xea8
[wct4xxp]
May 15 08:37:53 brodni kernel:  [<c05439eb>] __driver_attach+0x0/0x6b
May 15 08:37:53 brodni kernel:  [<c04e6bf4>] pci_device_probe+0x36/0x57
May 15 08:37:53 brodni kernel:  [<c0543945>]
driver_probe_device+0x42/0x8b
May 15 08:37:53 brodni kernel:  [<c0543a2f>] __driver_attach+0x44/0x6b
May 15 08:37:53 brodni kernel:  [<c054344a>] bus_for_each_dev+0x37/0x59
May 15 08:37:53 brodni kernel:  [<c05438af>] driver_attach+0x11/0x13
May 15 08:37:53 brodni kernel:  [<c05439eb>] __driver_attach+0x0/0x6b
May 15 08:37:53 brodni kernel:  [<c0543152>] bus_add_driver+0x64/0xfd
May 15 08:37:53 brodni kernel:  [<c04e6d22>]
__pci_register_driver+0x47/0x63
May 15 08:37:53 brodni kernel:  [<cf83300f>] t4_init+0xf/0x1a [wct4xxp]
May 15 08:37:53 brodni kernel:  [<c043d0d4>]
sys_init_module+0x16e7/0x186a
May 15 08:37:53 brodni kernel:  [<c046a5df>] do_sync_read+0xb6/0xf1
May 15 08:37:53 brodni kernel:  [<c0403eff>] syscall_call+0x7/0xb
May 15 08:37:53 brodni kernel:  =======================
May 15 08:37:53 brodni kernel: Mem-info:
May 15 08:37:53 brodni kernel: DMA per-cpu:
May 15 08:37:53 brodni kernel: cpu 0 hot: high 0, batch 1 used:0
May 15 08:37:53 brodni kernel: cpu 0 cold: high 0, batch 1 used:0
May 15 08:37:53 brodni kernel: DMA32 per-cpu: empty
May 15 08:37:53 brodni kernel: Normal per-cpu:
May 15 08:37:53 brodni kernel: cpu 0 hot: high 90, batch 15 used:77
May 15 08:37:53 brodni kernel: cpu 0 cold: high 30, batch 7 used:27
May 15 08:37:53 brodni kernel: HighMem per-cpu: empty
May 15 08:37:53 brodni kernel: Free pages:       79676kB (0kB HighMem)
May 15 08:37:53 brodni kernel: Active:27735 inactive:3608 dirty:81
writeback:0 unstable:0 free:19919 slab:6728 mapped:4772 pagetables:716
May 15 08:37:53 brodni kernel: DMA free:8020kB min:132kB low:164kB
high:196kB active:140kB inactive:0kB present:16384kB pages_scanned:0
all_unreclaimable? no
May 15 08:37:53 brodni kernel: lowmem_reserve[]: 0 0 223 223
May 15 08:37:53 brodni kernel: DMA32 free:0kB min:0kB low:0kB high:0kB
active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no
May 15 08:37:54 brodni kernel: lowmem_reserve[]: 0 0 223 223
May 15 08:37:54 brodni kernel: Normal free:71656kB min:1844kB low:2304kB
high:27
64kB active:110800kB inactive:14432kB present:229312kB pages_scanned:153
all_unreclaimable? no
May 15 08:37:54 brodni kernel: lowmem_reserve[]: 0 0 0 0
May 15 08:37:54 brodni kernel: HighMem free:0kB min:128kB low:128kB
high:128kB active:0kB inactive:0kB present:0kB pages_scanned:0
all_unreclaimable? no
May 15 08:37:54 brodni kernel: lowmem_reserve[]: 0 0 0 0
May 15 08:37:54 brodni kernel: DMA: 177*4kB 156*8kB 119*16kB 64*32kB
31*64kB 1*1
28kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 8020kB
May 15 08:37:54 brodni kernel: DMA32: empty
May 15 08:37:54 brodni kernel: Normal: 194*4kB 4050*8kB 1689*16kB 304*32kB
25*64
kB 1*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 71656kB
May 15 08:37:54 brodni kernel: Swap cache: add 1028, delete 1028, find
805/878, race 0+0

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Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
07-02-08 08:24  svnbot         Status                   new => assigned     
07-02-08 08:24  svnbot         Assigned To               => kpfleming       
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