Possible regression with skb_clone() in 2.6.36

From: Gustavo F. Padovan
Date: Mon Aug 30 2010 - 19:10:55 EST

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I've been experiencing some problems when running the L2CAP Streaming mode in
2.6.36. The system quickly runs in an Out Of Memory condition and crash. That
wasn't happening before, so I think we may have a regression here (I didn't find
where yet). The crash log is below.

The following patch does not fix the regression, but shows that removing the
skb_clone() call from l2cap_streaming_send() makes the problem goes away. The
patch is good anyway since it saves memory and time when sending Streaming mode
packets.

[ 5066.137533] Bluetooth: L2CAP ver 2.15
[ 5066.137873] Bluetooth: L2CAP socket layer initialized
[ 5066.545179] Bluetooth: RFCOMM TTY layer initialized
[ 5066.545879] Bluetooth: RFCOMM socket layer initialized
[ 5066.546582] Bluetooth: RFCOMM ver 1.11
[ 5092.268021] l2test invoked oom-killer: gfp_mask=0x4d0, order=0, oom_adj=0, oom_score_adj=0
[ 5092.268872] Pid: 3897, comm: l2test Not tainted 2.6.36-rc3 #5
[ 5092.269863] Call Trace:
[ 5092.270265] [<ffffffff8138b6a6>] ? _raw_spin_unlock+0x26/0x30
[ 5092.270878] [<ffffffff810c0827>] T.427+0x77/0x1e0
[ 5092.271874] [<ffffffff811b85e7>] ? security_real_capable_noaudit+0x37/0x60
[ 5092.272956] [<ffffffff810c0e3a>] out_of_memory+0x2ca/0x2f0
[ 5092.273894] [<ffffffff810c3d43>] __alloc_pages_nodemask+0x693/0x6b0
[ 5092.274871] [<ffffffff810ea3e6>] cache_alloc_refill+0x2d6/0x5c0
[ 5092.275864] [<ffffffff810ea805>] __kmalloc+0x135/0x150
[ 5092.276876] [<ffffffff8130f2ae>] __alloc_skb+0x6e/0x150
[ 5092.277865] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.278652] [<ffffffff8130ace2>] sock_alloc_send_pskb+0x1c2/0x320
[ 5092.278927] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.279864] [<ffffffff81312add>] ? memcpy_fromiovec+0x6d/0x90
[ 5092.280864] [<ffffffff8130ae50>] sock_alloc_send_skb+0x10/0x20
[ 5092.281867] [<ffffffffa00e600f>] l2cap_create_iframe_pdu+0x9f/0x2c0 [l2cap]
[ 5092.282865] [<ffffffffa00e84b9>] l2cap_sock_sendmsg+0x5d9/0x910 [l2cap]
[ 5092.283932] [<ffffffff8138ba3c>] ? restore_args+0x0/0x30
[ 5092.284865] [<ffffffff8130725b>] sock_sendmsg+0xdb/0x100
[ 5092.285652] [<ffffffff8138ba3c>] ? restore_args+0x0/0x30
[ 5092.285864] [<ffffffff8138ba3c>] ? restore_args+0x0/0x30
[ 5092.286864] [<ffffffff813073c0>] sys_sendto+0xf0/0x130
[ 5092.287864] [<ffffffff8138b60b>] ? _raw_spin_unlock_irq+0x2b/0x40
[ 5092.288872] [<ffffffff81093cfd>] ? trace_hardirqs_on_caller+0x13d/0x180
[ 5092.289927] [<ffffffff81093d4d>] ? trace_hardirqs_on+0xd/0x10
[ 5092.290864] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.291649] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.291864] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.292864] [<ffffffff8130740f>] sys_send+0xf/0x20
[ 5092.293870] [<ffffffff8132ccd6>] compat_sys_socketcall+0x146/0x1f0
[ 5092.294875] [<ffffffff81053ee4>] sysenter_dispatch+0x7/0x30
[ 5092.295673] Mem-Info:
[ 5092.295863] DMA per-cpu:
[ 5092.296214] CPU 0: hi: 0, btch: 1 usd: 0
[ 5092.296925] DMA32 per-cpu:
[ 5092.297298] CPU 0: hi: 90, btch: 15 usd: 85
[ 5092.297864] active_anon:504 inactive_anon:543 isolated_anon:0
[ 5092.297865] active_file:14 inactive_file:3 isolated_file:0
[ 5092.297866] unevictable:0 dirty:0 writeback:3 unstable:0
[ 5092.297866] free:728 slab_reclaimable:559 slab_unreclaimable:39895
[ 5092.297867] mapped:12 shmem:35 pagetables:84 bounce:0
[ 5092.299944] DMA free:1064kB min:124kB low:152kB high:184kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15768kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:14916kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
[ 5092.301862] lowmem_reserve[]: 0 236 236 236
[ 5092.303134] DMA32 free:1848kB min:1904kB low:2380kB high:2856kB active_anon:2016kB inactive_anon:2172kB active_file:56kB inactive_file:12kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:242380kB mlocked:0kB dirty:0kB writeback:12kB mapped:48kB shmem:140kB slab_reclaimable:2236kB slab_unreclaimable:144664kB kernel_stack:456kB pagetables:336kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:103 all_unreclaimable? yes
[ 5092.304962] lowmem_reserve[]: 0 0 0 0
[ 5092.306066] DMA: 0*4kB 1*8kB 0*16kB 1*32kB 0*64kB 0*128kB 0*256kB 0*512kB 1*1024kB 0*2048kB 0*4096kB = 1064kB
[ 5092.307862] DMA32: 10*4kB 2*8kB 0*16kB 0*32kB 0*64kB 0*128kB 1*256kB 1*512kB 1*1024kB 0*2048kB 0*4096kB = 1848kB
[ 5092.309467] 52 total pagecache pages
[ 5092.309862] 0 pages in swap cache
[ 5092.310317] Swap cache stats: add 0, delete 0, find 0/0
[ 5092.310862] Free swap = 0kB
[ 5092.311260] Total swap = 0kB
[ 5092.313796] 65530 pages RAM
[ 5092.313868] 22603 pages reserved
[ 5092.314324] 206 pages shared
[ 5092.314862] 39353 pages non-shared
[ 5092.315348] [ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name
[ 5092.315867] [ 1] 0 1 438 19 0 0 0 init
[ 5092.316871] [ 1018] 0 1018 537 75 0 -17 -1000 udevd
[ 5092.318867] [ 2217] 101 2217 606 39 0 0 0 dbus-daemon
[ 5092.319865] [ 2825] 0 2825 481 29 0 0 0 dhcpcd
[ 5092.320865] [ 3497] 0 3497 1091 83 0 0 0 sshd
[ 5092.321969] [ 3535] 0 3535 477 31 0 0 0 agetty
[ 5092.322864] [ 3536] 0 3536 477 30 0 0 0 agetty
[ 5092.323864] [ 3537] 0 3537 477 29 0 0 0 agetty
[ 5092.325937] [ 3538] 0 3538 477 31 0 0 0 agetty
[ 5092.326865] [ 3539] 0 3539 477 31 0 0 0 agetty
[ 5092.327864] [ 3540] 0 3540 477 31 0 0 0 agetty
[ 5092.328864] [ 3541] 0 3541 1738 105 0 0 0 sshd
[ 5092.329865] [ 3545] 0 3545 745 72 0 0 0 bash
[ 5092.330864] [ 3550] 0 3550 706 43 0 0 0 screen
[ 5092.331866] [ 3551] 0 3551 772 124 0 0 0 screen
[ 5092.332965] [ 3552] 0 3552 745 77 0 0 0 bash
[ 5092.333865] [ 3557] 0 3557 745 77 0 0 0 bash
[ 5092.334867] [ 3562] 0 3562 536 75 0 -17 -1000 udevd
[ 5092.336865] [ 3567] 0 3567 536 75 0 -17 -1000 udevd
[ 5092.337865] [ 3887] 0 3887 935 54 0 0 0 bluetoothd
[ 5092.338864] [ 3896] 0 3896 458 24 0 0 0 l2test
[ 5092.339864] [ 3897] 0 3897 458 24 0 0 0 l2test
[ 5092.340933] [ 3942] 0 3942 458 29 0 0 0 l2test
[ 5092.341863] Kernel panic - not syncing: Out of memory and no killable processes...
[ 5092.341864]
[ 5092.342864] Pid: 3897, comm: l2test Not tainted 2.6.36-rc3 #5
[ 5092.343862] Call Trace:
[ 5092.344934] [<ffffffff813884d9>] panic+0x8c/0x199
[ 5092.345621] [<ffffffff810c0e54>] out_of_memory+0x2e4/0x2f0
[ 5092.345864] [<ffffffff810c3d43>] __alloc_pages_nodemask+0x693/0x6b0
[ 5092.346894] [<ffffffff810ea3e6>] cache_alloc_refill+0x2d6/0x5c0
[ 5092.347864] [<ffffffff810ea805>] __kmalloc+0x135/0x150
[ 5092.348871] [<ffffffff8130f2ae>] __alloc_skb+0x6e/0x150
[ 5092.349865] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.350628] [<ffffffff8130ace2>] sock_alloc_send_pskb+0x1c2/0x320
[ 5092.350935] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.351864] [<ffffffff81312add>] ? memcpy_fromiovec+0x6d/0x90
[ 5092.352864] [<ffffffff8130ae50>] sock_alloc_send_skb+0x10/0x20
[ 5092.353867] [<ffffffffa00e600f>] l2cap_create_iframe_pdu+0x9f/0x2c0 [l2cap]
[ 5092.354865] [<ffffffffa00e84b9>] l2cap_sock_sendmsg+0x5d9/0x910 [l2cap]
[ 5092.355864] [<ffffffff8138ba3c>] ? restore_args+0x0/0x30
[ 5092.356864] [<ffffffff8130725b>] sock_sendmsg+0xdb/0x100
[ 5092.357612] [<ffffffff8138ba3c>] ? restore_args+0x0/0x30
[ 5092.357931] [<ffffffff8138ba3c>] ? restore_args+0x0/0x30
[ 5092.358864] [<ffffffff813073c0>] sys_sendto+0xf0/0x130
[ 5092.359864] [<ffffffff8138b60b>] ? _raw_spin_unlock_irq+0x2b/0x40
[ 5092.360929] [<ffffffff81093cfd>] ? trace_hardirqs_on_caller+0x13d/0x180
[ 5092.361866] [<ffffffff81093d4d>] ? trace_hardirqs_on+0xd/0x10
[ 5092.362864] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.363653] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.364868] [<ffffffff810d3a00>] ? might_fault+0x40/0x90
[ 5092.365865] [<ffffffff8130740f>] sys_send+0xf/0x20
[ 5092.366945] [<ffffffff8132ccd6>] compat_sys_socketcall+0x146/0x1f0
[ 5092.367865] [<ffffffff81053ee4>] sysenter_dispatch+0x7/0x30

-------
Gustavo F. Padovan (1):
Bluetooth: Simplify L2CAP Streaming mode sending

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Next message: Neil Brown: "Re: [PATCH 0/5] hybrid union filesystem prototype"
Previous message: Gustavo F. Padovan: "[PATCH] Bluetooth: Simplify L2CAP Streaming mode sending"
Next in thread: Gustavo F. Padovan: "[PATCH] Bluetooth: Simplify L2CAP Streaming mode sending"
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