[lttng-dev] [PATCH lttng-modules] Fix: Building the event list fails on fragmented memory

[Mathieu Desnoyers]

----- On Jun 23, 2015, at 9:46 AM, Jan Glauber jan.glauber at gmail.com wrote:

> On Sat, Jun 13, 2015 at 07:32:28PM +0000, Mathieu Desnoyers wrote:
>> ----- On Jun 10, 2015, at 9:17 AM, Martin Leisener martin at leisener.de wrote:
>> 
>> > Hi Mathieu,
>> > 
>> > sorry for sending the broken patch, I fell for some "smart" formating of my
>> > email client, I cannot utilize it myself the way I send it.
>> > Hence I now send the patch again as it was original intended. Sent to myself, I
>> > can apply it, so I hope it now works in general as well
>> > I examined as recommended diff -urN, it seems the output can be utilized by
>> > patch the same way as git diff.
>> > Hope it is now received the way I intended.
>> 
>> Hi Martin,
>> 
>> I tried you patch on a x86-64 machine (my laptop), and although taking a
>> single kernel trace worked fine, it appears to OOPS when I run
>> 
>> (in lttng-tools)
>> cd tests
>> ./run.sh root_regression
> 
> Hi Mathieu,
> 
> can you please share the oops message so I can have a look?

Sure,

Here is the backtrace happening with the attached patch over lttng-modules
commit 8c6e7f13c778701dec2d6549f1e2ca98970907a0. I modified your patch
slightly.

[ 4078.314978] BUG: unable to handle kernel paging request at ffffc900038d995e
[ 4078.315824] IP: [<ffffffff81316f12>] __memcpy+0x12/0x20
[ 4078.315824] PGD 236c92067 PUD 236c93067 PMD bac0c067 PTE 0
[ 4078.315824] Oops: 0000 [#1] SMP 
[ 4078.315824] Modules linked in: lttng_probe_workqueue(O) lttng_probe_vmscan(O) lttng_probe_udp(O) lttng_probe_timer(O) lttng_probe_sunrpc(O) lttng_probe_statedump(O) lttng_probe_sock(O) lttng_probe_skb(O) lttng_probe_signal(O) lttng_probe_scsi(O) lttng_probe_sched(O) lttng_probe_regmap(O) lttng_probe_rcu(O) lttng_probe_random(O) lttng_probe_printk(O) lttng_probe_power(O) lttng_probe_net(O) lttng_probe_napi(O) lttng_probe_module(O) lttng_probe_kmem(O) lttng_probe_jbd2(O) lttng_probe_irq(O) lttng_probe_ext4(O) lttng_probe_compaction(O) lttng_probe_block(O) lttng_types(O) lttng_ring_buffer_metadata_mmap_client(O) lttng_ring_buffer_client_mmap_overwrite(O) lttng_ring_buffer_client_mmap_discard(O) lttng_ring_buffer_metadata_client(O) lttng_ring_buffer_client_overwrite(O) lttng_ring_buffer_client_discard(O) lttng_tracer(O) lttng_statedump(O) lttng_kprobes(O) lttng_lib_ring_buffer(O) lttng_kretprobes(O) virtio_blk virtio_net virtio_pci virtio_ring virtio
[ 4078.315824] CPU: 5 PID: 4258 Comm: lttng-consumerd Tainted: G           O    4.1.0 #7
[ 4078.315824] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[ 4078.315824] task: ffff8802350c3660 ti: ffff8800bae84000 task.ti: ffff8800bae84000
[ 4078.315824] RIP: 0010:[<ffffffff81316f12>]  [<ffffffff81316f12>] __memcpy+0x12/0x20
[ 4078.315824] RSP: 0018:ffff8800bae87da0  EFLAGS: 00010246
[ 4078.315824] RAX: ffff880235439025 RBX: 0000000000000fd8 RCX: 00000000000001fb
[ 4078.315824] RDX: 0000000000000000 RSI: ffffc900038d995e RDI: ffff880235439025
[ 4078.315824] RBP: ffff8800bae87db8 R08: ffff8800bacecc00 R09: 0000000000008000
[ 4078.315824] R10: 0000000000000000 R11: 0000000000000246 R12: ffff8800bae87dc8
[ 4078.315824] R13: ffff88023466e800 R14: 0000000000000fd8 R15: 0000000000000fd8
[ 4078.315824] FS:  00007f5d3b1cc700(0000) GS:ffff8802372a0000(0000) knlGS:0000000000000000
[ 4078.315824] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 4078.315824] CR2: ffffc900038d995e CR3: 00000000bb1ed000 CR4: 00000000000006e0
[ 4078.315824] Stack:
[ 4078.315824]  ffffffffa01ac797 ffff8800bb5bd480 ffff8800bb5bd4d0 ffff8800bae87e48
[ 4078.315824]  ffffffffa0073060 ffff88023466e800 0000000000000000 0000000000000fd8
[ 4078.315824]  ffffffff00000001 ffff8800bacecc00 0000000000000fd8 0000000000008025
[ 4078.315824] Call Trace:
[ 4078.315824]  [<ffffffffa01ac797>] ? lttng_event_write+0x87/0xb0 [lttng_ring_buffer_metadata_client]
[ 4078.315824]  [<ffffffffa0073060>] lttng_metadata_output_channel+0xd0/0x120 [lttng_tracer]
[ 4078.315824]  [<ffffffffa00755f9>] lttng_metadata_ring_buffer_ioctl+0x79/0xd0 [lttng_tracer]
[ 4078.315824]  [<ffffffff8117ba10>] do_vfs_ioctl+0x2e0/0x4e0
[ 4078.315824]  [<ffffffff812b35c7>] ? file_has_perm+0x87/0xa0
[ 4078.315824]  [<ffffffff8117bc91>] SyS_ioctl+0x81/0xa0
[ 4078.315824]  [<ffffffff810115d1>] ? syscall_trace_leave+0xd1/0xe0
[ 4078.315824]  [<ffffffff818bbd37>] tracesys_phase2+0x84/0x89
[ 4078.315824] Code: 5b 5d c3 66 0f 1f 44 00 00 e8 6b fc ff ff eb e1 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 <f3> 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 f3 
[ 4078.315824] RIP  [<ffffffff81316f12>] __memcpy+0x12/0x20
[ 4078.315824]  RSP <ffff8800bae87da0>
[ 4078.315824] CR2: ffffc900038d995e
[ 4078.315824] ---[ end trace a05b652829ceda48 ]---
[ 4078.433848] LTTng: block device enumeration is not supported by kernel


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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