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SubjectRe: Oops when trying to create more than 16000 timers
On Mon, Dec 15, 2008 at 11:37:38PM +0200, Pekka Enberg wrote:
> Hi Ottavio,
>
> On Mon, Dec 15, 2008 at 11:41 PM, Ottavio Campana
> <ottavio.campana@dei.unipd.it> wrote:
> >>> I am currently developing a software that needs approx 60k timers. I
> >>> currently use timer_create and all the relative functions to manage timers.
> >>>
> >>> I've noticed that after having created 16039 timers I always get an oops
> >>> from the kernel, which are always of the same kind:
> >>>
> >>> Dec 15 15:20:00 evolution kernel: [601680.417064] BUG: unable to handle
> >>> kernel NULL pointer dereference at 0000000000000040 .
> >>
> >> This would be a kernel bug so can you please post the full oops. See
> >> REPORTING-BUGS and Documentation/oops-tracing.txt for details.
> >
> > I hope the report is correct, please tell me if you want me to do
> > something else.
> >
> > RIP: 0010:[<ffffffff80245291>] [<ffffffff80245291>]
> > sys_timer_create+0x79/0x360
> > RSP: 0018:ffff81007a5ddef8 EFLAGS: 00010286
> > RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000086
> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000286
> > RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000001
> > R10: 00007f927adb3a50 R11: 0000000000000000 R12: 00000000016ed768
> > R13: 00000000016ed6d0 R14: 00007fff833dead0 R15: 00000000016ed754
> > FS: 00007f927b3cd6e0(0000) GS:ffff81007d37a9c0(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> > CR2: 0000000000000040 CR3: 000000007b00c000 CR4: 00000000000006e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> > Process timer_tester (pid: 2743, threadinfo ffff81007a5dc000, task
> > ffff81007a7936b0)
> > Stack: ffff81007646f9f8 0000000000000000 0000000000000000 ffffffff8029b4ed
> > 0000000000000000 ffff81007b024c80 0000000000000017 fffffffffffffff7
> > 00007f927b3da000 ffffffff8029ba36 0000000000000292 0000000000000000
> > Call Trace:
> > [<ffffffff8029b4ed>] vfs_write+0x121/0x156
> > [<ffffffff8029ba36>] sys_write+0x60/0x6e
> > [<ffffffff8020beca>] system_call_after_swapgs+0x8a/0x8f
> >
> >
> > Code: c6 0e 05 00 48 85 c0 74 3b 48 89 c5 e8 d0 a0 ff ff 48 85 c0 48 89
> > 45 40 75 11 48 8b 3d e1 22 3e 00 48 89 ee 31 ed e8 fe 10 05 00 <48> 8b
> > 7d 40 31 f6 ba 80 00 00 00 48 83 c7 18 e8 6b ae 0d 00 48
> > RIP [<ffffffff80245291>] sys_timer_create+0x79/0x360
> > RSP <ffff81007a5ddef8>
> > CR2: 0000000000000040
> > ---[ end trace 2e93d77cdbbd83c6 ]---
> >
> > Using decodecode
> >
> > Code: c6 0e 05 00 48 85 c0 74 3b 48 89 c5 e8 d0 a0 ff ff 48 85 c0 48 89
> > 45 40 75 11 48 8b 3d e1 22 3e 00 48 89 ee 31 ed e8 fe 10 05 00 <48> 8b
> > 7d 40 31 f6 ba 80 00 00 00 48 83 c7 18 e8 6b ae 0d 00 48
> >
> > /tmp/tmp.CcCjFxHOMN.o: file format elf64-x86-64
> >
> > Disassembly of section .text:
> >
> > 0000000000000000 <.text>:
> > 0: c6 (bad)
> > 1: 0e (bad)
> > 2: 05 00 48 85 c0 add $0xc0854800,%eax
> > 7: 74 3b je 0x44
> > 9: 48 89 c5 mov %rax,%rbp
> > c: e8 d0 a0 ff ff callq 0xffffffffffffa0e1
> > 11: 48 85 c0 test %rax,%rax
> > 14: 48 89 45 40 mov %rax,0x40(%rbp)
> > 18: 75 11 jne 0x2b
> > 1a: 48 8b 3d e1 22 3e 00 mov 0x3e22e1(%rip),%rdi # 0x3e2302
> > 21: 48 89 ee mov %rbp,%rsi
> > 24: 31 ed xor %ebp,%ebp
> > 26: e8 fe 10 05 00 callq 0x51129
> >
> > /tmp/tmp.CcCjFxHOMN.o: file format elf64-x86-64
> >
> > Disassembly of section .text:
> >
> > 0000000000000000 <.text>:
> > 0: 48 8b 7d 40 mov 0x40(%rbp),%rdi
> > 4: 31 f6 xor %esi,%esi
> > 6: ba 80 00 00 00 mov $0x80,%edx
> > b: 48 83 c7 18 add $0x18,%rdi
> > f: e8 6b ae 0d 00 callq 0xdae7f
> > 14: 48 rex.W
>
> I think you're simply hitting RLIMIT_SIGPENDING and then tripping over
> a bug in alloc_posix_timer() that's fixed by commit
> aa94fbd5ccd840c8ab26d02439ec799b03a72547 ("fix error-path NULL deref
> in alloc_posix_timer()") in 2.6.28-rc8.
>
> Dan, can you please send your patch to the -stable queue as well?
>

This patch is already in the 2.6.27 release.

thanks,

greg k-h


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