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SubjectRe: 2.6.25-$sha1: RIP call_for_each_cic+0x25/0x50
On Mon, Apr 28, 2008 at 02:04:13PM +0200, Jens Axboe wrote:
> On Mon, Apr 28 2008, Andrew Morton wrote:
> > On Mon, 28 Apr 2008 02:55:53 +0400 Alexey Dobriyan <adobriyan@gmail.com> wrote:
> >
> > > This happened while ~90 cross-compile jobs were running in parallel on
> > > ext2/noatime partition (slowly -- much debugging was on)
> > >
> > >
> > > general protection fault: 0000 [1] PREEMPT SMP DEBUG_PAGEALLOC
> > > CPU 0
> > > Modules linked in: ext2 nf_conntrack_irc ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 xt_state nf_conntrack iptable_filter ip_tables x_tables usblp uhci_hcd ehci_hcd usbcore sr_mod cdrom
> > > Pid: 16483, comm: as Not tainted 2.6.25-c3bf9bc243092c53946fd6d8ebd6dc2f4e572d48 #1
> > > RIP: 0010:[<ffffffff80307525>] [<ffffffff80307525>] call_for_each_cic+0x25/0x50
> > > RSP: 0018:ffff810170811e58 EFLAGS: 00010202
> > > RAX: 6b6b6b6b6b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: 0000000000000000
> > > RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff81010ff92000
> > > RBP: ffff810170811e78 R08: 0000000000000001 R09: 0000000000000000
> > > R10: 0000000000000000 R11: ffff8100010069d8 R12: ffff810138ada300
> > > R13: ffffffff803075b0 R14: ffff81017fcd2000 R15: ffff81010ff92168
> > > FS: 00002ac3462426f0(0000) GS:ffffffff805d0000(0000) knlGS:0000000000000000
> > > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> > > CR2: 00002ab602550000 CR3: 000000013609d000 CR4: 0000000000000660
> > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> > > Process as (pid: 16483, threadinfo ffff810170810000, task ffff81010ff92000)
> > > Stack: ffff810170811e88 ffff810138ada300 0000000000000010 ffff81010ff92100
> > > ffff810170811e88 ffffffff80307580 ffff810170811ea8 ffffffff80302a55
> > > ffff81010ff92100 ffff810138ada300 ffff810170811ec8 ffffffff80302b1f
> > > Call Trace:
> > > [<ffffffff80307580>] cfq_free_io_context+0x10/0x20
> > > [<ffffffff80302a55>] put_io_context+0x85/0x90
> > > [<ffffffff80302b1f>] exit_io_context+0x8f/0xb0
> > > [<ffffffff80235d19>] do_exit+0x549/0x780
> > > [<ffffffff80235f8e>] do_group_exit+0x3e/0xb0
> > > [<ffffffff80236012>] sys_exit_group+0x12/0x20
> > > [<ffffffff8020b6db>] system_call_after_swapgs+0x7b/0x80
> > >
> > >
> > > Code: 84 00 00 00 00 00 55 48 89 e5 41 55 49 89 f5 41 54 49 89 fc 53 48 83 ec 08 e8 18 e1 f5 ff 49 8b 44 24 68 48 85 c0 74 1e 48 89 c3 <48> 8b 03 48 8d 73 88 4c 89 e7 0f 18 08 41 ff d5 48 8b 03 48 85
> > > RIP [<ffffffff80307525>] call_for_each_cic+0x25/0x50
> > > RSP <ffff810170811e58>
> > > ---[ end trace ca143223eefdc828 ]---
> > > Fixing recursive fault but reboot is needed!
> > >
> > >
> > > ffffffff80307500 <call_for_each_cic>:
> > > ffffffff80307500: 55 push %rbp
> > > ffffffff80307501: 48 89 e5 mov %rsp,%rbp
> > > ffffffff80307504: 41 55 push %r13
> > > ffffffff80307506: 49 89 f5 mov %rsi,%r13
> > > ffffffff80307509: 41 54 push %r12
> > > ffffffff8030750b: 49 89 fc mov %rdi,%r12
> > > ffffffff8030750e: 53 push %rbx
> > > ffffffff8030750f: 48 83 ec 08 sub $0x8,%rsp
> > > ffffffff80307513: e8 18 e1 f5 ff callq ffffffff80265630 <__rcu_read_lock>
> > > ffffffff80307518: 49 8b 44 24 68 mov 0x68(%r12),%rax
> > > ffffffff8030751d: 48 85 c0 test %rax,%rax
> > > ffffffff80307520: 74 1e je ffffffff80307540 <call_for_each_cic+0x40>
> > > ffffffff80307522: 48 89 c3 mov %rax,%rbx
> > > ffffffff80307525: 48 8b 03 mov (%rbx),%rax
> >
> > use-after-free.
>
> Yep, apparently a freed entry on the list. Not good...
>
> > > ffffffff80307528: 48 8d 73 88 lea -0x78(%rbx),%rsi
> > > ffffffff8030752c: 4c 89 e7 mov %r12,%rdi
> > > ffffffff8030752f: 0f 18 08 prefetcht0 (%rax)
> > > ffffffff80307532: 41 ff d5 callq *%r13
> > > ffffffff80307535: 48 8b 03 mov (%rbx),%rax
> > > ffffffff80307538: 48 85 c0 test %rax,%rax
> > > ffffffff8030753b: 48 89 c3 mov %rax,%rbx
> > > ffffffff8030753e: 75 e5 jne ffffffff80307525 <call_for_each_cic+0x25>
> > > ffffffff80307540: e8 2b e0 f5 ff callq ffffffff80265570 <__rcu_read_unlock>
> > > ffffffff80307545: 48 83 c4 08 add $0x8,%rsp
> > > ffffffff80307549: 5b pop %rbx
> > > ffffffff8030754a: 41 5c pop %r12
> > > ffffffff8030754c: 41 5d pop %r13
> > > ffffffff8030754e: c9 leaveq
> > > ffffffff8030754f: c3 retq
> >
> > cfq-iosched.c hasn't been altered (yet) so it might not be a regression.
>
> It's not a regression, it's definitely in 2.6.25 as well. So that's a
> bit scary, I've been looking over this stuff this morning but haven't
> pin pointed anything yet.
>
> Alexey, is this something that reproduces for you?

Not yet, second run of same workload went fine and I've never seen such
oopses before.

FWIW, the only unusual thing in .config is preemptible RCU. Before
2.6.25 it was turned off here.



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