Date: Sun, 23 Aug 2015 09:54:28 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: John-Mark Gurney <jmg@funkthat.com>, FreeBSD Current <freebsd-current@FreeBSD.org> Cc: Lawrence Stewart <lstewart@room52.net>, Pawel Pekala <pawel@FreeBSD.org>, "K. Macy" <kmacy@FreeBSD.org> Subject: Re: Instant panic while trying run ports-mgmt/poudriere Message-ID: <55D96E24.9060106@FreeBSD.org> In-Reply-To: <55CB5428.2090505@room52.net> References: <20150713231205.627bab36@FreeBSD.org> <20150714223829.GY8523@funkthat.com> <20150715174616.652d0aea@FreeBSD.org> <20150715180526.GM8523@funkthat.com> <20150715223703.78b9197c@FreeBSD.org> <CAHM0Q_PLRP4t6JgkstXHNOVV%2B2DyathOgi8bg4-RQkW-BcGXow@mail.gmail.com> <20150806233328.47a02594@FreeBSD.org> <55CB5428.2090505@room52.net>
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On 12/08/2015 17:11, Lawrence Stewart wrote:
> On 08/07/15 07:33, Pawel Pekala wrote:
>> Hi K.,
>>
>> On 2015-08-06 12:33 -0700, "K. Macy" <kmacy@freebsd.org> wrote:
>>> Is this still happening?
>>
>> Still crashes:
>
> +1 for me running r286617
Here is another +1 with r286922.
I can add a couple of bits of debugging data:
(kgdb) fr 8
#8 0xffffffff80639d60 in knote (list=0xfffff8019a733ea0,
hint=2147483648, lockflags=<value optimized out>) at
/usr/src/sys/kern/kern_event.c:1964
1964 } else if ((lockflags & KNF_NOKQLOCK) != 0) {
(kgdb) p *list
$2 = {kl_list = {slh_first = 0x0}, kl_lock = 0xffffffff8063a1e0
<knlist_mtx_lock>, kl_unlock = 0xffffffff8063a200 <knlist_mtx_unlock>,
kl_assert_locked = 0xffffffff8063a220 <knlist_mtx_assert_locked>,
kl_assert_unlocked = 0xffffffff8063a240 <knlist_mtx_assert_unlocked>,
kl_lockarg = 0xfffff8019a733bb0}
(kgdb) disassemble
Dump of assembler code for function knote:
0xffffffff80639d00 <knote+0>: push %rbp
0xffffffff80639d01 <knote+1>: mov %rsp,%rbp
0xffffffff80639d04 <knote+4>: push %r15
0xffffffff80639d06 <knote+6>: push %r14
0xffffffff80639d08 <knote+8>: push %r13
0xffffffff80639d0a <knote+10>: push %r12
0xffffffff80639d0c <knote+12>: push %rbx
0xffffffff80639d0d <knote+13>: sub $0x18,%rsp
0xffffffff80639d11 <knote+17>: mov %edx,%r12d
0xffffffff80639d14 <knote+20>: mov %rsi,-0x30(%rbp)
0xffffffff80639d18 <knote+24>: mov %rdi,%rbx
0xffffffff80639d1b <knote+27>: test %rbx,%rbx
0xffffffff80639d1e <knote+30>: je 0xffffffff80639ef6 <knote+502>
0xffffffff80639d24 <knote+36>: mov %r12d,%eax
0xffffffff80639d27 <knote+39>: and $0x1,%eax
0xffffffff80639d2a <knote+42>: mov %eax,-0x3c(%rbp)
0xffffffff80639d2d <knote+45>: mov 0x28(%rbx),%rdi
0xffffffff80639d31 <knote+49>: je 0xffffffff80639d38 <knote+56>
0xffffffff80639d33 <knote+51>: callq *0x18(%rbx)
0xffffffff80639d36 <knote+54>: jmp 0xffffffff80639d42 <knote+66>
0xffffffff80639d38 <knote+56>: callq *0x20(%rbx)
0xffffffff80639d3b <knote+59>: mov 0x28(%rbx),%rdi
0xffffffff80639d3f <knote+63>: callq *0x8(%rbx)
0xffffffff80639d42 <knote+66>: mov %rbx,-0x38(%rbp)
0xffffffff80639d46 <knote+70>: mov (%rbx),%rbx
0xffffffff80639d49 <knote+73>: test %rbx,%rbx
0xffffffff80639d4c <knote+76>: je 0xffffffff80639ee5 <knote+485>
0xffffffff80639d52 <knote+82>: and $0x2,%r12d
0xffffffff80639d56 <knote+86>: nopw %cs:0x0(%rax,%rax,1)
0xffffffff80639d60 <knote+96>: mov 0x28(%rbx),%r14
Panic is in the last quoted instruction.
And:
(kgdb) i reg
rax 0x246 582
rbx 0xdeadc0dedeadc0de -2401050962867404578
rcx 0x0 0
rdx 0x12e 302
rsi 0xffffffff80a26a5a -2136839590
rdi 0xffffffff80e81b80 -2132272256
rbp 0xfffffe02b7efea20 0xfffffe02b7efea20
rsp 0xfffffe02b7efe9e0 0xfffffe02b7efe9e0
r8 0xffffffff80a269ce -2136839730
r9 0xffffffff80e82838 -2132269000
r10 0x10000 65536
r11 0xffffffff80fabd10 -2131051248
r12 0x0 0
r13 0xfffff801ff84a818 -8787511171048
r14 0xfffff801ff84a800 -8787511171072
r15 0xfffff8019a6974f0 -8789207452432
rip 0xffffffff80639d60 0xffffffff80639d60 <knote+96>
eflags 0x10286 66182
I think that $rbx stands out here (this is a kernel with INVARIANTS).
Looking at the code, is it possible that one of the calls from within
the loop's body modifies the list? If that is so and provided that is a
valid behavior, then maybe using SLIST_FOREACH_SAFE would help.
--
Andriy Gapon
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