From: Sasha Levin <levinsasha928@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>
Cc: Dave Jones <davej@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: lockdep: Warning & NULL ptr deref
Date: Tue, 28 Feb 2012 10:24:52 -0500 [thread overview]
Message-ID: <1330442692.3719.7.camel@lappy> (raw)
Hi all,
I was debugging an issue with Trinity leaving multiple zombie processes while running, so after letting trinity run for a bit to create a nice bunch of them, I wanted to get a sysrq-t trace.
After running 'echo t > /proc/sysrq-trigger' I got the usual backtrace spew along with some scheduler debug info after that, but when lockdep tried printing lock data I got this:
[ 359.241034] Showing all locks held in the system:
[ 359.241034] 1 lock held by ksoftirqd/0/3:
[ 359.241034] #0:
[ 359.241034] ------------[ cut here ]------------
[ 359.241034] WARNING: at kernel/lockdep.c:146 print_lock+0xa0/0xb0()
[ 359.241034] Pid: 2852, comm: sh Not tainted 3.3.0-rc5-next-20120227-sasha-dirty #26
[ 359.241034] Call Trace:
[ 359.241034] [<ffffffff8110e1a0>] ? print_lock+0xa0/0xb0
[ 359.241034] [<ffffffff810ac705>] warn_slowpath_common+0x75/0xb0
[ 359.241034] [<ffffffff810ac805>] warn_slowpath_null+0x15/0x20
[ 359.241034] [<ffffffff8110e1a0>] print_lock+0xa0/0xb0
[ 359.241034] [<ffffffff8110e22e>] lockdep_print_held_locks+0x7e/0xf0
[ 359.241034] [<ffffffff81115220>] debug_show_all_locks+0x190/0x260
[ 359.241034] [<ffffffff810e47f7>] show_state_filter+0x177/0x220
[ 359.241034] [<ffffffff810e4680>] ? sched_show_task+0x190/0x190
[ 359.241034] [<ffffffff81971d4b>] sysrq_handle_showstate+0xb/0x10
[ 359.241034] [<ffffffff81972209>] __handle_sysrq+0x129/0x190
[ 359.241034] [<ffffffff81972270>] ? __handle_sysrq+0x190/0x190
[ 359.241034] [<ffffffff819722ba>] write_sysrq_trigger+0x4a/0x50
[ 359.241034] [<ffffffff81243c10>] proc_reg_write+0x80/0xc0
[ 359.241034] [<ffffffff811dba86>] vfs_write+0xc6/0x180
[ 359.241034] [<ffffffff811dbc2f>] sys_write+0x4f/0xa0
[ 359.241034] [<ffffffff826e4979>] system_call_fastpath+0x16/0x1b
[ 359.241034] ---[ end trace 80d8165bc39af078 ]---
[ 359.241034] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
[ 359.241034] IP: [<ffffffff8110e03d>] get_usage_chars+0xd/0x80
[ 359.241034] PGD 3809b067 PUD 3809a067 PMD 0
[ 359.241034] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 359.241034] CPU 1
[ 359.241034] Pid: 2852, comm: sh Tainted: G W 3.3.0-rc5-next-20120227-sasha-dirty #26
[ 359.241034] RIP: 0010:[<ffffffff8110e03d>] [<ffffffff8110e03d>] get_usage_chars+0xd/0x80
[ 359.241034] RSP: 0018:ffff880038825cf8 EFLAGS: 00010086
[ 359.241034] RAX: 0000000000000000 RBX: ffff880038825d18 RCX: 00000000297a2979
[ 359.241034] RDX: 0000000000000000 RSI: ffff880038825d18 RDI: 0000000000000000
[ 359.241034] RBP: ffff880038825d08 R08: 0000000000000000 R09: 0000000000000000
[ 359.241034] R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
[ 359.241034] R13: 0000000000000001 R14: ffff880038825da0 R15: ffff88003cc93000
[ 359.241034] FS: 00007ffd48666700(0000) GS:ffff88003e000000(0000) knlGS:0000000000000000
[ 359.241034] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 359.241034] CR2: 0000000000000030 CR3: 00000000392dc000 CR4: 00000000000406e0
[ 359.241034] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 359.241034] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 359.241034] Process sh (pid: 2852, threadinfo ffff880038824000, task ffff88003cc93000)
[ 359.241034] Stack:
[ 359.241034] ffff880038825d18 0000000000000000 ffff880038825d38 ffffffff8110e0cf
[ 359.241034] ffff880038825da0 ffff88003cc93000 ffff88003d2288e0 0000000000000000
[ 359.241034] ffff880038825d58 ffffffff8110e13e ffff88003d228000 0000000000000001
[ 359.241034] Call Trace:
[ 359.241034] [<ffffffff8110e0cf>] print_lock_name+0x1f/0x50
[ 359.241034] [<ffffffff8110e13e>] print_lock+0x3e/0xb0
[ 359.241034] [<ffffffff8110e22e>] lockdep_print_held_locks+0x7e/0xf0
[ 359.241034] [<ffffffff81115220>] debug_show_all_locks+0x190/0x260
[ 359.241034] [<ffffffff810e47f7>] show_state_filter+0x177/0x220
[ 359.241034] [<ffffffff810e4680>] ? sched_show_task+0x190/0x190
[ 359.241034] [<ffffffff81971d4b>] sysrq_handle_showstate+0xb/0x10
[ 359.241034] [<ffffffff81972209>] __handle_sysrq+0x129/0x190
[ 359.241034] [<ffffffff81972270>] ? __handle_sysrq+0x190/0x190
[ 359.241034] [<ffffffff819722ba>] write_sysrq_trigger+0x4a/0x50
[ 359.241034] [<ffffffff81243c10>] proc_reg_write+0x80/0xc0
[ 359.241034] [<ffffffff811dba86>] vfs_write+0xc6/0x180
[ 359.241034] [<ffffffff811dbc2f>] sys_write+0x4f/0xa0
[ 359.241034] [<ffffffff826e4979>] system_call_fastpath+0x16/0x1b
[ 359.241034] Code: b5 70 ff ff ff e8 34 fb ff ff 48 89 c6 eb ce e8 ea e7 f9 ff 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 54 49 89 fc 53 48 89 f3 <48> 8b 7f 30 31 f6 e8 c8 f0 ff ff be 01 00 00 00 88 03 49 8b 7c
[ 359.241034] RIP [<ffffffff8110e03d>] get_usage_chars+0xd/0x80
[ 359.241034] RSP <ffff880038825cf8>
[ 359.241034] CR2: 0000000000000030
[ 359.241034] ---[ end trace 80d8165bc39af079 ]---
I'll send some patches to prevent the NULL deref itself which happens since a chunk of the code in lockdep.c assumed hlock_class() can't return NULL.
This won't fix the actual problem though, I'm not sure exactly how a held lock wouldn't have a class initialized to it.
--
Sasha.
next reply other threads:[~2012-02-28 13:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-28 15:24 Sasha Levin [this message]
2012-02-28 13:29 ` lockdep: Warning & NULL ptr deref Peter Zijlstra
2012-02-28 14:13 ` Sasha Levin
2012-02-28 14:19 ` Sasha Levin
2012-02-28 14:20 ` Peter Zijlstra
2012-02-28 14:23 ` Sasha Levin
2012-02-28 14:26 ` Peter Zijlstra
2012-02-28 14:55 ` Sasha Levin
2012-02-28 15:08 ` Peter Zijlstra
2012-02-28 16:02 ` Sasha Levin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1330442692.3719.7.camel@lappy \
--to=levinsasha928@gmail.com \
--cc=davej@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.