From: Peter Zijlstra <peterz@infradead.org>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] trace: disable preemption before taking raw spinlocks
Date: Tue, 26 May 2009 23:51:40 +0200 [thread overview]
Message-ID: <1243374700.6600.26.camel@laptop> (raw)
In-Reply-To: <20090526172802.6377e33f@osiris.boeblingen.de.ibm.com>
On Tue, 2009-05-26 at 17:28 +0200, Heiko Carstens wrote:
> From: Heiko Carstens <heiko.carstens@de.ibm.com>
>
> s390 code uses smp_processor_id() in __raw_spin_lock() code which
> reveals that a (raw) spinlock is taken without preemption disabled.
> This can potentially deadlock.
>
> To fix this explicitly disable and enable preemption.
>
> BUG: using smp_processor_id() in preemptible [00000000] code: cat/2278
> caller is trace_find_cmdline+0x40/0xfc
> CPU: 0 Not tainted 2.6.30-rc7-dirty #39
> Process cat (pid: 2278, task: 000000003faedb68, ksp: 000000003b33b988)
> 000000003b33b988 000000003b33bae0 0000000000000002 0000000000000000
> 000000003b33bb80 000000003b33baf8 000000003b33baf8 00000000000175d6
> 0000000000000001 000000003b33b988 000000003f9b0000 000000000000000b
> 000000000000000c 000000003b33bb40 000000003b33bae0 0000000000000000
> 0000000000000000 00000000000175d6 000000003b33bae0 000000003b33bb28
> Call Trace:
> ([<00000000000174b2>] show_trace+0x112/0x170)
> [<0000000000017582>] show_stack+0x72/0x100
> [<0000000000441538>] dump_stack+0xc8/0xd8
> [<000000000025c350>] debug_smp_processor_id+0x114/0x130
> [<00000000000bf0e4>] trace_find_cmdline+0x40/0xfc
> [<00000000000c35d4>] trace_print_context+0x58/0xac
> [<00000000000bb676>] print_trace_line+0x416/0x470
> [<00000000000bc8fe>] s_show+0x4e/0x428
> [<000000000013834e>] seq_read+0x36a/0x5d4
> [<0000000000112a78>] vfs_read+0xc8/0x174
> [<0000000000112c58>] SyS_read+0x74/0xc4
> [<000000000002c7ae>] sysc_noemu+0x10/0x16
> [<000002000012436c>] 0x2000012436c
> 1 lock held by cat/2278:
> #0: (&p->lock){+.+.+.}, at: [<0000000000138056>] seq_read+0x72/0x5d4
Shouldn't that be preempt_disable_notrace() and co to avoid tracer
recursion?
next prev parent reply other threads:[~2009-05-26 21:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-26 15:28 [PATCH] trace: disable preemption before taking raw spinlocks Heiko Carstens
2009-05-26 21:51 ` Peter Zijlstra [this message]
2009-05-26 21:55 ` Steven Rostedt
2009-05-26 21:58 ` Steven Rostedt
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=1243374700.6600.26.camel@laptop \
--to=peterz@infradead.org \
--cc=heiko.carstens@de.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=rostedt@goodmis.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.