linux-kernel - Re: perf: stalls in perf_install_in_context/perf_remove_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151215133947.GG6357@twins.programming.kicks-ass.net>
Date:	Tue, 15 Dec 2015 14:39:47 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Eric Dumazet <edumazet@...gle.com>
Subject: Re: perf: stalls in perf_install_in_context/perf_remove_from_context

On Tue, Dec 15, 2015 at 02:01:32PM +0100, Dmitry Vyukov wrote:


> Call Trace:
>  <IRQ>  [<ffffffff810e5e38>] sched_show_task+0x148/0x250 kernel/sched/core.c:4934

 <snip>

>  [<ffffffff823ff46c>] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:520
>
>  <EOI>  [<     inline     >] ? arch_local_irq_enable ./arch/x86/include/asm/paravirt.h:816
>  <EOI>  [<     inline     >] ? __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:170
>  <EOI>  [<ffffffff823fde9e>] ? _raw_spin_unlock_irq+0x2e/0x40 kernel/locking/spinlock.c:199
>  [<     inline     >] ? __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:170
>  [<ffffffff823fde97>] ? _raw_spin_unlock_irq+0x27/0x40 kernel/locking/spinlock.c:199
>  [<ffffffff8119c8bb>] perf_install_in_context+0x6b/0xf0 kernel/events/core.c:2173
>  [<ffffffff811a492c>] SYSC_perf_event_open+0x63c/0xe40 kernel/events/core.c:8565
>  [<ffffffff811a7739>] SyS_perf_event_open+0x9/0x10 kernel/events/core.c:8261
>  [<ffffffff823fe676>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185


So this looks like its stuck in the retry loop in
perf_install_in_context(). We do the raw_spin_unlock_irq(), which allows
the above watchdog interrupt to happen, but make no progress.

This means the task_function_call() thing keeps failing, which is
extremely unlikely.

Let me have a play with your test-case to see if it reproduces.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/