Re: [PATCH 1/2] ptrace: make wait_on_bit(JOBCTL_TRAPPING_BIT) in ptrace_attach() killable

From	Tejun Heo <tj@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] ptrace: make wait_on_bit(JOBCTL_TRAPPING_BIT) in ptrace_attach() killable
Date	2015-11-24 00:10 +0100
Message-ID	<qy8pc-8rU-7@gated-at.bofh.it> (permalink)
References	<qsWoF-89v-3@gated-at.bofh.it> <qwCro-4G9-3@gated-at.bofh.it> <qwCrp-4G9-39@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Thu, Nov 19, 2015 at 07:47:32PM +0100, Oleg Nesterov wrote:
> ptrace_attach() can hang waiting for STOPPED -> TRACED transition if the
> tracee gets frozen in between, change wait_on_bit() to use TASK_KILLABLE.
> 
> This doesn't really solve the problem(s) and we probably need to fix the
> freezer. In particular, note that this means that pm freezer will fail if
> it races attach-to-stopped-task.
> 
> And otoh perhaps we can just remove JOBCTL_TRAPPING_BIT altogether, it is
> not clear if we really need to hide this transition from debugger, WNOHANG
> after PTRACE_ATTACH can fail anyway if it races with SIGCONT.
> 
> Reported-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 1/2] ptrace: make wait_on_bit(JOBCTL_TRAPPING_BIT) in  ptrace_attach() killable Oleg Nesterov <oleg@redhat.com> - 2015-11-19 19:50 +0100
  Re: [PATCH 1/2] ptrace: make wait_on_bit(JOBCTL_TRAPPING_BIT) in  ptrace_attach() killable Tejun Heo <tj@kernel.org> - 2015-11-24 00:10 +0100

csiph-web