From: Josh Triplett <josh@joshtriplett.org> To: Oleg Nesterov <oleg@redhat.com> Cc: Thiago Macieira <thiago.macieira@intel.com>, Al Viro <viro@zeniv.linux.org.uk>, Andrew Morton <akpm@linux-foundation.org>, Andy Lutomirski <luto@amacapital.net>, Ingo Molnar <mingo@redhat.com>, Kees Cook <keescook@chromium.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, "H. Peter Anvin" <hpa@zytor.com>, Rik van Riel <riel@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Michael Kerrisk <mtk.manpages@gmail.com>, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 6/6] clone4: Introduce new CLONE_FD flag to get task exit notification via fd Date: Sat, 14 Mar 2015 15:14:18 -0700 [thread overview] Message-ID: <20150314221417.GK22130@thin> (raw) In-Reply-To: <20150314203029.GA11656@redhat.com> On Sat, Mar 14, 2015 at 09:30:29PM +0100, Oleg Nesterov wrote: > On 03/14, Josh Triplett wrote: > > > > What I was proposing was that a task that isn't yet dead, but that is > > going to be autoreaped, is not eligible for waiting either. All the > > various wait* familiy of system calls should pretend it doesn't exist at > > all, because returning an autoreaped task from a wait* call introduces a > > race condition if the parent tries to *do* anything with the returned > > PID. If you launch a process with CLONE_FD, you need to manage it > > exclusively with that fd, not with the wait* family of system calls. > > > > That also implies that the child-stop and child-continued mechanisms > > (do_notify_parent_cldstop, WSTOPPED, WCONTINUED) should ignore the task > > too. In the future there could be a flag to clone4 that lets you get > > stop and continue notifications through the file descriptor. > > So far I strongly disagree, and I think that "autoreap" feature should > not depend on CLONE_FD. After reading your other mail and thinking about this, I agree that the two can be separated; see my othermail for the details. > Plus we should also discuss the reparenting. Ok, let me leave this > discussion until I read 0/4 at least. I think you can safely wait for v2 of the last patch, though the first four patches should be almost completely identical in v2. - Josh Triplett
WARNING: multiple messages have this Message-ID (diff)
From: Josh Triplett <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org> To: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: Thiago Macieira <thiago.macieira-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, "Paul E. McKenney" <paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Rik van Riel <riel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Michael Kerrisk <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Subject: Re: [PATCH 6/6] clone4: Introduce new CLONE_FD flag to get task exit notification via fd Date: Sat, 14 Mar 2015 15:14:18 -0700 [thread overview] Message-ID: <20150314221417.GK22130@thin> (raw) In-Reply-To: <20150314203029.GA11656-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> On Sat, Mar 14, 2015 at 09:30:29PM +0100, Oleg Nesterov wrote: > On 03/14, Josh Triplett wrote: > > > > What I was proposing was that a task that isn't yet dead, but that is > > going to be autoreaped, is not eligible for waiting either. All the > > various wait* familiy of system calls should pretend it doesn't exist at > > all, because returning an autoreaped task from a wait* call introduces a > > race condition if the parent tries to *do* anything with the returned > > PID. If you launch a process with CLONE_FD, you need to manage it > > exclusively with that fd, not with the wait* family of system calls. > > > > That also implies that the child-stop and child-continued mechanisms > > (do_notify_parent_cldstop, WSTOPPED, WCONTINUED) should ignore the task > > too. In the future there could be a flag to clone4 that lets you get > > stop and continue notifications through the file descriptor. > > So far I strongly disagree, and I think that "autoreap" feature should > not depend on CLONE_FD. After reading your other mail and thinking about this, I agree that the two can be separated; see my othermail for the details. > Plus we should also discuss the reparenting. Ok, let me leave this > discussion until I read 0/4 at least. I think you can safely wait for v2 of the last patch, though the first four patches should be almost completely identical in v2. - Josh Triplett
next prev parent reply other threads:[~2015-03-14 22:14 UTC|newest] Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-03-13 1:40 [PATCH 0/6] CLONE_FD: Task exit notification via file descriptor Josh Triplett 2015-03-13 1:40 ` Josh Triplett 2015-03-13 1:40 ` [PATCH 1/6] clone: Support passing tls argument via C rather than pt_regs magic Josh Triplett 2015-03-13 1:40 ` [PATCH 2/6] x86: Opt into HAVE_COPY_THREAD_TLS, for both 32-bit and 64-bit Josh Triplett 2015-03-13 1:40 ` Josh Triplett 2015-03-13 22:01 ` Andy Lutomirski 2015-03-13 22:01 ` Andy Lutomirski 2015-03-13 22:31 ` josh 2015-03-13 22:38 ` Andy Lutomirski 2015-03-13 22:43 ` josh 2015-03-13 22:43 ` josh-iaAMLnmF4UmaiuxdJuQwMA 2015-03-13 22:45 ` Andy Lutomirski 2015-03-13 22:45 ` Andy Lutomirski 2015-03-13 23:01 ` josh 2015-03-13 23:01 ` josh-iaAMLnmF4UmaiuxdJuQwMA 2015-03-13 1:40 ` [PATCH 3/6] Introduce a new clone4 syscall with more flag bits and extensible arguments Josh Triplett 2015-03-13 1:40 ` [PATCH 4/6] signal: Factor out a helper function to process task_struct exit_code Josh Triplett 2015-03-13 1:40 ` [PATCH 5/6] fs: Make alloc_fd non-private Josh Triplett 2015-03-13 1:40 ` Josh Triplett 2015-03-13 1:41 ` [PATCH 6/6] clone4: Introduce new CLONE_FD flag to get task exit notification via fd Josh Triplett 2015-03-13 16:21 ` Oleg Nesterov 2015-03-13 19:57 ` josh 2015-03-13 21:34 ` Andy Lutomirski 2015-03-13 21:34 ` Andy Lutomirski 2015-03-13 22:20 ` josh 2015-03-13 22:28 ` Andy Lutomirski 2015-03-13 22:28 ` Andy Lutomirski 2015-03-13 22:34 ` josh 2015-03-13 22:34 ` josh-iaAMLnmF4UmaiuxdJuQwMA 2015-03-13 22:38 ` Andy Lutomirski 2015-03-14 14:14 ` Oleg Nesterov 2015-03-14 14:14 ` Oleg Nesterov 2015-03-14 14:32 ` Oleg Nesterov 2015-03-14 14:32 ` Oleg Nesterov 2015-03-14 18:38 ` Thiago Macieira 2015-03-14 18:54 ` Oleg Nesterov 2015-03-14 22:03 ` Josh Triplett 2015-03-14 22:03 ` Josh Triplett 2015-03-14 22:26 ` Thiago Macieira 2015-03-14 19:01 ` Josh Triplett 2015-03-14 19:18 ` Oleg Nesterov 2015-03-14 19:18 ` Oleg Nesterov 2015-03-14 19:47 ` Oleg Nesterov 2015-03-14 19:47 ` Oleg Nesterov 2015-03-14 20:14 ` Josh Triplett 2015-03-14 20:14 ` Josh Triplett 2015-03-14 20:30 ` Oleg Nesterov 2015-03-14 22:14 ` Josh Triplett [this message] 2015-03-14 22:14 ` Josh Triplett 2015-03-14 20:03 ` Josh Triplett 2015-03-14 20:03 ` Josh Triplett 2015-03-14 20:20 ` Oleg Nesterov 2015-03-14 22:09 ` Josh Triplett 2015-03-14 14:35 ` Oleg Nesterov 2015-03-14 14:35 ` Oleg Nesterov 2015-03-14 19:15 ` Josh Triplett 2015-03-14 19:15 ` Josh Triplett 2015-03-14 19:24 ` Oleg Nesterov 2015-03-14 19:48 ` Josh Triplett 2015-03-14 19:48 ` Josh Triplett 2015-03-13 1:41 ` [PATCH] clone4.2: New manpage documenting clone4(2) Josh Triplett 2015-03-13 2:07 ` [PATCH 0/6] CLONE_FD: Task exit notification via file descriptor Thiago Macieira 2015-03-13 2:07 ` Thiago Macieira 2015-03-13 16:05 ` David Drysdale 2015-03-13 16:05 ` David Drysdale 2015-03-13 19:42 ` Josh Triplett 2015-03-13 21:16 ` Thiago Macieira 2015-03-13 21:44 ` josh 2015-03-13 21:33 ` Andy Lutomirski 2015-03-13 21:45 ` josh 2015-03-13 21:45 ` josh-iaAMLnmF4UmaiuxdJuQwMA 2015-03-13 21:51 ` Andy Lutomirski 2015-03-13 21:51 ` Andy Lutomirski 2015-03-14 1:11 ` Thiago Macieira 2015-03-14 1:11 ` Thiago Macieira 2015-03-14 19:03 ` Thiago Macieira 2015-03-14 19:29 ` Josh Triplett 2015-03-14 19:29 ` Josh Triplett 2015-03-15 10:18 ` David Drysdale 2015-03-15 10:18 ` David Drysdale 2015-03-15 10:59 ` Josh Triplett 2015-03-15 8:55 ` David Drysdale 2015-03-15 8:55 ` David Drysdale
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