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From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Wen Yang <wen.yang99@zte.com.cn>, majiang <ma.jiang@zte.com.cn>
Subject: Re: [PATCH v3 20/20] signal: Don't restart fork when signals come in.
Date: Thu, 26 Jul 2018 18:21:44 +0200	[thread overview]
Message-ID: <20180726162144.GC32718@redhat.com> (raw)
In-Reply-To: <87k1pk2cj9.fsf_-_@xmission.com>

On 07/24, Eric W. Biederman wrote:
>
> Similarly the current code will also miss blocked
> signals that are delivered to multiple process, as those signals will
> not appear pending during fork.

Well, I still think this needs a separate change and discussion...

Let me repeat, I simply do not know if this is good or not, I don't know
if the current behaviour is by design or it is mistake.

OK, I won't argue but note that your patch doesn't really fix the problem,

> +	spin_lock_irq(&current->sighand->siglock);
> +	if (!(clone_flags & CLONE_THREAD))
> +		hlist_add_head(&delayed.node, &current->signal->multiprocess);
> +	recalc_sigpending();
> +	spin_unlock_irq(&current->sighand->siglock);
> +	retval = -ERESTARTNOINTR;
> +	if (signal_pending(current))
> +		goto fork_out;

because recalc_sigpending() will not notice the blocked multiprocess signal
if it is already pending.

Oleg.


  parent reply	other threads:[~2018-07-26 16:21 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-200447-5873-b2kAsSyE1X@https.bugzilla.kernel.org/>
     [not found] ` <CA+55aFyOaEGc_wjRuAxYZH7D4zi4xUQTqUwMmUzxFJQ__2pXuQ@mail.gmail.com>
     [not found]   ` <87h8l9p7bg.fsf@xmission.com>
     [not found]     ` <20180709104158.GA23796@redhat.com>
     [not found]       ` <87sh4so5jv.fsf@xmission.com>
     [not found]         ` <20180709145726.GA26149@redhat.com>
     [not found]           ` <877em4nxo0.fsf@xmission.com>
     [not found]             ` <CA+55aFwq90_KeRUesktap7L_4Hp3gatKZ28RYw1jXBYeOqUoeA@mail.gmail.com>
     [not found]               ` <87lgakm4ol.fsf@xmission.com>
     [not found]                 ` <CA+55aFz1XFvOgJySKVNQD9VS4hys0J7rozxqd3s5ND0z80tfVw@mail.gmail.com>
     [not found]                   ` <20180710134639.GA2453@redhat.com>
2018-07-10 16:00                     ` [Bug 200447] infinite loop in fork syscall Eric W. Biederman
2018-07-11 12:08                       ` Oleg Nesterov
     [not found]                     ` <CA+55aFxcjSYAj-CZFEuDwiwZyMg+prV_jeP_Vuh06RJA0BboSw@mail.gmail.com>
2018-07-11  2:41                       ` [RFC][PATCH 0/11] PIDTYPE_TGID and fewer fork restarts Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 01/11] pids: Initialize leader_pid in init_task Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 02/11] pids: Move task_pid_type into sched/signal.h Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 03/11] pids: Compute task_tgid using signal->leader_pid Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 04/11] kvm: Don't open code task_pid in kvm_vcpu_ioctl Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 05/11] pids: Move the pgrp and session pid pointers from task_struct to signal_struct Eric W. Biederman
2018-07-17 11:59                           ` Oleg Nesterov
2018-07-11  2:44                         ` [RFC][PATCH 06/11] pid: Implement PIDTYPE_TGID Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 07/11] signal: Deliver group signals via PIDTYPE_TGID not PIDTYPE_PID Eric W. Biederman
2018-07-16 12:51                           ` Oleg Nesterov
2018-07-16 14:50                             ` Eric W. Biederman
2018-07-16 17:17                               ` Linus Torvalds
2018-07-16 18:01                                 ` Eric W. Biederman
2018-07-16 18:40                                   ` Linus Torvalds
2018-07-17  9:56                                   ` Oleg Nesterov
2018-07-17 10:18                                     ` Oleg Nesterov
2018-07-20 23:41                                       ` Eric W. Biederman
2018-07-17 16:38                               ` Linus Torvalds
2018-07-20 23:27                                 ` Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 08/11] signal: Use PIDTYPE_TGID to clearly store where file signals will be sent Eric W. Biederman
2018-07-11  2:44                         ` [RFC][PATCH 09/11] tty_io: Use do_send_sig_info in __do_SACK to forcibly kill tasks Eric W. Biederman
2018-07-16 14:55                           ` Oleg Nesterov
2018-07-16 15:08                             ` Eric W. Biederman
2018-07-16 16:50                               ` Linus Torvalds
2018-07-16 19:17                                 ` Eric W. Biederman
2018-07-16 19:36                                   ` Linus Torvalds
2018-07-17  1:48                                     ` Eric W. Biederman
2018-07-17 10:58                               ` Oleg Nesterov
2018-07-11  2:44                         ` [RFC][PATCH 10/11] signal: Push pid type from signal senders down into __send_signal Eric W. Biederman
2018-07-11  3:11                           ` Linus Torvalds
2018-07-11  2:44                         ` [RFC][PATCH 11/11] signal: Ignore all but multi-process signals that come in during fork Eric W. Biederman
2018-07-11 14:14                           ` Oleg Nesterov
2018-07-11 16:02                             ` Eric W. Biederman
2018-07-12 13:42                               ` Oleg Nesterov
2018-07-12 17:11                                 ` Eric W. Biederman
2018-07-13 14:51                             ` Eric W. Biederman
2018-07-24  3:22                         ` [PATCH 00/20] PIDTYPE_TGID removal of fork restarts Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 01/20] pids: Initialize leader_pid in init_task Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 02/20] pids: Move task_pid_type into sched/signal.h Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 03/20] pids: Compute task_tgid using signal->leader_pid Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 04/20] kvm: Don't open code task_pid in kvm_vcpu_ioctl Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 05/20] pids: Move the pgrp and session pid pointers from task_struct to signal_struct Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 06/20] pid: Implement PIDTYPE_TGID Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 07/20] signal: Use PIDTYPE_TGID to clearly store where file signals will be sent Eric W. Biederman
2018-08-16  4:04                             ` [PATCH] signal: Don't send signals to tasks that don't exist Eric W. Biederman
2018-08-17 17:34                               ` Dmitry Vyukov
2018-08-17 18:46                                 ` Eric W. Biederman
2018-08-17 19:24                                   ` Andrew Morton
2018-08-18  5:51                                     ` Eric W. Biederman
2018-08-20 19:26                                       ` J. Bruce Fields
2018-07-24  3:24                           ` [PATCH 08/20] posix-timers: Noralize good_sigevent Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 09/20] signal: Pass pid and pid type into send_sigqueue Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 10/20] signal: Pass pid type into group_send_sig_info Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 11/20] signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 12/20] signal: Pass pid type into do_send_sig_info Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 13/20] signal: Push pid type down into send_signal Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 14/20] signal: Push pid type down into __send_signal Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 15/20] signal: Push pid type down into complete_signal Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 16/20] fork: Move and describe why the code examines PIDNS_ADDING Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 17/20] fork: Unconditionally exit if a fatal signal is pending Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 18/20] signal: Add calculate_sigpending() Eric W. Biederman
2018-07-26 13:20                             ` Oleg Nesterov
2018-07-26 15:13                               ` Eric W. Biederman
2018-07-26 16:24                                 ` Oleg Nesterov
2018-07-24  3:24                           ` [PATCH 19/20] fork: Have new threads join on-going signal group stops Eric W. Biederman
2018-07-24  3:24                           ` [PATCH 20/20] signal: Don't restart fork when signals come in Eric W. Biederman
2018-07-24 17:27                             ` Linus Torvalds
2018-07-24 17:58                               ` Eric W. Biederman
2018-07-24 18:29                                 ` Linus Torvalds
2018-07-24 20:05                                   ` Eric W. Biederman
2018-07-24 20:15                                     ` Linus Torvalds
2018-07-24 20:40                                       ` [PATCH v2 " Eric W. Biederman
2018-07-24 20:56                                         ` Linus Torvalds
2018-07-24 21:24                                           ` Eric W. Biederman
2018-07-25  3:56                                             ` [PATCH v3 " Eric W. Biederman
2018-07-26 13:41                                               ` Oleg Nesterov
2018-07-26 14:42                                                 ` Eric W. Biederman
2018-07-26 15:55                                                   ` Oleg Nesterov
2018-08-09  6:19                                                     ` Eric W. Biederman
2018-07-26 16:21                                               ` Oleg Nesterov [this message]
2018-07-24 17:29                           ` [PATCH 00/20] PIDTYPE_TGID removal of fork restarts Linus Torvalds
2018-07-25 16:05                           ` Oleg Nesterov
2018-07-25 16:58                             ` Eric W. Biederman
2018-08-09  6:53                           ` [PATCH v5 0/6] Not restarting for due to signals Eric W. Biederman
2018-08-09  6:56                             ` [PATCH v5 1/6] fork: Move and describe why the code examines PIDNS_ADDING Eric W. Biederman
2018-08-09  6:56                             ` [PATCH v5 2/6] fork: Unconditionally exit if a fatal signal is pending Eric W. Biederman
2018-08-09  6:56                             ` [PATCH v5 3/6] signal: Add calculate_sigpending() Eric W. Biederman
2018-08-09  6:56                             ` [PATCH v5 4/6] fork: Skip setting TIF_SIGPENDING in ptrace_init_task Eric W. Biederman
2018-08-09  6:56                             ` [PATCH v5 5/6] fork: Have new threads join on-going signal group stops Eric W. Biederman
2018-08-09  6:56                             ` [PATCH v5 6/6] signal: Don't restart fork when signals come in Eric W. Biederman
2018-08-09 17:15                               ` Linus Torvalds
2018-08-09 17:42                                 ` Eric W. Biederman
2018-08-09 18:09                                 ` [PATCH v6 " Eric W. Biederman
2018-08-09 17:16                             ` [PATCH v5 0/6] Not restarting for due to signals Linus Torvalds

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