Messages in this thread | | | From | Linus Torvalds <> | Date | Wed, 9 Jun 2021 13:33:36 -0700 | Subject | Re: [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL |
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On Wed, Jun 9, 2021 at 1:17 PM Eric W. Biederman <ebiederm@xmission.com> wrote: >> > In short the coredump code deliberately supports being interrupted by > SIGKILL, and depends upon prepare_signal to filter out all other > signals.
Hmm.
I have to say, that looks like the core reason for the bug: if you want to be interrupted by a fatal signal, you shouldn't use signal_pending(), you should use fatal_signal_pending().
Now, the fact that we haven't cleared TIF_NOTIFY_SIGNAL for the first signal is clearly the immediate cause of this, but at the same time I really get the feeling that that coredump aborting code should always had used fatal_signal_pending().
We do want to be able to abort core-dumps (stuck network filesystems is the traditional reason), but the fact that it used signal_pending() looks buggy.
In fact, the very comment in that dump_interrupted() function seems to acknowledge that signal_pending() is all kinds of silly.
So regardless of the fact that io_uring does seem to have messed up this part of signals, I think the fix is not to change signal_pending() to task_sigpending(), but to just do what the comment suggests we should do.
But also:
> With the io_uring code comes an extra test in signal_pending > for TIF_NOTIFY_SIGNAL (which is something about asking a task to run > task_work_run).
Jens, is this still relevant? Maybe we can revert that whole series now, and make the confusing difference between signal_pending() and task_sigpending() go away again?
Linus
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