Messages in this thread | | | Date | Sun, 17 Feb 2013 20:50:44 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 0/3] coredump: fix the ancient signal problems |
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On 02/17, Linus Torvalds wrote: > > On Sun, Feb 17, 2013 at 11:18 AM, Oleg Nesterov <oleg@redhat.com> wrote: > > > > Linus, et al, could you please ack/nack the intent? Of course I will > > appreciate if you can review the code, but what I am actually worried > > about is the user-visible change: the coredumping becomes killable but > > only by the _explicit_ SIGKILL, other fatal signals are "ignored". > > That isn't a problem. In fact, we already have logic that makes the > act of writing a file be killable by SIGKILL (because you really > really want that for network filesystems, for example), so I suspect > that core-dumping was interruptible by SIGKILL even before you made it > explicitly so - simply because the IO itself was.
Yes, and even pipe_write() can fail if signal_pending() == T.
> And even if it wasn't (because maybe the SIGKILL logic doesn't get > triggered due to all the special-case core-dumping code in signal > handling),
Yes, SIGKILL can wakeup (or can miss) the dumping thread sleeping in ->write() but this is not enough. See 2/3.
> SIGKILL really is very very special. Having it kill a > coredump in progress sounds fine to me.
Great.
> That said, I'm not convinced about your particular split of patches. > The first patch introduces that new SIGNAL_GROUP_COREDUMP, and then > the second patch modifies one of the new use cases: > > - tsk->signal->flags |= SIGNAL_GROUP_COREDUMP; > + tsk->signal->flags = SIGNAL_GROUP_COREDUMP; > > > and that just smells to me like you tried too hard to split things > into two patches.
Oh, I disagree, but I wouldn't mind to join these changes assuming they pass the review (including my self-review tomorrow).
To me, the splitting is "natural". 1/3 protects the dumping thread from !SIGKILL signals, 2/3 makes makes the dumping thread killable.
Another reason for 1/3 in a separate patch is the documentation, I think we need more changes in prepare_signal(SIGNAL_GROUP_EXIT) case.
But I won't insist.
> I wonder if Al > Viro hould be on the cc.
Hello Al.
I'll send you mbox with this series privately.
Oleg.
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