From: [email protected] (Eric W. Biederman)
To: Linus Torvalds <[email protected]>
Cc: Linux Kernel Mailing List <[email protected]>,
linux-fsdevel <[email protected]>,
io-uring <[email protected]>,
Alexander Viro <[email protected]>,
Olivier Langlois <[email protected]>,
Jens Axboe <[email protected]>,
"Pavel Begunkov\>" <[email protected]>,
Oleg Nesterov <[email protected]>
Subject: Re: [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL
Date: Wed, 09 Jun 2021 15:48:33 -0500 [thread overview]
Message-ID: <8735tq9332.fsf@disp2133> (raw)
In-Reply-To: <CAHk-=wjC7GmCHTkoz2_CkgSc_Cgy19qwSQgJGXz+v2f=KT3UOw@mail.gmail.com> (Linus Torvalds's message of "Wed, 9 Jun 2021 13:33:36 -0700")
Linus Torvalds <[email protected]> writes:
> On Wed, Jun 9, 2021 at 1:17 PM Eric W. Biederman <[email protected]> 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.
It looks like it would need to be:
static bool dump_interrupted(void)
{
return fatal_signal_pending() || freezing();
}
As the original implementation of dump_interrupted 528f827ee0bb
("coredump: introduce dump_interrupted()") is deliberately allowing the
freezer to terminate the core dumps to allow for reliable system
suspend.
>
> 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
next prev parent reply other threads:[~2021-06-09 20:48 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[email protected]>
[not found] ` <[email protected]>
[not found] ` <87h7i694ij.fsf_-_@disp2133>
2021-06-09 20:33 ` [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL Linus Torvalds
2021-06-09 20:48 ` Eric W. Biederman [this message]
2021-06-09 20:52 ` Linus Torvalds
2021-06-09 21:02 ` Olivier Langlois
2021-06-09 21:05 ` Eric W. Biederman
2021-06-09 21:26 ` Olivier Langlois
2021-06-09 21:56 ` Olivier Langlois
2021-06-10 14:26 ` Eric W. Biederman
2021-06-10 15:17 ` Olivier Langlois
2021-06-10 18:58 ` [CFT}[PATCH] coredump: Limit what can interrupt coredumps Eric W. Biederman
2021-06-10 19:10 ` Linus Torvalds
2021-06-10 19:18 ` Eric W. Biederman
2021-06-10 19:50 ` Linus Torvalds
2021-06-10 20:11 ` [PATCH] " Eric W. Biederman
2021-06-10 21:04 ` Linus Torvalds
2021-06-12 14:36 ` Olivier Langlois
2021-06-12 16:26 ` Jens Axboe
2021-06-14 14:10 ` Oleg Nesterov
2021-06-14 16:37 ` Eric W. Biederman
2021-06-14 16:59 ` Oleg Nesterov
2021-06-15 22:08 ` Eric W. Biederman
2021-06-16 19:23 ` Olivier Langlois
2021-06-16 20:00 ` Eric W. Biederman
2021-06-18 20:05 ` Olivier Langlois
2021-08-05 13:06 ` Olivier Langlois
2021-08-10 21:48 ` Tony Battersby
2021-08-11 20:47 ` Olivier Langlois
2021-08-12 1:55 ` Jens Axboe
2021-08-12 13:53 ` Tony Battersby
2021-08-15 20:42 ` Olivier Langlois
2021-08-16 13:02 ` Pavel Begunkov
2021-08-16 13:06 ` Pavel Begunkov
2021-08-17 18:15 ` Jens Axboe
2021-08-17 18:24 ` Jens Axboe
2021-08-17 19:29 ` Tony Battersby
2021-08-17 19:59 ` Jens Axboe
2021-08-17 21:28 ` Jens Axboe
2021-08-17 21:39 ` Tony Battersby
2021-08-17 22:05 ` Jens Axboe
2021-08-18 14:37 ` Tony Battersby
2021-08-18 14:46 ` Jens Axboe
2021-08-18 2:57 ` Jens Axboe
2021-08-18 2:58 ` Jens Axboe
2021-08-21 10:08 ` Olivier Langlois
2021-08-21 16:47 ` Olivier Langlois
2021-08-21 16:51 ` Jens Axboe
2021-08-21 17:21 ` Olivier Langlois
2021-08-21 9:52 ` Olivier Langlois
2021-08-21 9:48 ` Olivier Langlois
2021-10-22 14:13 ` [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL Pavel Begunkov
2021-12-24 1:34 ` Olivier Langlois
2021-12-24 10:37 ` Pavel Begunkov
2021-12-24 19:52 ` Eric W. Biederman
2021-12-28 11:24 ` Pavel Begunkov
2022-03-14 23:58 ` Eric W. Biederman
[not found] ` <[email protected]>
2022-06-01 3:15 ` Jens Axboe
2022-07-20 16:49 ` [PATCH 0/2] coredump: Allow io_uring using apps to dump to pipes Eric W. Biederman
2022-07-20 16:50 ` [PATCH 1/2] signal: Move stopping for the coredump from do_exit into get_signal Eric W. Biederman
2022-07-20 16:51 ` [PATCH 2/2] coredump: Allow coredumps to pipes to work with io_uring Eric W. Biederman
2022-08-22 21:16 ` Olivier Langlois
2022-08-23 3:35 ` Olivier Langlois
2022-08-23 18:22 ` Eric W. Biederman
2022-08-23 18:27 ` Jens Axboe
2022-08-24 15:11 ` Eric W. Biederman
2022-08-24 15:51 ` Jens Axboe
2022-01-05 19:39 ` [RFC] coredump: Do not interrupt dump for TIF_NOTIFY_SIGNAL Olivier Langlois
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8735tq9332.fsf@disp2133 \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox