From: Olivier Langlois <olivier@trillion01.com>
To: Jens Axboe <axboe@kernel.dk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Stefan Metzmacher <metze@samba.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
io-uring <io-uring@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [PATCH] io_thread/x86: don't reset 'cs', 'ss', 'ds' and 'es' registers for io_threads
Date: Wed, 12 May 2021 00:24:32 -0400 [thread overview]
Message-ID: <17471c9fec18765449ef3a5a4cddc23561b97f52.camel@trillion01.com> (raw)
In-Reply-To: <59ea3b5a-d7b3-b62e-cc83-1f32a83c4ac2@kernel.dk>
On Mon, 2021-05-03 at 20:50 -0600, Jens Axboe wrote:
>
> I tested the below, which is the two combined, with a case that
> deliberately has two types of io threads - one for SQPOLL submission,
> and one that was created due to async work being needed. gdb attaches
> just fine to the creator, with a slight complaint:
>
> Attaching to process 370
> [New LWP 371]
> [New LWP 372]
> Error while reading shared library symbols for
> /usr/lib/libpthread.so.0:
> Cannot find user-level thread for LWP 372: generic error
> 0x00007f1a74675125 in clock_nanosleep@GLIBC_2.2.5 () from
> /usr/lib/libc.so.6
> (gdb) info threads
> Id Target Id Frame
> * 1 LWP 370 "io_uring" 0x00007f1a74675125 in
> clock_nanosleep@GLIBC_2.2.5 ()
> from /usr/lib/libc.so.6
> 2 LWP 371 "iou-sqp-370" 0x00007f1a746a7a9d in syscall () from
> /usr/lib/libc.so.6
> 3 LWP 372 "io_uring" 0x00007f1a74675125 in
> clock_nanosleep@GLIBC_2.2.5 ()
> from /usr/lib/libc.so.6
>
> (gdb) thread 2
> [Switching to thread 2 (LWP 371)]
> #0 0x00007f1a746a7a9d in syscall () from /usr/lib/libc.so.6
> (gdb) bt
> #0 0x00007f1a746a7a9d in syscall () from /usr/lib/libc.so.6
> Backtrace stopped: Cannot access memory at address 0x0
>
> (gdb) thread 1
> [Switching to thread 1 (LWP 370)]
> #0 0x00007f1a74675125 in clock_nanosleep@GLIBC_2.2.5 () from
> /usr/lib/libc.so.6
> (gdb) bt
> #0 0x00007f1a74675125 in clock_nanosleep@GLIBC_2.2.5 () from
> /usr/lib/libc.so.6
> #1 0x00007f1a7467a357 in nanosleep () from /usr/lib/libc.so.6
> #2 0x00007f1a7467a28e in sleep () from /usr/lib/libc.so.6
> #3 0x000055bd41e929ba in main (argc=<optimized out>, argv=<optimized
> out>)
> at t/io_uring.c:658
>
> which looks very reasonable to me - no backtraces for the io threads,
> and
> no arch complaints.
>
I have reported an issue that I have with a user process using io_uring
where when it core dumps, the dump fails to be generated.
https://github.com/axboe/liburing/issues/346
Pavel did comment to my report and he did point out this thread as
possibly a related issue.
I'm far from being 100% convinced that Stefan patch can help but I am
going to give it a try and report back here if it does help.
Greetings,
Olivier
next prev parent reply other threads:[~2021-05-12 5:24 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <8735v3ex3h.ffs@nanos.tec.linutronix.de>
2021-05-03 16:05 ` [PATCH] io_thread/x86: don't reset 'cs', 'ss', 'ds' and 'es' registers for io_threads Andy Lutomirski
2021-05-03 19:14 ` Linus Torvalds
2021-05-03 20:15 ` Andy Lutomirski
2021-05-03 20:21 ` Andy Lutomirski
2021-05-03 20:37 ` Linus Torvalds
2021-05-03 21:26 ` Jens Axboe
2021-05-03 21:49 ` Andy Lutomirski
2021-05-03 22:08 ` Linus Torvalds
2021-05-03 22:56 ` Thomas Gleixner
2021-05-03 23:15 ` Andy Lutomirski
2021-05-03 23:16 ` Linus Torvalds
2021-05-03 23:19 ` Linus Torvalds
2021-05-03 23:27 ` Stefan Metzmacher
2021-05-03 23:48 ` Linus Torvalds
2021-05-04 2:50 ` Jens Axboe
2021-05-04 11:39 ` Stefan Metzmacher
2021-05-04 15:53 ` Linus Torvalds
2021-05-12 4:24 ` Olivier Langlois [this message]
2021-05-12 17:44 ` Linus Torvalds
2021-05-12 20:55 ` Jens Axboe
2021-05-20 4:13 ` Olivier Langlois
2021-05-21 7:31 ` Olivier Langlois
2021-05-25 19:39 ` Olivier Langlois
2021-05-25 19:45 ` Olivier Langlois
2021-05-25 19:52 ` Jens Axboe
2021-05-25 20:23 ` Linus Torvalds
2021-05-04 8:22 ` David Laight
2021-05-04 0:01 ` Andy Lutomirski
2021-05-04 8:39 ` Peter Zijlstra
2021-05-04 15:35 ` Borislav Petkov
2021-05-04 15:55 ` Simon Marchi
2021-05-05 11:29 ` Stefan Metzmacher
2021-05-05 21:59 ` Simon Marchi
2021-05-05 22:11 ` Andy Lutomirski
2021-05-05 23:12 ` Borislav Petkov
2021-05-05 23:22 ` Andy Lutomirski
2021-05-06 1:04 ` Simon Marchi
2021-05-06 15:11 ` Andy Lutomirski
2021-05-06 9:47 ` David Laight
2021-05-06 9:53 ` David Laight
2021-05-05 22:21 ` Stefan Metzmacher
2021-05-05 23:15 ` Simon Marchi
2021-04-11 15:27 Stefan Metzmacher
2021-04-14 21:28 ` Stefan Metzmacher
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