Bug#787807: libc6: mq_open unexpectedly fails with errno 24
On Mon, 15 Jun 2015 11:55:47 +0200 Aurelien Jarno aurel...@aurel32.net wrote: Nothing has changed in the libc6 package for sometimes. When does the breakage started? I see you are using a 4.0 kernel, could it be due to that? I made some tests on Debian VMs, that I have flying around. Debian SID with 4.0 (amd64): problem as described above Debian SID with 3.16 (amd64): same problem Debian Wheezy with 3.2.0 (amd64): same problem Debian Wheezy with 3.2.0 (i386): Works as expected (up to maxmsg=1000, with maxmsg=1001 I get errno=22 (Invalid argument) - that's fine for me, but is not what the man page says for this case. BTW the man page for mq_open is broken - double entries below ERRORS). Looks like amd64 architecture has the problem since a while. Tim signature.asc Description: This is a digitally signed message part.
Bug#787807: libc6: mq_open unexpectedly fails with errno 24
On 2015-06-05 11:44, Tim Ruehsen wrote: Package: libc6 Severity: normal Dear Maintainer, I have an application that uses Posix message queues since a while. Today I realized that mq_open fails with errno 24 where it worked before. (errno 24: Too many open files) Nothing has changed in the libc6 package for sometimes. When does the breakage started? I see you are using a 4.0 kernel, could it be due to that? Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net -- To UNSUBSCRIBE, email to debian-glibc-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20150615095547.ga10...@aurel32.net
Bug#787807: libc6: mq_open unexpectedly fails with errno 24
On 2015-06-15 14:55, Aurelien Jarno wrote: On 2015-06-15 12:32, Tim Ruehsen wrote: On Mon, 15 Jun 2015 11:55:47 +0200 Aurelien Jarno aurel...@aurel32.net wrote: Nothing has changed in the libc6 package for sometimes. When does the breakage started? I see you are using a 4.0 kernel, could it be due to that? I made some tests on Debian VMs, that I have flying around. Debian SID with 4.0 (amd64): problem as described above Debian SID with 3.16 (amd64): same problem Debian Wheezy with 3.2.0 (amd64): same problem Debian Wheezy with 3.2.0 (i386): Works as expected (up to maxmsg=1000, with maxmsg=1001 I get errno=22 (Invalid argument) - that's fine for me, but is not what the man page says for this case. Well it looks like it matches the manpage: | O_CREAT was specified in oflag, and attr was not NULL, but | attr-mq_maxmsg or attr-mq_msqsize was invalid. In a process that is | unprivileged (does not have the CAP_SYS_RESOURCE capability), | attr-mq_maxmsg must be less than or equal to the msg_max limit, and | attr-mq_msgsize must be less than or equal to the msgsize_max limit. BTW the man page for mq_open is broken - double entries below ERRORS). The manpage is nor provided by the glibc, but by the Linux man-pages project. Please report the bug there. Looks like amd64 architecture has the problem since a while. I don't really know what is the problem, but a strace shows that the glibc just returns the errno from the kernel. What does ulimit -q returns on your system? It seems to be 819200 by default, which is why the kernel refuses to create the message queue. Here increasing the value allows the msg queue to be created successfully. The way to compute the limit is described in the getrlimit(2) manpage. Note that the value includes size of structures, which are likely to be different on i386 and amd64, and has changed starting with kernel 3.5. It's therefore likely that by using an amd64 machine and a recent kernel, you crossed the 819200 limit. -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net signature.asc Description: Digital signature
Bug#787807: libc6: mq_open unexpectedly fails with errno 24
On 2015-06-15 12:32, Tim Ruehsen wrote: On Mon, 15 Jun 2015 11:55:47 +0200 Aurelien Jarno aurel...@aurel32.net wrote: Nothing has changed in the libc6 package for sometimes. When does the breakage started? I see you are using a 4.0 kernel, could it be due to that? I made some tests on Debian VMs, that I have flying around. Debian SID with 4.0 (amd64): problem as described above Debian SID with 3.16 (amd64): same problem Debian Wheezy with 3.2.0 (amd64): same problem Debian Wheezy with 3.2.0 (i386): Works as expected (up to maxmsg=1000, with maxmsg=1001 I get errno=22 (Invalid argument) - that's fine for me, but is not what the man page says for this case. Well it looks like it matches the manpage: | O_CREAT was specified in oflag, and attr was not NULL, but | attr-mq_maxmsg or attr-mq_msqsize was invalid. In a process that is | unprivileged (does not have the CAP_SYS_RESOURCE capability), | attr-mq_maxmsg must be less than or equal to the msg_max limit, and | attr-mq_msgsize must be less than or equal to the msgsize_max limit. BTW the man page for mq_open is broken - double entries below ERRORS). The manpage is nor provided by the glibc, but by the Linux man-pages project. Please report the bug there. Looks like amd64 architecture has the problem since a while. I don't really know what is the problem, but a strace shows that the glibc just returns the errno from the kernel. -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net signature.asc Description: Digital signature
Bug#787807: libc6: mq_open unexpectedly fails with errno 24
On Monday 15 June 2015 15:21:52 Aurelien Jarno wrote: I made some tests on Debian VMs, that I have flying around. Debian SID with 4.0 (amd64): problem as described above Debian SID with 3.16 (amd64): same problem Debian Wheezy with 3.2.0 (amd64): same problem Debian Wheezy with 3.2.0 (i386): Works as expected (up to maxmsg=1000, with maxmsg=1001 I get errno=22 (Invalid argument) - that's fine for me, but is not what the man page says for this case. Ok, forget about the man pages. I was just puzzled by multiple entries per error number. Looks like amd64 architecture has the problem since a while. I don't really know what is the problem, but a strace shows that the glibc just returns the errno from the kernel. What does ulimit -q returns on your system? It seems to be 819200 by default, which is why the kernel refuses to create the message queue. Yes, it is 819200 on i386 (Wheezy) and on amd64 (SID) here. Here increasing the value allows the msg queue to be created successfully. The way to compute the limit is described in the getrlimit(2) manpage. Note that the value includes size of structures, which are likely to be different on i386 and amd64, and has changed starting with kernel 3.5. It's therefore likely that by using an amd64 machine and a recent kernel, you crossed the 819200 limit. Woooh, thanks for that hint ! Wouldn't have thought about this for a while... BTW, using /etc/security/limits.conf to increase that value (tried hard, soft, - for * and for the user) does not increase the users ulimit value (nor permits him to increase it via ulimit). But that is another story... did not test a reboot yet. Many thanks for your help. I guess you can close this bug. Best Regards Tim signature.asc Description: This is a digitally signed message part.
Bug#787807: libc6: mq_open unexpectedly fails with errno 24
Package: libc6
Severity: normal
Dear Maintainer,
I have an application that uses Posix message queues since a while.
Today I realized that mq_open fails with errno 24 where it worked before.
(errno 24: Too many open files)
Here is a short C file to reproduce the problem.
Before you start it, you have to increase msg_max system default:
sysctl -w fs.mqueue.msg_max=1000
Now (as normal user) execute the following code:
#include stdio.h
#include mqueue.h
#include errno.h
void main(void) {
struct mq_attr attr={.mq_maxmsg=900,.mq_msgsize=1020};
int rc=mq_open(/xxx,O_CREAT | O_RDONLY, 0600, attr);
printf(rc=%d errno=%d\n,rc,errno);
}
It returns errno 24. Using a value of 800 for .mq_maxmsg returns success.
Compile with gcc x.c -o x -lrt.
The system settings should allow the above values without problem:
$ ls /proc/sys/fs/mqueue/|more
msg_default
msg_max
msgsize_default
msgsize_max
queues_max
$ cat /proc/sys/fs/mqueue/*
10
1000
8192
8192
256
Regards, Tim
-- System Information:
Debian Release: stretch/sid
APT prefers unstable
APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 4.0.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) (ignored: LC_ALL
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Init: systemd (via /run/systemd/system)
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