linux-kernel - Re: Could not set non-blocking flag with 2.6.24-rc5

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Message-id: <47634157.7080004@shaw.ca>
Date:	Fri, 14 Dec 2007 20:52:07 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	tino.keitel@....de
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Could not set non-blocking flag with 2.6.24-rc5

Tino Keitel wrote:
> Hi folks,
> 
> I often build Debian packages inside a chroot. Today I discovered a
> failure during an "aptitude update", which is a command to download new
> package lists for the package management. In strace, the lines around
> the failure look like this:
> 
> 99% [Working])         = 14 14
> [pid  5986] select(6, [3 4 5], [], NULL, {0, 500000}) = 0 (Timeout)
> [pid  5986] gettimeofday({1197576353, 670510}, NULL) = 0
> [pid  5986] rt_sigprocmask(SIG_BLOCK, [WINCH], [], 8) = 0
> [pid  5986] rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
> 99% [Working])         = 14 14
> [pid  5986] select(6, [3 4 5], [], NULL, {0, 500000}) = 0 (Timeout)
> [pid  5986] gettimeofday({1197576354, 173902}, NULL) = 0
> [pid  5986] rt_sigprocmask(SIG_BLOCK, [WINCH], [], 8) = 0
> [pid  5986] rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
> 99% [Working])         = 14 14
> [pid  5986] select(6, [3 4 5], [], NULL, {0, 500000} <unfinished ...>
> [pid  5988] <... select resumed> )      = 1 (in [3], left {105, 0})
> [pid  5988] read(3, "", 56559)          = 0
> [pid  5988] fcntl64(-1, F_GETFL)        = -1 EBADF (Bad file
> descriptor)
> [pid  5988] fcntl64(-1, F_SETFL,
> O_ACCMODE|O_CREAT|O_EXCL|O_NOCTTY|O_TRUNC|O_APPEND|O_SYNC|O_ASYNC|O_DIRECT|O_LARGEFILE|O_DIRECTORY|O_NOFOLLOW|O_NOATIME|0xfff8003c)
> = -1 EBADF (Bad file descriptor)
> [pid  5988] write(2, ""..., 41FATAL -> Could not set non-blocking flag
> )         = 41
> [pid  5988] write(2, ""..., 19Bad file descriptor)         = 19
> [pid  5988] write(2, ""..., 1
> )          = 1
> [pid  5988] exit_group(100)             = ?
> Process 5988 detached
> 
> This happened with a kernel after 2.6.24-rc5
> (4af75653031c6d454b4ace47c1536f0d2e727e3e). I rebooted into 2.6.23.8
> and it worked. Now I rebooted into 2.6.24-rc5 again and was able to
> reproduce the failure, so it looks like a kernel issue to me.

With this part of strace output it seems like an obvious userspace bug 
(calling fcntl on a -1 file descriptor). Could be some other change in 
behavior or timing difference is triggering the bug,however.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@...pamshaw.ca
Home Page: http://www.roberthancock.com/

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