Bugzilla Bug 156493

In its default configuration procmail will try to use all available
locking mechanisms, all at once: dot-locking, fcntl, lockf (basically
the same thing as fcntl) and flock. Unfortunately starting with the
2.6.17 kernels the fcntl and flock locking mechanisms do not work well
together over NFS. When an NFS file is locked with
fcntl(fd,F_SETLK,...) a subsequent flock() operation on the file will
fail.

The result is that procmail forever loops on the failing locks. 

To reproduce:

1. Use a 2.6.17 or 2.6.18 kernel
2. Put the following in test.rc:

:0: 
$HOME/testfolder

Replace $HOME with a directory that is located on NFS

3. Run the following command:
echo|procmail test.rc

Use strace to see the failing flock() system call:
fcntl64(7, F_SETLKW, {type=F_WRLCK, whence=SEEK_SET, start=0, len=0}) = 0
fcntl64(7, F_SETLK, {type=F_WRLCK, whence=SEEK_CUR, start=0, len=0}) = 0
flock(7, LOCK_EX|LOCK_NB)               = -1 EAGAIN (Resource temporarily
unavailable)

The following patch disables flock style locking:

--- procmail-3.22-r8.ebuild.orig        2006-10-07 18:06:20.000000000 -0700
+++ procmail-3.22-r8.ebuild     2006-11-28 01:59:22.000000000 -0800
@@ -28,6 +28,12 @@
                -e "s:#LOCKINGTEST=/tmp:LOCKINGTEST=/tmp:" \
                -i Makefile

+       # disable flock, using both fcntl and flock style locking
+       # doesn't work with NFS with 2.6.17+ kernels
+
+       sed -e "s:/\*#define NO_flock_LOCK:#define NO_flock_LOCK:" \
+               -i config.h
+
        if ! use mbox ; then
                echo "# Use maildir-style mailbox in user's home directory" >
${S}/procmailrc
                echo 'DEFAULT=$HOME/.maildir/' >> ${S}/procmailrc

For what its worth, at least one other major distribution has been
shipping with a similar patch for many years.

Portage 2.1.1-r1 (default-linux/x86/2006.0, gcc-3.4.4, glibc-2.3.5-r2, 2.6.17.4
i686)
=================================================================
System uname: 2.6.17.4 i686 AMD Athlon(tm) 64 Processor 3200+
Gentoo Base System version 1.6.15
Last Sync: Tue, 21 Nov 2006 05:20:01 +0000
ccache version 2.3 [disabled]
app-admin/eselect-compiler: [Not Present]
dev-java/java-config: 1.3.7, 2.0.30
dev-lang/python:     2.4.2
dev-python/pycrypto: 2.0.1-r5
dev-util/ccache:     2.3
dev-util/confcache:  [Not Present]
sys-apps/sandbox:    1.2.12
sys-devel/autoconf:  2.13, 2.59-r6
sys-devel/automake:  1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r1
sys-devel/binutils:  2.16.1-r3
sys-devel/gcc-config: 1.3.12-r6
sys-devel/libtool:   1.5.22
virtual/os-headers:  2.6.11-r2
ACCEPT_KEYWORDS="x86"
AUTOCLEAN="yes"
CBUILD="i686-pc-linux-gnu"
CFLAGS="-march=athlon-xp -O2 -pipe -fomit-frame-pointer"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/3.5/env /usr/kde/3.5/share/config
/usr/kde/3.5/shutdown /usr/lib/mozilla/defaults/pref /usr/share/X11/xkb
/usr/share/config /usr/share/texmf/dvipdfm/config/
/usr/share/texmf/dvips/config/ /usr/share/texmf/tex/generic/config/
/usr/share/texmf/tex/platex/config/ /usr/share/texmf/xdvi/"
CONFIG_PROTECT_MASK="/etc/env.d /etc/env.d/java/ /etc/gconf
/etc/java-config/vms/ /etc/revdep-rebuild /etc/terminfo"
CXXFLAGS="-march=athlon-xp -O2 -pipe -fomit-frame-pointer"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoconfig distlocks metadata-transfer nostrip notitles
parallel-fetch sandbox sfperms strict"
GENTOO_MIRRORS="http://gentoo.oregonstate.edu
http://www.ibiblio.org/pub/Linux/distributions/gentoo"
MAKEOPTS="-j2"
PKGDIR="/usr/portage/packages"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress
--force --whole-file --delete --delete-after --stats --timeout=180
--exclude='/distfiles' --exclude='/local' --exclude='/packages'"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
SYNC="rsync://rsync.us.gentoo.org/gentoo-portage"
USE="x86 3dnow X a52 aac alsa apache2 apm asf berkdb bitmap-fonts cli cracklib
crypt cups dlloader doc dri dvd dvdread eds elibc_glibc emacs emboss encode
ffmpeg flac foomaticdb fortran gdbm gif gstreamer gtk gtk2 iconv imlib
input_devices_evdev input_devices_keyboard input_devices_mouse isdnlog
javascript joystick jpeg kernel_linux libg++ libwww mad mailwrapper mikmod mmx
mp3 mpeg ncurses nls nptl nvidia ogg opengl oss pam pcre perl png pppd python
qt3 qt4 quicktime readline reflection sdl session spell spl ssl tcpd theora
threads tiff truetype truetype-fonts type1-fonts udev userland_GNU
video_cards_apm video_cards_ark video_cards_ati video_cards_chips
video_cards_cirrus video_cards_cyrix video_cards_dummy video_cards_fbdev
video_cards_glint video_cards_i128 video_cards_i740 video_cards_i810
video_cards_imstt video_cards_mga video_cards_neomagic video_cards_nsc
video_cards_nv video_cards_rendition video_cards_s3 video_cards_s3virge
video_cards_savage video_cards_siliconmotion video_cards_sis video_cards_sisusb
video_cards_tdfx video_cards_tga video_cards_trident video_cards_tseng
video_cards_v4l video_cards_vesa video_cards_vga video_cards_via
video_cards_vmware video_cards_voodoo vorbis win32codecs xml xorg xv zlib"
Unset:  CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LANG, LC_ALL, LDFLAGS,
LINGUAS, PORTAGE_RSYNC_EXTRA_OPTS, PORTDIR_OVERLAY

This is fixed in procmail-3.22-r9.