Bug 276080 – sys-kernel/gentoo-sources-2.6.30-r1:pdflush very high CPU usage in KDE4 with root fs on kde4

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Oskar Wrobel 2009-07-01 15:53:27 UTC]

Pdflush gets busy when I had open login on virtual console and from KDE I try to Reboot/Poweroff. There's a window pop-up that asks if I want to terminate active sessions and at the same moment pdflush goes nuts. After that I cannot unmount or sync root partition (ext4), but other partitions(ext4 and reiserfs) seem to be unaffected. Shutting down is "frozen", probably because it's waiting for sync that doesn't occur.

Reproducible: Always

Steps to Reproduce:
1. Start KDE 4 session through KDM
2. Switch to other virtual console,log in and leave opened session there
3. Switch back to KDE and choose shutdown or reboot.
4. When confirmation dialog shows up pdflush will start eating 100% CPU

Actual Results:  
Pdflush causing 100% usage of CPU.

Expected Results:  
Low CPU usage and normal behavior while shutting down.

Shutting down is halted, there are no messages from init. Telinit 0 can help proceed a bit, but only to "next sync", where process stops again. Only way to shutdown system is with "magic SysRq" key.
There was similar bug-report (270805) but it has been closed with CANTFIX due to external patches. I don't use any external patches other than that applied by gentoo-sources patchset. This behavior also occurred with vanilla-sources without any additional patches. I've tested kernels 2.6.28, 2.6.29 and 2.6.30-all behave the same.

emerge --info:
Portage 2.2_rc33 (default/linux/x86/2008.0, gcc-4.4.0, glibc-2.9_p20081201-r2, 2.6.30-gentoo-r1 i686)
=================================================================
System uname: Linux-2.6.30-gentoo-r1-i686-AMD_Athlon-tm-_XP_2200+-with-gentoo-2.0.0
Timestamp of tree: Wed, 01 Jul 2009 05:15:01 +0000
ccache version 2.4 [enabled]
app-shells/bash:     4.0_p17-r1
dev-java/java-config: 2.1.8
dev-lang/python:     2.6.1-r1
dev-util/ccache:     2.4-r8
dev-util/cmake:      2.6.3-r1
sys-apps/baselayout: 2.0.0
sys-apps/openrc:     0.4.3-r2
sys-apps/sandbox:    1.9
sys-devel/autoconf:  2.13, 2.63-r1
sys-devel/automake:  1.5, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10.2
sys-devel/binutils:  2.19.1-r1
sys-devel/gcc-config: 1.4.0-r4
sys-devel/libtool:   2.2.6a
virtual/os-headers:  2.6.28-r1
ACCEPT_KEYWORDS="x86 ~x86"
CBUILD="i686-pc-linux-gnu"
CFLAGS="-march=athlon-xp -O2 -fomit-frame-pointer -pipe"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/4.2/env /usr/kde/4.2/share/config /usr/kde/4.2/shutdown /usr/share/config"
CONFIG_PROTECT_MASK="/etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/splash /etc/terminfo /etc/udev/rules.d"
CXXFLAGS="-march=athlon-xp -O2 -fomit-frame-pointer -pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="ccache distlocks fixpackages parallel-fetch preserve-libs protect-owned sandbox sfperms strict unmerge-orphans userfetch"
GENTOO_MIRRORS="http://ftp.vectranet.pl/gentoo/ http://gentoo.po.opole.pl ftp://mirror.icis.pcz.pl/gentoo/ http://gentoo.inode.at/ http://gd.tuwien.ac.at/opsys/linux/gentoo/ http://trumpetti.atm.tut.fi/gentoo/ http://ftp-stud.fht-esslingen.de/pub/Mirrors/gentoo/ http://ftp.heanet.ie/pub/gentoo/ http://ftp.vectranet.pl/gentoo/ http://gentoo.po.opole.pl ftp://mirror.icis.pcz.pl/gentoo/ "
LANG="en_US.utf8"
LDFLAGS="-Wl,-O1 -Wl,--hash-style=both -Wl,--enable-new-dtags -Wl,--as-needed"
LINGUAS="en pl"
MAKEOPTS="-j1"
PKGDIR="/usr/portage/packages"
PORTAGE_CONFIGROOT="/"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/mnt/hdb6/src"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/portage/layman/sunrise /usr/local/portage/layman/kde-testing /usr/local/portage/layman/roslin /root/overlay"
SYNC="rsync://rsync.europe.gentoo.org/gentoo-portage"
USE="3dnow 3dnowext 7zip S3TC X a52 aac aalib acl acpi aften agg alsa amarok amarok2 archive arts aspell audiofile audioscrobbler bash-completion berkdb bzip2 cairo calendar ccache cddb cdinstall cdr cdrkit cdrom cdrtools cg chardet chm cli cmake connectionstatus cracklib crypt css ctype cups cupsddk curl curlwrappers cvs cxx dbus dia dialup divx djvu dnotify doc dot downloadorder dragonplayer dri dvd dvdnav dvdr ebook editor eigen emerald emoticon excel exif extraicons extramodules fam fat fbcon fbcondecor fbdev fbsplash ffmpeg fftw firefox flac floppy fltk fontconfig fortran fortune ftp fuse gadu gdbm gecko gif git glib glitz gmail gmp gnokii google google-gadgets gpm graphite graphviz grub gs gstreamer gtk gtkstyle hal highlight ical iconv icq icu id3 id3tag imagemagick imlib inkjar inotify ipv6 irc isdnlog jabber jack java javascript jpeg jpeg2k kate kcal kde kde4 kdepim kig-scripting kipi kontact kqemu lame lcms libnotify libsexy lm_sensors logrotate logviewer lvm lyrics lyrics-screen lzma lzo mad mediaplayer mercurial metric midi mime mmx mmxext mng moc mods mouse mp3 mp4 mpeg mpeg2 mplayer mudflap musicbrainz ncurses net network nls normalize nptl nptlonly nsplugin ntfs nvidia offensive ogg ogg123 ogm ole openal opengl openmp oxygen pam pch pcre pdf perl plasma plotutils png poppler-data postproc powerkadu ppds pppd privacy ps pulseaudio python qmake qmax qt3 qt3support qt4 rar readline realmedia recode redeyes redland reflection reiser4 reiserfs replaygain resid rpm rss ruby scanner schroedinger scrobbler sdl search semantic-desktop sensord session shaders sharedmem shout skins slit sndfile solver spell spl sqlite sse ssl startup-notification stream stroke subtitles subversion suid svg svgz sysfs systray t1lib taglib tagwriting tcpd teamarena templates theora threads threadsafe thumbnail tiff trayicon tremor truetype tunepimp twisted twolame ui unicode unsupported vcd vcdinfo vcdx visualization vlc vorbis vorbis-psy webkit win32codecs wma wmf wmp wordexp wxwindows x264 x86 xattr xcomposite xine xorg xorgmodule xosd xrandr xrender xslt xv xvid xvmc zip zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1 emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" ELIBC="glibc" INPUT_DEVICES="keyboard mouse evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="en pl" USERLAND="GNU" VIDEO_CARDS="nvidia vesa"
Unset:  CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, FFLAGS, INSTALL_MASK, LC_ALL, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS

[Comment 1 Oskar Wrobel 2009-07-01 15:59:34 UTC]

Created attachment 196257 [details]
.config from gentoo-sources-2.6.30-r1

[Comment 2 Robin Johnson 2009-07-04 22:46:37 UTC]

Comment on attachment 196257 [details]
.config from gentoo-sources-2.6.30-r1

Please use the correct MIME types for attachments.

[Comment 3 Mike Pagano 2009-07-08 23:51:54 UTC]

were all the kernels tested compiled with gcc 4.4.0 ?

[Comment 4 Oskar Wrobel 2009-07-10 05:43:38 UTC]

Yes, they all were compiled with gcc-4.4.0. Also 2.6.28 compiled with gcc-4.3.3 had this bug, I decided to switch to gcc-4.4.0 because of this.

[Comment 5 Stratos Psomadakis (RETIRED) 2009-07-27 00:22:41 UTC]

http://bugzilla.kernel.org/show_bug.cgi?id=13583
seems to be related to this bug

[Comment 6 Oskar Wrobel 2009-07-28 09:19:57 UTC]

I've just find out that running oprofiled together with any io-intensive application (such as emerge) guarantees high pdflush cpu-usage after couple of seconds. So this problem is not KDE4 specific. Unfortunately this means that I'm unable to get longer oprofile traces without triggering the bug.
I will attach logs from oprofile, one from idle system and the other with cpu-intensive pdflush. They were collected from 2.6.30-tuxonice-r4 compiled with gcc-4.4.1.

[Comment 7 Oskar Wrobel 2009-07-28 09:20:58 UTC]

Created attachment 199422 [details]
Oprofile log from idle system

[Comment 8 Oskar Wrobel 2009-07-28 09:22:27 UTC]

Created attachment 199423 [details]
Oprofile log with pdflush bug triggered

[Comment 9 Stratos Psomadakis (RETIRED) 2009-07-29 16:13:54 UTC]

i see some patches in 2.6.31-rc[12], and some activity at lkml about oprofile, so you can try an -rc kernel, just in case

[Comment 10 Oskar Wrobel 2009-08-16 18:33:03 UTC]

Looks like it's fixed in 2.6.31-rc5. Thanks.

[Comment 11 Mike Pagano 2009-08-16 23:11:21 UTC]

This is good news. Let's keep this open and see if we can identify the fix for backport to 2.6.30 or until 2.6.31 get's into the tree

[Comment 12 Mike Pagano 2009-09-10 13:19:05 UTC]

gentoo-sources-2.6.31 released