http://bugzilla.novell.com/show_bug.cgi?id=581585 http://bugzilla.novell.com/show_bug.cgi?id=581585#c0 Summary: plasma desktop (KDE4) freezes during the free cluster scan on vfat removable partitions Classification: openSUSE Product: openSUSE 11.2 Version: Final Platform: i586 OS/Version: openSUSE 11.2 Status: NEW Severity: Normal Priority: P5 - None Component: KDE4 Workspace AssignedTo: kde-maintainers@suse.de ReportedBy: rfb@ch-open.ch QAContact: qa@suse.de Found By: --- Blocker: --- User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.7) Gecko/20091222 SUSE/3.5.7-1.1.1 Firefox/3.5.7 Unless a removable device with a vfat file system is mounted with the "usefree" option the system performs a scan of the whole vfat filesystem to determine the actual free cluster value immediately after the actual mounting of the device. This is done, because Windows might not update the value correctly. By using the "usefree" option the scan is not performed and the free cluster value from the file systems meta data is trusted. During the scan, which is done by default, the KDE4 desktop (panel and "click activity" on the background) freeze. The applications work normal if by change they have the focus. Also, the window manager allows to change focus between the applications on a given virtual desktop, but switching to another desktop is typically not possible, because all panel activity is blocked. The freeze doesn't start immediately at the moment the mount is performed and the free cluster scanning is started. There is some kind of "buildup" (see below). If then the freeze sets in and by coincidance a desktop component like the device notifier panel or the background context menu is up, which grabs the focus completely, the freeze is total an lasts until the disk scanning is over. There are strong indications, that the phenomenon has to do with the kernel based filesystem event notification mechanism (inotify). It seems that the scanning of the vfat partition generates an event storm which after a few seconds floods KDEs event handling system completely, which then leads to the starvation of the corresponding mouse events. It is not clear whether the problem is that KDE4 is not protecting itself enough against event flooding or whether the vfat scanning is violating principles with respect to inotify. All attemps to produce equally bad event storms with various forms of filesystem activities on ext3 and ext4 filesystems have failed and it looks as if the bad behavior might be attributed to the vfat software. The problem can easily be reproduced. All it takes is a removable vfat device with enough data on it such that the partition scan lasts long enough. The problem is avoided by mounting the partition with "-o usefree". One solution is to mount the device by hand. Because mount options for removable devices when mounted through the device notifier cannot be set by configuration means anymore in the installation in question, a workaround is attached, such that a vfat device again can be mounted in the usual comfortable way but with the usefree option set. It consist of replacing /usr/lib/hal/hal-storage-mount (which is called by hald upon mounting) by a bash scripts wich adds the usefree option when the binary hal-storage-mount is called. The phenomen has been observed by other users, too as discussed in a german forum: http://www.linuxforen.de/forums/showthread.php?p=1740911#post1740911 At least one of the users has applied the workaround successfully. Probably many users know about the phenomenon but can live with it, because the freeze only takes a few seconds. On the other hand, on vfat devices with several hundred directories and files, freezes that last more than a minute have been observed. The behavior was present in opensuse 11.1, too. Reproducible: Always Steps to Reproduce: Assuming the vfat usb disk (or stick) with enough data gets /dev/sdb1 assigned, do this: mount -t vfat -o usefree /dev/sdb1 /mnt umount /mnt mount -t vfat /dev/sdb1 /mnt umount /mnt . . . After each mount change to a different virtual desktop once every second. Actual Results: Each time the device is mounted without -o usefree, the destop switching gets blocked until the disk scan is over. To find out how long the disk scan lasts, keep the focus on the shell you issue the mount command and do the umount immediately. The filesystem will be "busy" as long as the scan takes place. By the way, the device is accessible for reading during the scanning. Expected Results: The desktop switching should not be hindered by the disk scan. The desktop switching stands for any mouse activities involving the plasma desktop, especially the panel, but not mouse events which belong to the applications or the window manager. -- Configure bugmail: http://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.