On Mon, Mar 9, 2015 at 12:30 AM, NeilBrown <ne...@suse.de> wrote: > On Sun, 08 Mar 2015 18:14:39 +0100 Prakash Punnoor <prak...@punnoor.de> wrote: > >> Hi, >> >> I noticed the udisks daemon (version 2.1.4) suddenly started using high >> cpu (one core at 100%) with linux 4.0 git kernel. I bisected it to: >> >> 750f199ee8b578062341e6ddfe36c59ac8ff2dcb
I had the same problem upgrading from 4.0-rc1 to 4.0-rc3. I have just finished bisecting and "fixing" it. My bisect points to the same commit. Looking at udisksd with strace sees a loop of polling and then accessing several md related sysfs files. The only file that udisksd monitors and was changes by that commit was "sync_action". If I revert this part of the commit, my system works normal again: static struct md_sysfs_entry md_scan_mode = - __ATTR_PREALLOC(sync_action, S_IRUGO|S_IWUSR, action_show, action_store); + __ATTR(sync_action, S_IRUGO|S_IWUSR, action_show, action_store); It seems that polling is broken for peralloc files. The cause seems to be that kernfs_seq_show() updates ->event, while the new sysfs_kf_read() does not. So the polling will always trigger and udisksd goes into an inifinite loop looking for changes that are not there. I fixed my local system by copying the line "of->event = atomic_read(&of->kn->attr.open->event);" from kernfs_seq_show() into sysfs_kf_read(). (I also needed to move the definition of struct kernfs_open_node from kernfs/file.c to kefs-internal.h) udisksd now again behaves normal, but I'm not sending this change as a patch, because I do not know about the locking and livetime of these objects to evaluate, if that is really the correct fix. Thanks, Torsten -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/