On Sun, 7 Feb 2010, Hugh Dickins wrote: > > This message has been generated automatically as a part of a summary report > > of recent regressions. > > > > The following bug entry is on the current list of known regressions > > from 2.6.32. Please verify if it still should be listed and let the > > tracking team > > know (either way). > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=15202 > > Subject : lockdep warning during elevator_switch > > Submitter : Hugh Dickins <[email protected]> > > Date : 2010-01-31 23:55 (8 days old) > > References : http://marc.info/?l=linux-kernel&m=126498212613051&w=4 > > Yes, still so in 2.6.33-rc7. >
This type of lock dependency is always going to exist whenever a write to a sysfs file causes the kernel to remove its dirent. In this case, writing to /sys/devices/block/xxx/queue/scheduler takes sd->dep_map and sd->parent->dep_map via sysfs_get_active_two() to pin both via sysfs_write_file(). The call to kobject_del() removes its directory from the hierarchy which takes sd->dep_map in sysfs_deactivate() because of 846f99749a. Eric, do we need to preempt the rwsem from being acquired here when the dirent is already pinned because of a store to one of its files? -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
