On (05/07/15 16:41), Minchan Kim wrote: > > Unfortunately, I can reproduce in a few second with this patch. >
so I googled a bit, and it seems that zram is not the only one who suffered from add_disk() behaviour. http://www.spinics.net/lists/dm-devel/msg23465.html and there is http://git.kernel.dk/?p=linux-block.git;a=commitdiff;h=6cd18e71;hp=393a33970540ac6a2c894b0d6ef3f5d485860884 that looks interesting: | | Because of the peculiar way that md devices are created (automatically | when the device node is opened), a new device can be created and | registered immediately after the | blk_unregister_region(disk_devt(disk), disk->minors); | call in del_gendisk(). | | Therefore it is important that all visible artifacts of the previous | device are removed before this call. In particular, the 'bdi'. | basically, it destroys bdi during queue cleanup. > moved the > device_unregister(bdi->dev); > call from bdi_unregister() to bdi_destroy() it has been quite easy to > lose a race and have a new (e.g.) "md127" be created after the > blk_unregister_region() call and before bdi_destroy() is ultimately > called by the final 'put_disk', which must come after del_gendisk(). > > The new device finds that the bdi name is already registered in sysfs > and complains > >> [ 9627.630029] WARNING: CPU: 18 PID: 3330 at fs/sysfs/dir.c:31 >> sysfs_warn_dup+0x5a/0x70() >> [ 9627.630032] sysfs: cannot create duplicate filename >> '/devices/virtual/bdi/9:127' > > We can fix this by moving the bdi_destroy() call out of > blk_release_queue() (which can happen very late when a refcount > reaches zero) and into blk_cleanup_queue() - which happens exactly when the md > device driver calls it. that does look like something that can happen in our case. and here: http://www.spinics.net/lists/dm-devel/msg23415.html is there any chance to ask you to test with these patches (no rush, take your time)? as I'm still unable to reproduce it locally. -ss -- 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/
