For loop, the root cause is one ABBA and one AA lock dependency issue, and the two are fixed by patch 2 and patch 3 each.
Another reason is from the trylock in blkdev_reread_part(), which may cause partition scanning failure too sometimes when another task is holding the bd_mutex. In the discussion[1], both Tejun and Christoph suggests to replace the trylock with mutex_lock in blkdev_reread_part(), also Christoph suggests to export blkdev_reread_part. Following the discussion, this patchset exports blkdev_reread_part(), and introduces lockless __blkdev_reread_part() for fixing loop's AA lock issue. Then ioctl_by_bdev(BLKRRPART) in loop, nbd and dasd is replaced with blkdev_reread_part(). In the last patch, trylock in blkdev_reread_part() is replaced with mutex_lock, and some analysis is provided about the conversion. This is a slightly reworked set from what Ming sent a few days ago, based on Christoph's feedback. I've tested this out quite succesfully in the scenario that prompted my first patch as well. [1], https://lkml.org/lkml/2015/1/26/137 [2], https://lkml.org/lkml/2015/3/31/888 Jarod Wilson (3): block: export blkdev_reread_part() and __blkdev_reread_part() block: loop: fix another reread part failure s390/block/dasd: remove obsolete while -EBUSY loop Ming Lei (4): block: loop: don't hold lo_ctl_mutex in lo_open block: nbd: convert to blkdev_reread_part() block: dasd_genhd: convert to blkdev_reread_part block: replace trylock with mutex_lock in blkdev_reread_part() block/ioctl.c | 34 +++++++++++++++++++---- drivers/block/loop.c | 60 ++++++++++++++++++++++++++++++++++------- drivers/block/loop.h | 1 + drivers/block/nbd.c | 2 +- drivers/s390/block/dasd_genhd.c | 22 +++++---------- include/linux/fs.h | 3 +++ 6 files changed, 90 insertions(+), 32 deletions(-) CC: Christoph Hellwig <h...@infradead.org> CC: Jens Axboe <ax...@kernel.dk> CC: Tejun Heo <t...@kernel.org> CC: Alexander Viro <v...@zeniv.linux.org.uk> CC: Markus Pargmann <m...@pengutronix.de> CC: Stefan Weinhuber <w...@de.ibm.com> CC: Stefan Haberland <stefan.haberl...@de.ibm.com> CC: Sebastian Ott <seb...@linux.vnet.ibm.com> CC: Fabian Frederick <f...@skynet.be> CC: Ming Lei <ming....@canonical.com> CC: David Herrmann <dh.herrm...@gmail.com> CC: Mike Galbraith <bitbuc...@online.de> CC: Andrew Morton <a...@linux-foundation.org> CC: Peter Zijlstra <pet...@infradead.org> CC: nbd-gene...@lists.sourceforge.net CC: linux-s...@vger.kernel.org -- 1.8.3.1 -- 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/
