On Fri, Oct 09 2015 at 3:52pm -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > Turns out that this change: > http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/commit/?h=wip&id=2639638c77768a86216be456c2764e32a2bcd841 > > needed to be reverted with: > http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/commit/?h=wip&id=ad3ccd760da7c05b90775372f9b39dc2964086fe > > Because nested plugs caused generic_make_request()'s onstack bio_list to > go out of scope (blk_finish_plug() wouldn't actually flush the list > within generic_make_request because XFS already added an outermost > plug). > > But even after fixing that I then hit issues with these changes now > resulting in imperfect 'in_generic_make_request' accounting that happens > lazily once the outermost plug completes blk_finish_plug. manifested as > dm-bufio.c:dm_bufio_prefetch's BUG_ON(dm_bufio_in_request()); hitting. > > Basically using the blk-core's onstack plugging isn't workable for > fixing this deadlock and we're back to having to seriously consider > this (with its additional hook in the scheduler): http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/commit/?h=wip&id=a91709cd32b5ca7ca047b68c9299e747f2ae6ca2 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
