On Tue, Jul 30, 2019 at 11:17:57AM -0700, Bart Van Assche wrote: > generic_make_request_checks() needs to be protected by a > blk_queue_enter() / blk_queue_exit() pair because it calls > blkcg_bio_issue_check() and because that last function calls > blkg_lookup(). > > This patch fixes https://syzkaller.appspot.com/bug?id=ff9ab4a23afa7553fb79f745a92be87ba4144508. > > This patch also fixes the following kernel warning, triggered by > blktests: > > WARNING: CPU: 5 PID: 10706 at block/blk-core.c:903 generic_make_request_checks+0x9c6/0xe60 > RIP: 0010:generic_make_request_checks+0x9c6/0xe60 > Call Trace: > generic_make_request+0x7a/0x5c0 > submit_bio+0x92/0x280 > mpage_readpages+0x2b1/0x300 > blkdev_readpages+0x1d/0x20 > read_pages+0xd9/0x2c0 > __do_page_cache_readahead+0x2e0/0x310 > force_page_cache_readahead+0xfb/0x170 > page_cache_sync_readahead+0x28d/0x2a0 > generic_file_read_iter+0xc13/0x1530 > blkdev_read_iter+0x7d/0x90 > new_sync_read+0x2c5/0x3d0 > __vfs_read+0x7b/0x90 > vfs_read+0xc6/0x1f0 > ksys_read+0xc3/0x160 > __x64_sys_read+0x43/0x50 > do_syscall_64+0x71/0x270 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Ming Lei <ming.lei@xxxxxxxxxx> > Cc: Hannes Reinecke <hare@xxxxxxxx> > Cc: Johannes Thumshirn <jthumshirn@xxxxxxx> > Cc: Alexandru Moise <00moses.alexander00@xxxxxxxxx> > Cc: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> > Reported-by: syzbot+ff9ab4a23afa7553@xxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> > --- > block/blk-core.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index ff27c3080348..cd844c54e9f1 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -1150,6 +1150,9 @@ EXPORT_SYMBOL_GPL(direct_make_request); > */ > blk_qc_t submit_bio(struct bio *bio) > { > + struct request_queue *q = bio->bi_disk->queue; > + blk_qc_t ret; > + > if (blkcg_punt_bio_submit(bio)) > return BLK_QC_T_NONE; > > @@ -1182,7 +1185,15 @@ blk_qc_t submit_bio(struct bio *bio) > } > } > > - return generic_make_request(bio); > + if (unlikely(blk_queue_enter(q, 0) < 0)) { > + bio->bi_status = BLK_STS_IOERR; > + bio->bi_end_io(bio); > + return BLK_QC_T_NONE; > + } > + ret = generic_make_request(bio); > + blk_queue_exit(q); No, nested blk_queue_enter() is easy to cause deadlock. Thanks, Ming
