diff options
authorBart Van Assche <>2017-04-21 12:00:40 -0600
committerJens Axboe <>2017-04-21 12:00:40 -0600
commitabc25a693091e61537e40dfe24e8ee5deaf08208 (patch)
parentf8a05a1d01d9bb8aba78339d1e4b559e5db3b716 (diff)
blk-mq: Fix preempt count imbalance
Avoid that the following kernel bug gets triggered: BUG: sleeping function called from invalid context at ./include/linux/buffer_head.h:349 in_atomic(): 1, irqs_disabled(): 0, pid: 8019, name: find CPU: 10 PID: 8019 Comm: find Tainted: G W I 4.11.0-rc4-dbg+ #2 Call Trace: dump_stack+0x68/0x93 ___might_sleep+0x16e/0x230 __might_sleep+0x4a/0x80 __ext4_get_inode_loc+0x1e0/0x4e0 ext4_iget+0x70/0xbc0 ext4_iget_normal+0x2f/0x40 ext4_lookup+0xb6/0x1f0 lookup_slow+0x104/0x1e0 walk_component+0x19a/0x330 path_lookupat+0x4b/0x100 filename_lookup+0x9a/0x110 user_path_at_empty+0x36/0x40 vfs_statx+0x67/0xc0 SYSC_newfstatat+0x20/0x40 SyS_newfstatat+0xe/0x10 entry_SYSCALL_64_fastpath+0x18/0xad This happens since the big if/else in blk_mq_make_request() doesn't have final else section that also drops the ctx. Add that. Fixes: b00c53e8f411 ("blk-mq: fix schedule-while-atomic with scheduler attached") Signed-off-by: Bart Van Assche <> Cc: Omar Sandoval <> Added a bit more to the commit log. Signed-off-by: Jens Axboe <>
1 files changed, 2 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0b2f60407748..e6aad49c1686 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1639,7 +1639,8 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
} else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
blk_mq_run_hw_queue(data.hctx, true);
- }
+ } else
+ blk_mq_put_ctx(data.ctx);
return cookie;