diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2025-06-26 19:57:43 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2025-06-26 07:34:11 -0600 |
| commit | c007062188d8e402c294117db53a24b2bed2b83f (patch) | |
| tree | 7473021b3beaaf24cbc2c5fb5b562e8ad6a668b0 | |
| parent | 5990b776fb79a444f91431d35d24b0bdc622984b (diff) | |
block: fix false warning in bdev_count_inflight_rw()
While bdev_count_inflight is interating all cpus, if some IOs are issued
from traversed cpu and then completed from the cpu that is not traversed
yet:
cpu0
cpu1
bdev_count_inflight
//for_each_possible_cpu
// cpu0 is 0
infliht += 0
// issue a io
blk_account_io_start
// cpu0 inflight ++
cpu2
// the io is done
blk_account_io_done
// cpu2 inflight --
// cpu 1 is 0
inflight += 0
// cpu2 is -1
inflight += -1
...
In this case, the total inflight will be -1, causing lots of false
warning. Fix the problem by removing the warning.
Noted there is still a valid warning for nvme-mpath(From Yi) that is not
fixed yet.
Fixes: f5482ee5edb9 ("block: WARN if bdev inflight counter is negative")
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Closes: https://lore.kernel.org/linux-block/aFtUXy-lct0WxY2w@mozart.vkv.me/T/#mae89155a5006463d0a21a4a2c35ae0034b26a339
Reported-and-tested-by: Calvin Owens <calvin@wbinvd.org>
Closes: https://lore.kernel.org/linux-block/aFtUXy-lct0WxY2w@mozart.vkv.me/T/#m1d935a00070bf95055d0ac84e6075158b08acaef
Reported-by: Dave Chinner <david@fromorbit.com>
Closes: https://lore.kernel.org/linux-block/aFuypjqCXo9-5_En@dread.disaster.area/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250626115743.1641443-1-yukuai3@huawei.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/genhd.c | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/block/genhd.c b/block/genhd.c index 8171a6bc3210..c26733f6324b 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -128,23 +128,27 @@ static void part_stat_read_all(struct block_device *part, static void bdev_count_inflight_rw(struct block_device *part, unsigned int inflight[2], bool mq_driver) { + int write = 0; + int read = 0; int cpu; if (mq_driver) { blk_mq_in_driver_rw(part, inflight); - } else { - for_each_possible_cpu(cpu) { - inflight[READ] += part_stat_local_read_cpu( - part, in_flight[READ], cpu); - inflight[WRITE] += part_stat_local_read_cpu( - part, in_flight[WRITE], cpu); - } + return; + } + + for_each_possible_cpu(cpu) { + read += part_stat_local_read_cpu(part, in_flight[READ], cpu); + write += part_stat_local_read_cpu(part, in_flight[WRITE], cpu); } - if (WARN_ON_ONCE((int)inflight[READ] < 0)) - inflight[READ] = 0; - if (WARN_ON_ONCE((int)inflight[WRITE] < 0)) - inflight[WRITE] = 0; + /* + * While iterating all CPUs, some IOs may be issued from a CPU already + * traversed and complete on a CPU that has not yet been traversed, + * causing the inflight number to be negative. + */ + inflight[READ] = read > 0 ? read : 0; + inflight[WRITE] = write > 0 ? write : 0; } /** |