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bfq: Update cgroup information before merging bio

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When the process is migrated to a different cgroup (or in case of
writeback just starts submitting bios associated with a different
cgroup) bfq_merge_bio() can operate with stale cgroup information in
bic. Thus the bio can be merged to a request from a different cgroup or
it can result in merging of bfqqs for different cgroups or bfqqs of
already dead cgroups and causing possible use-after-free issues. Fix the
problem by updating cgroup information in bfq_merge_bio().

CC: stable@vger.kernel.org
Fixes: e21b7a0b98 ("block, bfq: add full hierarchical scheduling and cgroups support")
Tested-by: "yukuai (C)" <yukuai3@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220401102752.8599-4-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jan Kara 2022-04-01 12:27:45 +02:00 committed by Jens Axboe
parent 3bc5e683c6
commit ea591cd4eb
1 changed files with 9 additions and 2 deletions
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11
block/bfq-iosched.c
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@ -2457,10 +2457,17 @@ static bool bfq_bio_merge(struct request_queue *q, struct bio *bio,
spin_lock_irq(&bfqd->lock);
if (bic)
if (bic) {
/*
* Make sure cgroup info is uptodate for current process before
* considering the merge.
*/
bfq_bic_update_cgroup(bic, bio);
bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
else
} else {
bfqd->bio_bfqq = NULL;
}
bfqd->bio_bic = bic;
ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);