Revert "Revert "block, bfq: honor already-setup queue merges""
[ Upstream commit15729ff814
] A crash [1] happened to be triggered in conjunction with commit2d52c58b9c
("block, bfq: honor already-setup queue merges"). The latter was then reverted by commitebc69e897e
("Revert "block, bfq: honor already-setup queue merges""). Yet, the reverted commit was not the one introducing the bug. In fact, it actually triggered a UAF introduced by a different commit, and now fixed by commitd29bd41428
("block, bfq: reset last_bfqq_created on group change"). So, there is no point in keeping commit2d52c58b9c
("block, bfq: honor already-setup queue merges") out. This commit restores it. [1] https://bugzilla.kernel.org/show_bug.cgi?id=214503 Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Link: https://lore.kernel.org/r/20211125181510.15004-1-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Родитель
5b8d69c8c1
Коммит
65d8a73745
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@ -2662,6 +2662,15 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
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* are likely to increase the throughput.
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*/
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bfqq->new_bfqq = new_bfqq;
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/*
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* The above assignment schedules the following redirections:
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* each time some I/O for bfqq arrives, the process that
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* generated that I/O is disassociated from bfqq and
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* associated with new_bfqq. Here we increases new_bfqq->ref
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* in advance, adding the number of processes that are
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* expected to be associated with new_bfqq as they happen to
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* issue I/O.
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*/
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new_bfqq->ref += process_refs;
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return new_bfqq;
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}
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@ -2724,6 +2733,10 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
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{
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struct bfq_queue *in_service_bfqq, *new_bfqq;
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/* if a merge has already been setup, then proceed with that first */
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if (bfqq->new_bfqq)
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return bfqq->new_bfqq;
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/*
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* Check delayed stable merge for rotational or non-queueing
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* devs. For this branch to be executed, bfqq must not be
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@ -2825,9 +2838,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
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if (bfq_too_late_for_merging(bfqq))
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return NULL;
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if (bfqq->new_bfqq)
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return bfqq->new_bfqq;
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if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
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return NULL;
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