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| author | Paolo Valente <paolo.valente@linaro.org> | 2021-11-25 19:15:10 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-15 14:14:54 +0200 |
| commit | f990f0985eda59d4f29fc83fcf300c92b1225d39 (patch) | |
| tree | c61f01ec1a631c2e414a4ce7f1da494b3b23a804 /block | |
| parent | 36b6b62b69d1ccb8a3074dd6a3e9a1a79fbd3fcc (diff) | |
| download | linux-f990f0985eda59d4f29fc83fcf300c92b1225d39.tar.gz linux-f990f0985eda59d4f29fc83fcf300c92b1225d39.tar.bz2 linux-f990f0985eda59d4f29fc83fcf300c92b1225d39.zip | |
Revert "Revert "block, bfq: honor already-setup queue merges""
[ Upstream commit 15729ff8143f8135b03988a100a19e66d7cb7ecd ]
A crash [1] happened to be triggered in conjunction with commit
2d52c58b9c9b ("block, bfq: honor already-setup queue merges"). The
latter was then reverted by commit ebc69e897e17 ("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 commit d29bd41428cf
("block, bfq: reset last_bfqq_created on group change").
So, there is no point in keeping commit 2d52c58b9c9b ("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>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index dfd55037dc6f..a9f42df92ea3 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2155,6 +2155,15 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) * are likely to increase the throughput. */ bfqq->new_bfqq = new_bfqq; + /* + * The above assignment schedules the following redirections: + * each time some I/O for bfqq arrives, the process that + * generated that I/O is disassociated from bfqq and + * associated with new_bfqq. Here we increases new_bfqq->ref + * in advance, adding the number of processes that are + * expected to be associated with new_bfqq as they happen to + * issue I/O. + */ new_bfqq->ref += process_refs; return new_bfqq; } @@ -2214,6 +2223,10 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, { struct bfq_queue *in_service_bfqq, *new_bfqq; + /* if a merge has already been setup, then proceed with that first */ + if (bfqq->new_bfqq) + return bfqq->new_bfqq; + /* * Prevent bfqq from being merged if it has been created too * long ago. The idea is that true cooperating processes, and @@ -2228,9 +2241,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (bfq_too_late_for_merging(bfqq)) return NULL; - if (bfqq->new_bfqq) - return bfqq->new_bfqq; - if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) return NULL; |