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| author |   Paolo Valente <paolo.valente@linaro.org> | 2020-02-03 11:40:55 +0100 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2020-02-03 06:58:15 -0700 |
| commit | 32c59e3a9a5a0b180dd015755d6d18ca31e55935 (patch) | |
| tree | 1c16f3955e0f71f275c7b62b403e5377b4f0a011 /block | |
| parent | block, bfq: do not plug I/O for bfq_queues with no proc refs (diff) | |
| download | wireguard-linux-32c59e3a9a5a0b180dd015755d6d18ca31e55935.tar.xz wireguard-linux-32c59e3a9a5a0b180dd015755d6d18ca31e55935.zip | |
block, bfq: do not insert oom queue into position tree
BFQ maintains an ordered list, implemented with an RB tree, of
head-request positions of non-empty bfq_queues. This position tree,
inherited from CFQ, is used to find bfq_queues that contain I/O close
to each other. BFQ merges these bfq_queues into a single shared queue,
if this boosts throughput on the device at hand.
There is however a special-purpose bfq_queue that does not participate
in queue merging, the oom bfq_queue. Yet, also this bfq_queue could be
wrongly added to the position tree. So bfqq_find_close() could return
the oom bfq_queue, which is a source of further troubles in an
out-of-memory situation. This commit prevents the oom bfq_queue from
being inserted into the position tree.
Tested-by: Patrick Dung <patdung100@gmail.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 55d4328e7c12..15dfb0844644 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -613,6 +613,10 @@ bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) bfqq->pos_root = NULL; } + /* oom_bfqq does not participate in queue merging */ + if (bfqq == &bfqd->oom_bfqq) + return; + /* * bfqq cannot be merged any longer (see comments in * bfq_setup_cooperator): no point in adding bfqq into the |