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authorPaolo Valente <paolo.valente@linaro.org>2020-02-03 11:40:55 +0100
committerJens Axboe <axboe@kernel.dk>2020-02-03 06:58:15 -0700
commit32c59e3a9a5a0b180dd015755d6d18ca31e55935 (patch)
tree1c16f3955e0f71f275c7b62b403e5377b4f0a011 /block
parentf718b093277df582fbf8775548a4f163e664d282 (diff)
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.c4
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