Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 2/8] cfq-iosched: fix async oom queue handling | Date | Mon, 8 Jun 2015 17:59:27 +0900 |
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Async cfqq's (cfq_queue's) are shared across cfq_data. When cfq_get_queue() obtains a new queue from cfq_find_alloc_queue(), it stashes the pointer in cfq_data and reuses it from then on; however, the function doesn't consider that cfq_find_alloc_queue() may return the oom_cfqq under memory pressure and installs the returned queue unconditionally.
If the oom_cfqq is installed as an async cfqq, cfq_set_request() will continue calling cfq_get_queue() hoping to replace it with a proper queue; however, cfq_get_queue() will keep returning the cached queue for the slot - the oom_cfqq.
Fix it by skipping caching if the queue is the oom one.
Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> --- block/cfq-iosched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 2814bb7..c7b33aa 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3683,7 +3683,7 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic, /* * pin the queue now that it's allocated, scheduler exit will prune it */ - if (!is_sync) { + if (!is_sync && cfqq != &cfqd->oom_cfqq) { cfqq->ref++; *async_cfqq = cfqq; } -- 2.4.2
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