From: Tejun Heo <t...@kernel.org> 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 <t...@kernel.org> Acked-by: Jeff Moyer <jmo...@redhat.com> Cc: Vivek Goyal <vgo...@redhat.com> Cc: Arianna Avanzini <avanzini.aria...@gmail.com> Signed-off-by: Jens Axboe <ax...@fb.com> https://jira.sw.ru/browse/PSBM-41334 (cherry picked from commit 95e5d6f62693f27d9011ec307eb32c6126314ea3) Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.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 a4149c3..911baae 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3711,7 +3711,7 @@ 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; } -- 2.4.10 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
