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authorTejun Heo <tj@kernel.org>2015-08-19 00:54:59 +0300
committerJens Axboe <axboe@fb.com>2015-08-19 01:49:16 +0300
commitbce6133b09013f70d41a678d262a12147ed43889 (patch)
tree58cea8112fb0e35d94ff30f9d30184c7b424d66f /block
parent95e5d6f62693f27d9011ec307eb32c6126314ea3 (diff)
downloadlinux-bce6133b09013f70d41a678d262a12147ed43889.tar.xz
cfq-iosched: fix oom cfq_queue ref leak in cfq_set_request()
If the cfq_queue cached in cfq_io_cq is the oom one, cfq_set_request() replaces it by invoking cfq_get_queue() again without putting the oom queue leaking the reference it was holding. While oom queues are not released through reference counting, they're still reference counted and this can theoretically lead to the reference count overflowing and incorrectly invoke the usual release path on it. Fix it by making cfq_set_request() put the ref it was holding. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Jeff Moyer <jmoyer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index baf0b706169d..8acfb7a3b2ba 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -4299,6 +4299,8 @@ cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
new_queue:
cfqq = cic_to_cfqq(cic, is_sync);
if (!cfqq || cfqq == &cfqd->oom_cfqq) {
+ if (cfqq)
+ cfq_put_queue(cfqq);
cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
cic_set_cfqq(cic, cfqq, is_sync);
} else {