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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2015-02-09 16:42:49 +0300
committerJens Axboe <axboe@fb.com>2015-02-09 10:22:39 -0700
commit69abaffec7d47a083739b79e3066cb3730eba72e (patch)
treee217ce01355ab8b2ca1d58c54c983fda70e026f2
parent9f9ee1f2b2f94f19437ae2def7c0d6636d7fe02e (diff)
downloadop-kernel-dev-69abaffec7d47a083739b79e3066cb3730eba72e.zip
op-kernel-dev-69abaffec7d47a083739b79e3066cb3730eba72e.tar.gz
cfq-iosched: handle failure of cfq group allocation
Cfq_lookup_create_cfqg() allocates struct blkcg_gq using GFP_ATOMIC. In cfq_find_alloc_queue() possible allocation failure is not handled. As a result kernel oopses on NULL pointer dereference when cfq_link_cfqq_cfqg() calls cfqg_get() for NULL pointer. Bug was introduced in v3.5 in commit cd1604fab4f9 ("blkcg: factor out blkio_group creation"). Prior to that commit cfq group lookup had returned pointer to root group as fallback. This patch handles this error using existing fallback oom_cfqq. Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com> Fixes: cd1604fab4f9 ("blkcg: factor out blkio_group creation") Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--block/cfq-iosched.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b9abdca..5da8e6e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3590,6 +3590,11 @@ retry:
blkcg = bio_blkcg(bio);
cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
+ if (!cfqg) {
+ cfqq = &cfqd->oom_cfqq;
+ goto out;
+ }
+
cfqq = cic_to_cfqq(cic, is_sync);
/*
@@ -3626,7 +3631,7 @@ retry:
} else
cfqq = &cfqd->oom_cfqq;
}
-
+out:
if (new_cfqq)
kmem_cache_free(cfq_pool, new_cfqq);
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