path: root/block
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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2015-02-09 16:42:49 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-06 14:43:29 -0800
commit16f3a871c431a52d1461e88cf3c0d2e828366930 (patch)
tree4400701772fdfe05e0ef357fcf4b03c14351d82d /block
parenteec188a371a6ad6f8f7188980d08918f0e4256ee (diff)
cfq-iosched: handle failure of cfq group allocation
commit 69abaffec7d47a083739b79e3066cb3730eba72e upstream. 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") Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
1 files changed, 6 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 91c25f261c91..de66a476e356 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3585,6 +3585,11 @@ 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);
@@ -3621,7 +3626,7 @@ retry:
} else
cfqq = &cfqd->oom_cfqq;
if (new_cfqq)
kmem_cache_free(cfq_pool, new_cfqq);