Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 035/175] cfq-iosched: handle failure of cfq group allocation | Date | Tue, 17 Mar 2015 09:40:13 +0100 |
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From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
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: Jiri Slaby <jslaby@suse.cz> --- block/cfq-iosched.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 06c2bab69756..396bff25226b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3575,6 +3575,11 @@ 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); /* @@ -3611,7 +3616,7 @@ retry: } else cfqq = &cfqd->oom_cfqq; } - +out: if (new_cfqq) kmem_cache_free(cfq_pool, new_cfqq); -- 2.3.0
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