From: Konstantin Khlebnikov Date: Mon, 9 Feb 2015 13:42:49 +0000 (+0300) Subject: cfq-iosched: handle failure of cfq group allocation X-Git-Tag: fixes-v4.0-rc1~118^2~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69abaffec7d47a083739b79e3066cb3730eba72e;p=pandora-kernel.git 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 Acked-by: Tejun Heo Acked-by: Vivek Goyal Fixes: cd1604fab4f9 ("blkcg: factor out blkio_group creation") Cc: stable@kernel.org Signed-off-by: Jens Axboe --- Reading git-diff-tree failed