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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Paolo Valente <paolo.valente@linaro.org>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 4.14 005/126] block: bfq: swap puts in bfqg_and_blkg_put
Date:   Tue, 18 Sep 2018 00:40:53 +0200
Message-Id: <20180917211704.041746135@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

commit d5274b3cd6a814ccb2f56d81ee87cbbf51bd4cf7 upstream.

Fix trivial use-after-free. This could be last reference to bfqg.

Fixes: 8f9bebc33dd7 ("block, bfq: access and cache blkg data only when safe")
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 block/bfq-cgroup.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -224,9 +224,9 @@ static void bfqg_and_blkg_get(struct bfq
 
 void bfqg_and_blkg_put(struct bfq_group *bfqg)
 {
-	bfqg_put(bfqg);
-
 	blkg_put(bfqg_to_blkg(bfqg));
+
+	bfqg_put(bfqg);
 }
 
 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,