[PATCH 5.2 102/162] block, bfq: handle NULL return value by bfq_init_rq()

Greg Kroah-Hartman
2019-08-27T08:04:17Z

[ Upstream commit fd03177c33b287c6541f4048f1d67b7b45a1abc9 ]

As reported in [1], the call bfq_init_rq(rq) may return NULL in case
of OOM (in particular, if rq->elv.icq is NULL because memory
allocation failed in failed in ioc_create_icq()).

This commit handles this circumstance.

[1] https://lkml.org/lkml/2019/7/22/824

Cc: Hsin-Yi Wang <hsinyi@google.com>
Cc: Nicolas Boichat <drinkcat@chromium.org>
Cc: Doug Anderson <dianders@chromium.org>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Hsin-Yi Wang <hsinyi@google.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/bfq-iosched.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 404e776aa36d0..b528710364e9e 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2085,9 +2085,14 @@ static void bfq_request_merged(struct request_queue *q, struct request *req,
blk_rq_pos(container_of(rb_prev(&req->rb_node),
struct request, rb_node))) {
struct bfq_queue *bfqq = bfq_init_rq(req);
- struct bfq_data *bfqd = bfqq->bfqd;
+ struct bfq_data *bfqd;
struct request *prev, *next_rq;

+ if (!bfqq)
+ return;
+
+ bfqd = bfqq->bfqd;
+
/* Reposition request in its sort_list */
elv_rb_del(&bfqq->sort_list, req);
elv_rb_add(&bfqq->sort_list, req);
@@ -2134,6 +2139,9 @@ static void bfq_requests_merged(struct request_queue *q, struct request *rq,
struct bfq_queue *bfqq = bfq_init_rq(rq),
*next_bfqq = bfq_init_rq(next);

+ if (!bfqq)
+ return;
+
/*
* If next and rq belong to the same bfq_queue and next is older
* than rq, then reposition rq in the fifo (by substituting next
@@ -5061,12 +5069,12 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,

spin_lock_irq(&bfqd->lock);
bfqq = bfq_init_rq(rq);
- if (at_head || blk_rq_is_passthrough(rq)) {
+ if (!bfqq || at_head || blk_rq_is_passthrough(rq)) {
if (at_head)
list_add(&rq->queuelist, &bfqd->dispatch);
else
list_add_tail(&rq->queuelist, &bfqd->dispatch);
- } else { /* bfqq is assumed to be non null here */
+ } else {
idle_timer_disabled = __bfq_insert_request(bfqd, rq);
/*
* Update bfqq, because, if a queue merge has occurred
--
2.20.1