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SubjectRe: [BUGFIX 1/1] block, bfq: handle NULL return value by bfq_init_rq()
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On 8/7/19 10:21 AM, Paolo Valente wrote:
> 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
>
> Reported-by: Guenter Roeck <linux@roeck-us.net>
> Reported-by: Hsin-Yi Wang <hsinyi@google.com>
> Cc: Hsin-Yi Wang <hsinyi@google.com>
> Cc: Nicolas Boichat <drinkcat@chromium.org>
> Cc: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 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 586fcfe227ea..32686300d89b 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -2250,9 +2250,14 @@ 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);
> @@ -2299,6 +2304,9 @@ 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
> @@ -5436,12 +5444,12 @@ 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
>

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