BACKPORT: blk-mq: clear stale request in tags->rq[] before freeing one request pool
refcount_inc_not_zero() in bt_tags_iter() still may read one freed
request.
Fix the issue by the following approach:
1) hold a per-tags spinlock when reading ->rqs[tag] and calling
refcount_inc_not_zero in bt_tags_iter()
2) clearing stale request referred via ->rqs[tag] before freeing
request pool, the per-tags spinlock is held for clearing stale
->rq[tag]
So after we cleared stale requests, bt_tags_iter() won't observe
freed request any more, also the clearing will wait for pending
request reference.
The idea of clearing ->rqs[] is borrowed from John Garry's previous
patch and one recent David's patch.
Tested-by: John Garry <john.garry@huawei.com>
Reviewed-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>.
Bug: 197804811
Change-Id: If49478d7b05d3f5b0a26966ddf9ae764cf2fb6b0
[Upstream: cherry picked from commit bd63141d585bef14f4caf111f6d0e27fe2300ec6]
[Todd: refactored to avoid breaking KMI ]
Signed-off-by: Pradeep P V K <pragalla@codeaurora.org>
Signed-off-by: Todd Kjos <tkjos@google.com>
Git-commit: bb96e7f45dc6ac1d6ec12190f1f286e3014fb068
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Pradeep P V K <quic_pragalla@quicinc.com>
(cherry picked from commit 02c9fbde9b
)
Change-Id: I58693eddf77156f574a80542f719bd132906f0cc
Signed-off-by: Surapusetty Naresh Babu <snareshb@qti.qualcomm.com>
This commit is contained in:
parent
66b99c5dad
commit
70249194f9
3 changed files with 54 additions and 8 deletions
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@ -221,10 +221,14 @@ struct bt_iter_data {
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static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags,
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unsigned int bitnr)
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{
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struct request *rq = tags->rqs[bitnr];
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struct request *rq;
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unsigned long flags;
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spin_lock_irqsave(&tags->lock, flags);
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rq = tags->rqs[bitnr];
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if (!rq || !refcount_inc_not_zero(&rq->ref))
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return NULL;
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rq = NULL;
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spin_unlock_irqrestore(&tags->lock, flags);
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return rq;
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}
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@ -407,6 +411,7 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
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tags->nr_tags = total_tags;
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tags->nr_reserved_tags = reserved_tags;
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spin_lock_init(&tags->lock);
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return blk_mq_init_bitmap_tags(tags, node, alloc_policy);
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}
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@ -19,8 +19,13 @@ struct blk_mq_tags {
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struct request **rqs;
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struct request **static_rqs;
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struct list_head page_list;
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};
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/*
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* used to clear request reference in rqs[] before freeing one
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* request pool
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*/
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spinlock_t lock;
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};
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extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node, int alloc_policy);
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extern void blk_mq_free_tags(struct blk_mq_tags *tags);
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@ -1836,6 +1836,45 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
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}
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}
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static size_t order_to_size(unsigned int order)
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{
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return (size_t)PAGE_SIZE << order;
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}
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/* called before freeing request pool in @tags */
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static void blk_mq_clear_rq_mapping(struct blk_mq_tag_set *set,
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struct blk_mq_tags *tags, unsigned int hctx_idx)
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{
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struct blk_mq_tags *drv_tags = set->tags[hctx_idx];
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struct page *page;
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unsigned long flags;
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list_for_each_entry(page, &tags->page_list, lru) {
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unsigned long start = (unsigned long)page_address(page);
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unsigned long end = start + order_to_size(page->private);
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int i;
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for (i = 0; i < set->queue_depth; i++) {
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struct request *rq = drv_tags->rqs[i];
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unsigned long rq_addr = (unsigned long)rq;
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if (rq_addr >= start && rq_addr < end) {
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WARN_ON_ONCE(refcount_read(&rq->ref) != 0);
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cmpxchg(&drv_tags->rqs[i], rq, NULL);
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}
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}
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}
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/*
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* Wait until all pending iteration is done.
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*
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* Request reference is cleared and it is guaranteed to be observed
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* after the ->lock is released.
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*/
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spin_lock_irqsave(&drv_tags->lock, flags);
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spin_unlock_irqrestore(&drv_tags->lock, flags);
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}
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static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
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{
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const int is_sync = op_is_sync(bio->bi_opf);
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@ -1968,6 +2007,8 @@ void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
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}
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}
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blk_mq_clear_rq_mapping(set, tags, hctx_idx);
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while (!list_empty(&tags->page_list)) {
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page = list_first_entry(&tags->page_list, struct page, lru);
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list_del_init(&page->lru);
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@ -2027,11 +2068,6 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
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return tags;
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}
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static size_t order_to_size(unsigned int order)
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{
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return (size_t)PAGE_SIZE << order;
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}
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static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
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unsigned int hctx_idx, int node)
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{
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