Re: [PATCH v26 2/4] scsi: ufs: L2P map management for HPB read

[Can Guo <cang@codeaurora.org>]

On 2021-03-12 09:48, Daejun Park wrote:
>> > This is a patch for managing L2P map in HPB module.
>> >
>> > The HPB divides logical addresses into several regions. A region
>> > consists
>> > of several sub-regions. The sub-region is a basic unit where L2P
>> > mapping is
>> > managed. The driver loads L2P mapping data of each sub-region. The
>> > loaded
>> > sub-region is called active-state. The HPB driver unloads L2P mapping
>> > data
>> > as region unit. The unloaded region is called inactive-state.
>> >
>> > Sub-region/region candidates to be loaded and unloaded are delivered
>> > from
>> > the UFS device. The UFS device delivers the recommended active
>> > sub-region
>> > and inactivate region to the driver using sensedata.
>> > The HPB module performs L2P mapping management on the host through the
>> > delivered information.
>> >
>> > A pinned region is a pre-set regions on the UFS device that is always
>> > activate-state.
>> >
>> > The data structure for map data request and L2P map uses mempool API,
>> > minimizing allocation overhead while avoiding static allocation.
>> >
>> > The mininum size of the memory pool used in the HPB is implemented
>> > as a module parameter, so that it can be configurable by the user.
>> >
>> > To gurantee a minimum memory pool size of 4MB:
>> > ufshpb_host_map_kbytes=4096
>> >
>> > The map_work manages active/inactive by 2 "to-do" lists.
>> > Each hpb lun maintains 2 "to-do" lists:
>> >   hpb->lh_inact_rgn - regions to be inactivated, and
>> >   hpb->lh_act_srgn - subregions to be activated
>> > Those lists are maintained on IO completion.
>> >
>> > Reviewed-by: Bart Van Assche <bvanassche@acm.org>
>> > Reviewed-by: Can Guo <cang@codeaurora.org>
>> > Acked-by: Avri Altman <Avri.Altman@wdc.com>
>> > Tested-by: Bean Huo <beanhuo@micron.com>
>> > Signed-off-by: Daejun Park <daejun7.park@samsung.com>
>> > ---
>> >  drivers/scsi/ufs/ufs.h    |   36 ++
>> >  drivers/scsi/ufs/ufshcd.c |    4 +
>> >  drivers/scsi/ufs/ufshpb.c | 1091 ++++++++++++++++++++++++++++++++++++-
>> >  drivers/scsi/ufs/ufshpb.h |   65 +++
>> >  4 files changed, 1181 insertions(+), 15 deletions(-)
>> >
>> > diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
>> > index 65563635e20e..957763db1006 100644
>> > --- a/drivers/scsi/ufs/ufs.h
>> > +++ b/drivers/scsi/ufs/ufs.h
>> > @@ -472,6 +472,41 @@ struct utp_cmd_rsp {
>> >          u8 sense_data[UFS_SENSE_SIZE];
>> >  };
>> >
>> > +struct ufshpb_active_field {
>> > +        __be16 active_rgn;
>> > +        __be16 active_srgn;
>> > +};
>> > +#define HPB_ACT_FIELD_SIZE 4
>> > +
>> > +/**
>> > + * struct utp_hpb_rsp - Response UPIU structure
>> > + * @residual_transfer_count: Residual transfer count DW-3
>> > + * @reserved1: Reserved double words DW-4 to DW-7
>> > + * @sense_data_len: Sense data length DW-8 U16
>> > + * @desc_type: Descriptor type of sense data
>> > + * @additional_len: Additional length of sense data
>> > + * @hpb_op: HPB operation type
>> > + * @lun: LUN of response UPIU
>> > + * @active_rgn_cnt: Active region count
>> > + * @inactive_rgn_cnt: Inactive region count
>> > + * @hpb_active_field: Recommended to read HPB region and subregion
>> > + * @hpb_inactive_field: To be inactivated HPB region and subregion
>> > + */
>> > +struct utp_hpb_rsp {
>> > +        __be32 residual_transfer_count;
>> > +        __be32 reserved1[4];
>> > +        __be16 sense_data_len;
>> > +        u8 desc_type;
>> > +        u8 additional_len;
>> > +        u8 hpb_op;
>> > +        u8 lun;
>> > +        u8 active_rgn_cnt;
>> > +        u8 inactive_rgn_cnt;
>> > +        struct ufshpb_active_field hpb_active_field[2];
>> > +        __be16 hpb_inactive_field[2];
>> > +};
>> > +#define UTP_HPB_RSP_SIZE 40
>> > +
>> >  /**
>> >   * struct utp_upiu_rsp - general upiu response structure
>> >   * @header: UPIU header structure DW-0 to DW-2
>> > @@ -482,6 +517,7 @@ struct utp_upiu_rsp {
>> >          struct utp_upiu_header header;
>> >          union {
>> >                  struct utp_cmd_rsp sr;
>> > +                struct utp_hpb_rsp hr;
>> >                  struct utp_upiu_query qr;
>> >          };
>> >  };
>> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> > index 49b3d5d24fa6..5852ff44c3cc 100644
>> > --- a/drivers/scsi/ufs/ufshcd.c
>> > +++ b/drivers/scsi/ufs/ufshcd.c
>> > @@ -5021,6 +5021,9 @@ ufshcd_transfer_rsp_status(struct ufs_hba *hba,
>> > struct ufshcd_lrb *lrbp)
>> >                                   */
>> >                                  pm_runtime_get_noresume(hba->dev);
>> >                          }
>> > +
>> > +                        if (scsi_status == SAM_STAT_GOOD)
>> > +                                ufshpb_rsp_upiu(hba, lrbp);
>> >                          break;
>> >                  case UPIU_TRANSACTION_REJECT_UPIU:
>> >                          /* TODO: handle Reject UPIU Response */
>> > @@ -9221,6 +9224,7 @@ EXPORT_SYMBOL(ufshcd_shutdown);
>> >  void ufshcd_remove(struct ufs_hba *hba)
>> >  {
>> >          ufs_bsg_remove(hba);
>> > +        ufshpb_remove(hba);
>> >          ufs_sysfs_remove_nodes(hba->dev);
>> >          blk_cleanup_queue(hba->tmf_queue);
>> >          blk_mq_free_tag_set(&hba->tmf_tag_set);
>> > diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
>> > index 1a72f6541510..8abadb0e010a 100644
>> > --- a/drivers/scsi/ufs/ufshpb.c
>> > +++ b/drivers/scsi/ufs/ufshpb.c
>> > @@ -16,6 +16,16 @@
>> >  #include "ufshpb.h"
>> >  #include "../sd.h"
>> >
>> > +/* memory management */
>> > +static struct kmem_cache *ufshpb_mctx_cache;
>> > +static mempool_t *ufshpb_mctx_pool;
>> > +static mempool_t *ufshpb_page_pool;
>> > +/* A cache size of 2MB can cache ppn in the 1GB range. */
>> > +static unsigned int ufshpb_host_map_kbytes = 2048;
>> > +static int tot_active_srgn_pages;
>> > +
>> > +static struct workqueue_struct *ufshpb_wq;
>> > +
>> >  bool ufshpb_is_allowed(struct ufs_hba *hba)
>> >  {
>> >          return !(hba->ufshpb_dev.hpb_disabled);
>> > @@ -36,14 +46,892 @@ static void ufshpb_set_state(struct ufshpb_lu
>> > *hpb, int state)
>> >          atomic_set(&hpb->hpb_state, state);
>> >  }
>> >
>> > +static bool ufshpb_is_general_lun(int lun)
>> > +{
>> > +        return lun < UFS_UPIU_MAX_UNIT_NUM_ID;
>> > +}
>> > +
>> > +static bool
>> > +ufshpb_is_pinned_region(struct ufshpb_lu *hpb, int rgn_idx)
>> > +{
>> > +        if (hpb->lu_pinned_end != PINNED_NOT_SET &&
>> > +            rgn_idx >= hpb->lu_pinned_start &&
>> > +            rgn_idx <= hpb->lu_pinned_end)
>> > +                return true;
>> > +
>> > +        return false;
>> > +}
>> > +
>> > +static void ufshpb_kick_map_work(struct ufshpb_lu *hpb)
>> > +{
>> > +        bool ret = false;
>> > +        unsigned long flags;
>> > +
>> > +        if (ufshpb_get_state(hpb) != HPB_PRESENT)
>> > +                return;
>> > +
>> > +        spin_lock_irqsave(&hpb->rsp_list_lock, flags);
>> > +        if (!list_empty(&hpb->lh_inact_rgn) ||
>> > !list_empty(&hpb->lh_act_srgn))
>> > +                ret = true;
>> > +        spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
>> > +
>> > +        if (ret)
>> > +                queue_work(ufshpb_wq, &hpb->map_work);
>> > +}
>> > +
>> > +static bool ufshpb_is_hpb_rsp_valid(struct ufs_hba *hba,
>> > +                                         struct ufshcd_lrb *lrbp,
>> > +                                         struct utp_hpb_rsp *rsp_field)
>> > +{
>> > +        /* Check HPB_UPDATE_ALERT */
>> > +        if (!(lrbp->ucd_rsp_ptr->header.dword_2 &
>> > +              UPIU_HEADER_DWORD(0, 2, 0, 0)))
>> > +                return false;
>> > +
>> > +        if (be16_to_cpu(rsp_field->sense_data_len) != DEV_SENSE_SEG_LEN ||
>> > +            rsp_field->desc_type != DEV_DES_TYPE ||
>> > +            rsp_field->additional_len != DEV_ADDITIONAL_LEN ||
>> > +            rsp_field->active_rgn_cnt > MAX_ACTIVE_NUM ||
>> > +            rsp_field->inactive_rgn_cnt > MAX_INACTIVE_NUM ||
>> > +            rsp_field->hpb_op == HPB_RSP_NONE ||
>> > +            (rsp_field->hpb_op == HPB_RSP_REQ_REGION_UPDATE &&
>> > +             !rsp_field->active_rgn_cnt && !rsp_field->inactive_rgn_cnt))
>> > +                return false;
>> > +
>> > +        if (!ufshpb_is_general_lun(rsp_field->lun)) {
>> > +                dev_warn(hba->dev, "ufshpb: lun(%d) not supported\n",
>> > +                         lrbp->lun);
>> > +                return false;
>> > +        }
>> > +
>> > +        return true;
>> > +}
>> > +
>> > +static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
>> > +                                             struct ufshpb_subregion *srgn)
>> > +{
>> > +        struct ufshpb_req *map_req;
>> > +        struct request *req;
>> > +        struct bio *bio;
>> > +        int retries = HPB_MAP_REQ_RETRIES;
>> > +
>> > +        map_req = kmem_cache_alloc(hpb->map_req_cache, GFP_KERNEL);
>> > +        if (!map_req)
>> > +                return NULL;
>> > +
>> > +retry:
>> > +        req = blk_get_request(hpb->sdev_ufs_lu->request_queue,
>> > +                              REQ_OP_SCSI_IN, BLK_MQ_REQ_NOWAIT);
>> > +
>> > +        if ((PTR_ERR(req) == -EWOULDBLOCK) && (--retries > 0)) {
>> > +                usleep_range(3000, 3100);
>> > +                goto retry;
>> > +        }
>> > +
>> > +        if (IS_ERR(req))
>> > +                goto free_map_req;
>> > +
>> > +        bio = bio_alloc(GFP_KERNEL, hpb->pages_per_srgn);
>> > +        if (!bio) {
>> > +                blk_put_request(req);
>> > +                goto free_map_req;
>> > +        }
>> > +
>> > +        map_req->hpb = hpb;
>> > +        map_req->req = req;
>> > +        map_req->bio = bio;
>> > +
>> > +        map_req->rgn_idx = srgn->rgn_idx;
>> > +        map_req->srgn_idx = srgn->srgn_idx;
>> > +        map_req->mctx = srgn->mctx;
>> > +
>> > +        return map_req;
>> > +
>> > +free_map_req:
>> > +        kmem_cache_free(hpb->map_req_cache, map_req);
>> > +        return NULL;
>> > +}
>> > +
>> > +static void ufshpb_put_map_req(struct ufshpb_lu *hpb,
>> > +                                      struct ufshpb_req *map_req)
>> > +{
>> > +        bio_put(map_req->bio);
>> > +        blk_put_request(map_req->req);
>> > +        kmem_cache_free(hpb->map_req_cache, map_req);
>> > +}
>> > +
>> > +static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
>> > +                                     struct ufshpb_subregion *srgn)
>> > +{
>> > +        u32 num_entries = hpb->entries_per_srgn;
>> > +
>> > +        if (!srgn->mctx) {
>> > +                dev_err(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                        "no mctx in region %d subregion %d.\n",
>> > +                        srgn->rgn_idx, srgn->srgn_idx);
>> > +                return -1;
>> > +        }
>> > +
>> > +        if (unlikely(srgn->is_last))
>> > +                num_entries = hpb->last_srgn_entries;
>> > +
>> > +        bitmap_zero(srgn->mctx->ppn_dirty, num_entries);
>> > +        return 0;
>> > +}
>> > +
>> > +static void ufshpb_update_active_info(struct ufshpb_lu *hpb, int
>> > rgn_idx,
>> > +                                      int srgn_idx)
>> > +{
>> > +        struct ufshpb_region *rgn;
>> > +        struct ufshpb_subregion *srgn;
>> > +
>> > +        rgn = hpb->rgn_tbl + rgn_idx;
>> > +        srgn = rgn->srgn_tbl + srgn_idx;
>> > +
>> > +        list_del_init(&rgn->list_inact_rgn);
>> > +
>> > +        if (list_empty(&srgn->list_act_srgn))
>> > +                list_add_tail(&srgn->list_act_srgn, &hpb->lh_act_srgn);
>> > +}
>> > +
>> > +static void ufshpb_update_inactive_info(struct ufshpb_lu *hpb, int
>> > rgn_idx)
>> > +{
>> > +        struct ufshpb_region *rgn;
>> > +        struct ufshpb_subregion *srgn;
>> > +        int srgn_idx;
>> > +
>> > +        rgn = hpb->rgn_tbl + rgn_idx;
>> > +
>> > +        for_each_sub_region(rgn, srgn_idx, srgn)
>> > +                list_del_init(&srgn->list_act_srgn);
>> > +
>> > +        if (list_empty(&rgn->list_inact_rgn))
>> > +                list_add_tail(&rgn->list_inact_rgn, &hpb->lh_inact_rgn);
>> > +}
>> > +
>> > +static void ufshpb_activate_subregion(struct ufshpb_lu *hpb,
>> > +                                      struct ufshpb_subregion *srgn)
>> > +{
>> > +        struct ufshpb_region *rgn;
>> > +
>> > +        /*
>> > +         * If there is no mctx in subregion
>> > +         * after I/O progress for HPB_READ_BUFFER, the region to which the
>> > +         * subregion belongs was evicted.
>> > +         * Make sure the region must not evict in I/O progress
>> > +         */
>> > +        if (!srgn->mctx) {
>> > +                dev_err(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                        "no mctx in region %d subregion %d.\n",
>> > +                        srgn->rgn_idx, srgn->srgn_idx);
>> > +                srgn->srgn_state = HPB_SRGN_INVALID;
>> > +                return;
>> > +        }
>> > +
>> > +        rgn = hpb->rgn_tbl + srgn->rgn_idx;
>> > +
>> > +        if (unlikely(rgn->rgn_state == HPB_RGN_INACTIVE)) {
>> > +                dev_err(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                        "region %d subregion %d evicted\n",
>> > +                        srgn->rgn_idx, srgn->srgn_idx);
>> > +                srgn->srgn_state = HPB_SRGN_INVALID;
>> > +                return;
>> > +        }
>> > +        srgn->srgn_state = HPB_SRGN_VALID;
>> > +}
>> > +
>> > +static void ufshpb_map_req_compl_fn(struct request *req, blk_status_t
>> > error)
>> > +{
>> > +        struct ufshpb_req *map_req = (struct ufshpb_req *) req->end_io_data;
>> > +        struct ufshpb_lu *hpb = map_req->hpb;
>> > +        struct ufshpb_subregion *srgn;
>> > +        unsigned long flags;
>> > +
>> > +        srgn = hpb->rgn_tbl[map_req->rgn_idx].srgn_tbl +
>> > +                map_req->srgn_idx;
>> > +
>> > +        ufshpb_clear_dirty_bitmap(hpb, srgn);
>> > +        spin_lock_irqsave(&hpb->rgn_state_lock, flags);
>> > +        ufshpb_activate_subregion(hpb, srgn);
>> > +        spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
>> > +
>> > +        ufshpb_put_map_req(map_req->hpb, map_req);
>> > +}
>> > +
>> > +static void ufshpb_set_read_buf_cmd(unsigned char *cdb, int rgn_idx,
>> > +                                    int srgn_idx, int srgn_mem_size)
>> > +{
>> > +        cdb[0] = UFSHPB_READ_BUFFER;
>> > +        cdb[1] = UFSHPB_READ_BUFFER_ID;
>> > +
>> > +        put_unaligned_be16(rgn_idx, &cdb[2]);
>> > +        put_unaligned_be16(srgn_idx, &cdb[4]);
>> > +        put_unaligned_be24(srgn_mem_size, &cdb[6]);
>> > +
>> > +        cdb[9] = 0x00;
>> > +}
>> > +
>> > +static int ufshpb_execute_map_req(struct ufshpb_lu *hpb,
>> > +                                  struct ufshpb_req *map_req, bool last)
>> > +{
>> > +        struct request_queue *q;
>> > +        struct request *req;
>> > +        struct scsi_request *rq;
>> > +        int mem_size = hpb->srgn_mem_size;
>> > +        int ret = 0;
>> > +        int i;
>> > +
>> > +        q = hpb->sdev_ufs_lu->request_queue;
>> > +        for (i = 0; i < hpb->pages_per_srgn; i++) {
>> > +                ret = bio_add_pc_page(q, map_req->bio, map_req->mctx->m_page[i],
>> > +                                      PAGE_SIZE, 0);
>> > +                if (ret != PAGE_SIZE) {
>> > +                        dev_err(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                                   "bio_add_pc_page fail %d - %d\n",
>> > +                                   map_req->rgn_idx, map_req->srgn_idx);
>> > +                        return ret;
>> > +                }
>> > +        }
>> > +
>> > +        req = map_req->req;
>> > +
>> > +        blk_rq_append_bio(req, &map_req->bio);
>> > +
>> > +        req->end_io_data = map_req;
>> > +
>> > +        rq = scsi_req(req);
>> > +
>> > +        if (unlikely(last))
>> > +                mem_size = hpb->last_srgn_entries * HPB_ENTRY_SIZE;
>> > +
>> > +        ufshpb_set_read_buf_cmd(rq->cmd, map_req->rgn_idx,
>> > +                                map_req->srgn_idx, mem_size);
>> > +        rq->cmd_len = HPB_READ_BUFFER_CMD_LENGTH;
>> > +
>> > +        blk_execute_rq_nowait(q, NULL, req, 1, ufshpb_map_req_compl_fn);
>> > +
>> > +        hpb->stats.map_req_cnt++;
>> > +        return 0;
>> > +}
>> > +
>> > +static struct ufshpb_map_ctx *ufshpb_get_map_ctx(struct ufshpb_lu
>> > *hpb,
>> > +                                                 bool last)
>> > +{
>> > +        struct ufshpb_map_ctx *mctx;
>> > +        u32 num_entries = hpb->entries_per_srgn;
>> > +        int i, j;
>> > +
>> > +        mctx = mempool_alloc(ufshpb_mctx_pool, GFP_KERNEL);
>> > +        if (!mctx)
>> > +                return NULL;
>> > +
>> > +        mctx->m_page = kmem_cache_alloc(hpb->m_page_cache, GFP_KERNEL);
>> > +        if (!mctx->m_page)
>> > +                goto release_mctx;
>> > +
>> > +        if (unlikely(last))
>> > +                num_entries = hpb->last_srgn_entries;
>> > +
>> > +        mctx->ppn_dirty = bitmap_zalloc(num_entries, GFP_KERNEL);
>> > +        if (!mctx->ppn_dirty)
>> > +                goto release_m_page;
>> > +
>> > +        for (i = 0; i < hpb->pages_per_srgn; i++) {
>> > +                mctx->m_page[i] = mempool_alloc(ufshpb_page_pool, GFP_KERNEL);
>> > +                if (!mctx->m_page[i]) {
>> > +                        for (j = 0; j < i; j++)
>> > +                                mempool_free(mctx->m_page[j], ufshpb_page_pool);
>> > +                        goto release_ppn_dirty;
>> > +                }
>> > +                clear_page(page_address(mctx->m_page[i]));
>> > +        }
>> > +
>> > +        return mctx;
>> > +
>> > +release_ppn_dirty:
>> > +        bitmap_free(mctx->ppn_dirty);
>> > +release_m_page:
>> > +        kmem_cache_free(hpb->m_page_cache, mctx->m_page);
>> > +release_mctx:
>> > +        mempool_free(mctx, ufshpb_mctx_pool);
>> > +        return NULL;
>> > +}
>> > +
>> > +static void ufshpb_put_map_ctx(struct ufshpb_lu *hpb,
>> > +                               struct ufshpb_map_ctx *mctx)
>> > +{
>> > +        int i;
>> > +
>> > +        for (i = 0; i < hpb->pages_per_srgn; i++)
>> > +                mempool_free(mctx->m_page[i], ufshpb_page_pool);
>> > +
>> > +        bitmap_free(mctx->ppn_dirty);
>> > +        kmem_cache_free(hpb->m_page_cache, mctx->m_page);
>> > +        mempool_free(mctx, ufshpb_mctx_pool);
>> > +}
>> > +
>> > +static int ufshpb_check_srgns_issue_state(struct ufshpb_lu *hpb,
>> > +                                          struct ufshpb_region *rgn)
>> > +{
>> > +        struct ufshpb_subregion *srgn;
>> > +        int srgn_idx;
>> > +
>> > +        for_each_sub_region(rgn, srgn_idx, srgn)
>> > +                if (srgn->srgn_state == HPB_SRGN_ISSUED)
>> > +                        return -EPERM;
>> > +
>> > +        return 0;
>> > +}
>> > +
>> > +static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
>> > +                                struct ufshpb_region *rgn)
>> > +{
>> > +        rgn->rgn_state = HPB_RGN_ACTIVE;
>> > +        list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
>> > +        atomic_inc(&lru_info->active_cnt);
>> > +}
>> > +
>> > +static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
>> > +                                struct ufshpb_region *rgn)
>> > +{
>> > +        list_move_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
>> > +}
>> > +
>> > +static struct ufshpb_region *ufshpb_victim_lru_info(struct ufshpb_lu
>> > *hpb)
>> > +{
>> > +        struct victim_select_info *lru_info = &hpb->lru_info;
>> > +        struct ufshpb_region *rgn, *victim_rgn = NULL;
>> > +
>> > +        list_for_each_entry(rgn, &lru_info->lh_lru_rgn, list_lru_rgn) {
>> > +                if (!rgn) {
>> > +                        dev_err(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                                "%s: no region allocated\n",
>> > +                                __func__);
>> > +                        return NULL;
>> > +                }
>> > +                if (ufshpb_check_srgns_issue_state(hpb, rgn))
>> > +                        continue;
>> > +
>> > +                victim_rgn = rgn;
>> > +                break;
>> > +        }
>> > +
>> > +        return victim_rgn;
>> > +}
>> > +
>> > +static void ufshpb_cleanup_lru_info(struct victim_select_info
>> > *lru_info,
>> > +                                    struct ufshpb_region *rgn)
>> > +{
>> > +        list_del_init(&rgn->list_lru_rgn);
>> > +        rgn->rgn_state = HPB_RGN_INACTIVE;
>> > +        atomic_dec(&lru_info->active_cnt);
>> > +}
>> > +
>> > +static void ufshpb_purge_active_subregion(struct ufshpb_lu *hpb,
>> > +                                          struct ufshpb_subregion *srgn)
>> > +{
>> > +        if (srgn->srgn_state != HPB_SRGN_UNUSED) {
>> > +                ufshpb_put_map_ctx(hpb, srgn->mctx);
>> > +                srgn->srgn_state = HPB_SRGN_UNUSED;
>> > +                srgn->mctx = NULL;
>> > +        }
>> > +}
>> > +
>> > +static void __ufshpb_evict_region(struct ufshpb_lu *hpb,
>> > +                                  struct ufshpb_region *rgn)
>> > +{
>> > +        struct victim_select_info *lru_info;
>> > +        struct ufshpb_subregion *srgn;
>> > +        int srgn_idx;
>> > +
>> > +        lru_info = &hpb->lru_info;
>> > +
>> > +        dev_dbg(&hpb->sdev_ufs_lu->sdev_dev, "evict region %d\n",
>> > rgn->rgn_idx);
>> > +
>> > +        ufshpb_cleanup_lru_info(lru_info, rgn);
>> > +
>> > +        for_each_sub_region(rgn, srgn_idx, srgn)
>> > +                ufshpb_purge_active_subregion(hpb, srgn);
>> > +}
>> > +
>> > +static int ufshpb_evict_region(struct ufshpb_lu *hpb, struct
>> > ufshpb_region *rgn)
>> > +{
>> > +        unsigned long flags;
>> > +        int ret = 0;
>> > +
>> > +        spin_lock_irqsave(&hpb->rgn_state_lock, flags);
>> > +        if (rgn->rgn_state == HPB_RGN_PINNED) {
>> > +                dev_warn(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                         "pinned region cannot drop-out. region %d\n",
>> > +                         rgn->rgn_idx);
>> > +                goto out;
>> > +        }
>> > +        if (!list_empty(&rgn->list_lru_rgn)) {
>> > +                if (ufshpb_check_srgns_issue_state(hpb, rgn)) {
>> > +                        ret = -EBUSY;
>> > +                        goto out;
>> > +                }
>> > +
>> > +                __ufshpb_evict_region(hpb, rgn);
>> > +        }
>> > +out:
>> > +        spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
>> > +        return ret;
>> > +}
>> > +
>> > +static int ufshpb_issue_map_req(struct ufshpb_lu *hpb,
>> > +                                struct ufshpb_region *rgn,
>> > +                                struct ufshpb_subregion *srgn)
>> > +{
>> > +        struct ufshpb_req *map_req;
>> > +        unsigned long flags;
>> > +        int ret;
>> > +        int err = -EAGAIN;
>> > +        bool alloc_required = false;
>> > +        enum HPB_SRGN_STATE state = HPB_SRGN_INVALID;
>> > +
>> > +        spin_lock_irqsave(&hpb->rgn_state_lock, flags);
>> > +
>> > +        if (ufshpb_get_state(hpb) != HPB_PRESENT) {
>> > +                dev_notice(&hpb->sdev_ufs_lu->sdev_dev,
>> > +                           "%s: ufshpb state is not PRESENT\n", __func__);
>> > +                goto unlock_out;
>> > +        }
>> > +
>> > +        if ((rgn->rgn_state == HPB_RGN_INACTIVE) &&
>> > +            (srgn->srgn_state == HPB_SRGN_INVALID)) {
>> > +                err = 0;
>> > +                goto unlock_out;
>> > +        }
>> > +
>> > +        if (srgn->srgn_state == HPB_SRGN_UNUSED)
>> > +                alloc_required = true;
>> > +
>> > +        /*
>> > +         * If the subregion is already ISSUED state,
>> > +         * a specific event (e.g., GC or wear-leveling, etc.) occurs in
>> > +         * the device and HPB response for map loading is received.
>> > +         * In this case, after finishing the HPB_READ_BUFFER,
>> > +         * the next HPB_READ_BUFFER is performed again to obtain the latest
>> > +         * map data.
>> > +         */
>> > +        if (srgn->srgn_state == HPB_SRGN_ISSUED)
>> > +                goto unlock_out;
>> > +
>> > +        srgn->srgn_state = HPB_SRGN_ISSUED;
>> > +        spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
>> > +
>> > +        if (alloc_required) {
>> > +                if (srgn->mctx) {
>> 
>> Can this really happen?
>> 
>> alloc_required is true if srgn->srgn_state == HPB_SRGN_UNUSED.
>> ufshpb_put_map_ctx() is called and srgn->srgn_state is given
>> HPB_SRGN_UNUSED together in ufshpb_purge_active_subregion().
>> Do I miss anything?
> 
> It is not normal case, but it is for preventing memory leak on abnormal 
> case.
> 
> Thanks,
> Daejun

Abnormal how? Could you please give an example?

Thanks,
Can Guo