From 5ac0da68eae1e170888bd366f077ef484c2a6403 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 12 Dec 2018 09:18:11 -0700 Subject: [PATCH] nvme: provide fallback for discard alloc failure [ Upstream commit cb5b7262b011cfb793519bf97e54dff5282da23c ] When boxes are run near (or to) OOM, we have a problem with the discard page allocation in nvme. If we fail allocating the special page, we return busy, and it'll get retried. But since ordering is honored for dispatch requests, we can keep retrying this same IO and failing. Behind that IO could be requests that want to free memory, but they never get the chance. Allocate a fixed discard page per controller for a safe fallback, and use that if the initial allocation fails. Signed-off-by: Jens Axboe Reviewed-by: Keith Busch Reviewed-by: Sagi Grimberg Signed-off-by: Christoph Hellwig Signed-off-by: Sasha Levin --- drivers/nvme/host/core.c | 41 ++++++++++++++++++++++++++++++++++------ drivers/nvme/host/nvme.h | 3 +++ 2 files changed, 38 insertions(+), 6 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 44da9fe5b27b..250ccf3108e9 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -551,9 +551,19 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req, struct nvme_dsm_range *range; struct bio *bio; - range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC); - if (!range) - return BLK_STS_RESOURCE; + range = kmalloc_array(segments, sizeof(*range), + GFP_ATOMIC | __GFP_NOWARN); + if (!range) { + /* + * If we fail allocation our range, fallback to the controller + * discard page. If that's also busy, it's safe to return + * busy, as we know we can make progress once that's freed. + */ + if (test_and_set_bit_lock(0, &ns->ctrl->discard_page_busy)) + return BLK_STS_RESOURCE; + + range = page_address(ns->ctrl->discard_page); + } __rq_for_each_bio(bio, req) { u64 slba = nvme_block_nr(ns, bio->bi_iter.bi_sector); @@ -568,7 +578,10 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req, } if (WARN_ON_ONCE(n != segments)) { - kfree(range); + if (virt_to_page(range) == ns->ctrl->discard_page) + clear_bit_unlock(0, &ns->ctrl->discard_page_busy); + else + kfree(range); return BLK_STS_IOERR; } @@ -653,8 +666,13 @@ void nvme_cleanup_cmd(struct request *req) blk_rq_bytes(req) >> ns->lba_shift); } if (req->rq_flags & RQF_SPECIAL_PAYLOAD) { - kfree(page_address(req->special_vec.bv_page) + - req->special_vec.bv_offset); + struct nvme_ns *ns = req->rq_disk->private_data; + struct page *page = req->special_vec.bv_page; + + if (page == ns->ctrl->discard_page) + clear_bit_unlock(0, &ns->ctrl->discard_page_busy); + else + kfree(page_address(page) + req->special_vec.bv_offset); } } EXPORT_SYMBOL_GPL(nvme_cleanup_cmd); @@ -3551,6 +3569,7 @@ static void nvme_free_ctrl(struct device *dev) ida_simple_remove(&nvme_instance_ida, ctrl->instance); kfree(ctrl->effects); nvme_mpath_uninit(ctrl); + kfree(ctrl->discard_page); if (subsys) { mutex_lock(&subsys->lock); @@ -3592,6 +3611,14 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev, memset(&ctrl->ka_cmd, 0, sizeof(ctrl->ka_cmd)); ctrl->ka_cmd.common.opcode = nvme_admin_keep_alive; + BUILD_BUG_ON(NVME_DSM_MAX_RANGES * sizeof(struct nvme_dsm_range) > + PAGE_SIZE); + ctrl->discard_page = alloc_page(GFP_KERNEL); + if (!ctrl->discard_page) { + ret = -ENOMEM; + goto out; + } + ret = ida_simple_get(&nvme_instance_ida, 0, 0, GFP_KERNEL); if (ret < 0) goto out; @@ -3629,6 +3656,8 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev, out_release_instance: ida_simple_remove(&nvme_instance_ida, ctrl->instance); out: + if (ctrl->discard_page) + __free_page(ctrl->discard_page); return ret; } EXPORT_SYMBOL_GPL(nvme_init_ctrl); diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 2653e1f4196d..cc4273f11989 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -238,6 +238,9 @@ struct nvme_ctrl { u16 maxcmd; int nr_reconnects; struct nvmf_ctrl_options *opts; + + struct page *discard_page; + unsigned long discard_page_busy; }; struct nvme_subsystem { -- GitLab