Re: [PATCH 17/17] mmc: pass queue_limits to blk_mq_alloc_disk

Jon Hunter
2024-06-27T09:43:37Z

Hi Christoph,

On 15/02/2024 07:03, Christoph Hellwig wrote:
> Pass the queue limit set at initialization time directly to
> blk_mq_alloc_disk instead of updating it right after the allocation.
>
> This requires refactoring the code a bit so that what was mmc_setup_queue
> before also allocates the gendisk now and actually sets all limits.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/mmc/core/queue.c | 97 +++++++++++++++++++++-------------------
> 1 file changed, 52 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index 67ad186d132a69..2ae60d208cdf1e 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -174,8 +174,8 @@ static struct scatterlist *mmc_alloc_sg(unsigned short sg_len, gfp_t gfp)
> return sg;
> }
>
> -static void mmc_queue_setup_discard(struct request_queue *q,
> - struct mmc_card *card)
> +static void mmc_queue_setup_discard(struct mmc_card *card,
> + struct queue_limits *lim)
> {
> unsigned max_discard;
>
> @@ -183,15 +183,17 @@ static void mmc_queue_setup_discard(struct request_queue *q,
> if (!max_discard)
> return;
>
> - blk_queue_max_discard_sectors(q, max_discard);
> - q->limits.discard_granularity = card->pref_erase << 9;
> - /* granularity must not be greater than max. discard */
> - if (card->pref_erase > max_discard)
> - q->limits.discard_granularity = SECTOR_SIZE;
> + lim->max_hw_discard_sectors = max_discard;
> if (mmc_can_secure_erase_trim(card))
> - blk_queue_max_secure_erase_sectors(q, max_discard);
> + lim->max_secure_erase_sectors = max_discard;
> if (mmc_can_trim(card) && card->erased_byte == 0)
> - blk_queue_max_write_zeroes_sectors(q, max_discard);
> + lim->max_write_zeroes_sectors = max_discard;
> +
> + /* granularity must not be greater than max. discard */
> + if (card->pref_erase > max_discard)
> + lim->discard_granularity = SECTOR_SIZE;
> + else
> + lim->discard_granularity = card->pref_erase << 9;
> }
>
> static unsigned short mmc_get_max_segments(struct mmc_host *host)
> @@ -341,40 +343,53 @@ static const struct blk_mq_ops mmc_mq_ops = {
> .timeout = mmc_mq_timed_out,
> };
>
> -static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
> +static struct gendisk *mmc_alloc_disk(struct mmc_queue *mq,
> + struct mmc_card *card)
> {
> struct mmc_host *host = card->host;
> - unsigned block_size = 512;
> + struct queue_limits lim = { };
> + struct gendisk *disk;
>
> - blk_queue_flag_set(QUEUE_FLAG_NONROT, mq->queue);
> - blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue);
> if (mmc_can_erase(card))
> - mmc_queue_setup_discard(mq->queue, card);
> + mmc_queue_setup_discard(card, &lim);
>
> if (!mmc_dev(host)->dma_mask || !*mmc_dev(host)->dma_mask)
> - blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH);
> - blk_queue_max_hw_sectors(mq->queue,
> - min(host->max_blk_count, host->max_req_size / 512));
> - if (host->can_dma_map_merge)
> - WARN(!blk_queue_can_use_dma_map_merging(mq->queue,
> - mmc_dev(host)),
> - "merging was advertised but not possible");
> - blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));
> -
> - if (mmc_card_mmc(card) && card->ext_csd.data_sector_size) {
> - block_size = card->ext_csd.data_sector_size;
> - WARN_ON(block_size != 512 && block_size != 4096);
> - }
> + lim.bounce = BLK_BOUNCE_HIGH;
> +
> + lim.max_hw_sectors = min(host->max_blk_count, host->max_req_size / 512);
> +
> + if (mmc_card_mmc(card) && card->ext_csd.data_sector_size)
> + lim.logical_block_size = card->ext_csd.data_sector_size;
> + else
> + lim.logical_block_size = 512;
> +
> + WARN_ON_ONCE(lim.logical_block_size != 512 &&
> + lim.logical_block_size != 4096);
>
> - blk_queue_logical_block_size(mq->queue, block_size);
> /*
> - * After blk_queue_can_use_dma_map_merging() was called with succeed,
> - * since it calls blk_queue_virt_boundary(), the mmc should not call
> - * both blk_queue_max_segment_size().
> + * Setting a virt_boundary implicity sets a max_segment_size, so try
> + * to set the hardware one here.
> */
> - if (!host->can_dma_map_merge)
> - blk_queue_max_segment_size(mq->queue,
> - round_down(host->max_seg_size, block_size));
> + if (host->can_dma_map_merge) {
> + lim.virt_boundary_mask = dma_get_merge_boundary(mmc_dev(host));
> + lim.max_segments = MMC_DMA_MAP_MERGE_SEGMENTS;
> + } else {
> + lim.max_segment_size =
> + round_down(host->max_seg_size, lim.logical_block_size);
> + lim.max_segments = host->max_segs;
> + }
> +
> + disk = blk_mq_alloc_disk(&mq->tag_set, &lim, mq);
> + if (IS_ERR(disk))
> + return disk;
> + mq->queue = disk->queue;
> +
> + if (mmc_host_is_spi(host) && host->use_spi_crc)
> + blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, mq->queue);
> + blk_queue_rq_timeout(mq->queue, 60 * HZ);
> +
> + blk_queue_flag_set(QUEUE_FLAG_NONROT, mq->queue);
> + blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue);
>
> dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
>
> @@ -386,6 +401,7 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
> init_waitqueue_head(&mq->wait);
>
> mmc_crypto_setup_queue(mq->queue, host);
> + return disk;
> }
>
> static inline bool mmc_merge_capable(struct mmc_host *host)
> @@ -447,18 +463,9 @@ struct gendisk *mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
> return ERR_PTR(ret);
>
>
> - disk = blk_mq_alloc_disk(&mq->tag_set, NULL, mq);
> - if (IS_ERR(disk)) {
> + disk = mmc_alloc_disk(mq, card);
> + if (IS_ERR(disk))
> blk_mq_free_tag_set(&mq->tag_set);
> - return disk;
> - }
> - mq->queue = disk->queue;
> -
> - if (mmc_host_is_spi(host) && host->use_spi_crc)
> - blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, mq->queue);
> - blk_queue_rq_timeout(mq->queue, 60 * HZ);
> -
> - mmc_setup_queue(mq, card);
> return disk;
> }
>

We have just noticed that since Linux v6.9 was released, that if we
build the kernel with 64kB MMU pages, then we see the following WARNING
and probe failure ...

[ 2.828612] ------------[ cut here ]------------
[ 2.829243] WARNING: CPU: 1 PID: 87 at block/blk-settings.c:206 blk_validate_limits+0x1cc/0x234
[ 2.830417] Modules linked in:
[ 2.830963] CPU: 1 PID: 87 Comm: kworker/1:1 Not tainted 6.10.0-rc5 #1
[ 2.831773] Hardware name: NVIDIA Jetson AGX Xavier Developer Kit (DT)
[ 2.832538] Workqueue: events_freezable mmc_rescan
[ 2.833341] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 2.834263] pc : blk_validate_limits+0x1cc/0x234
[ 2.834927] lr : blk_set_default_limits+0x18/0x24
[ 2.835654] sp : ffff800084c4f730
[ 2.836161] x29: ffff800084c4f730 x28: 0000000000000000 x27: 0000000000000000
[ 2.837448] x26: 0000000000000000 x25: ffff000084130008 x24: 00000000ffffffff
[ 2.838607] x23: ffff800082d84000 x22: ffff8000828b79c8 x21: ffff800084c4f8b8
[ 2.839754] x20: 0000000000000008 x19: ffff000084170000 x18: 0000000000000000
[ 2.840831] x17: 00000000900163fe x16: 000000008802ed71 x15: 00000000000003e8
[ 2.842228] x14: 0000000000000002 x13: 00000000000372ef x12: 0000000000002bb0
[ 2.843536] x11: 0000000000000000 x10: 0000000000004400 x9 : 0000000000000000
[ 2.847832] x8 : ffff0000841703a0 x7 : 0000000000000000 x6 : 0000000000000003
[ 2.855075] x5 : ffff000081279e00 x4 : 0000000000000000 x3 : 0000000000000200
[ 2.862140] x2 : 000000000000ffff x1 : 000000000000fe00 x0 : ffff800084c4f8b8
[ 2.869633] Call trace:
[ 2.872055] blk_validate_limits+0x1cc/0x234
[ 2.876278] blk_alloc_queue+0x7c/0x260
[ 2.880038] blk_mq_alloc_queue+0x54/0xbc
[ 2.884504] __blk_mq_alloc_disk+0x20/0x190
[ 2.888266] mmc_alloc_disk+0xbc/0x250
[ 2.892062] mmc_init_queue+0xe8/0x114
[ 2.896091] mmc_blk_alloc_req+0xb4/0x374
[ 2.900237] mmc_blk_probe+0x1d4/0x650
[ 2.904194] mmc_bus_probe+0x20/0x2c
[ 2.907434] really_probe+0xbc/0x2a4
[ 2.911391] __driver_probe_device+0x78/0x12c
[ 2.915627] driver_probe_device+0x40/0x160
[ 2.919587] __device_attach_driver+0xb8/0x134
[ 2.923881] bus_for_each_drv+0x80/0xdc
[ 2.927664] __device_attach+0xa8/0x1b0
[ 2.931578] device_initial_probe+0x14/0x20
[ 2.935845] bus_probe_device+0xa8/0xac
[ 2.939606] device_add+0x590/0x754
[ 2.942864] mmc_add_card+0x238/0x2dc
[ 2.946691] mmc_attach_mmc+0x12c/0x174
[ 2.950494] mmc_rescan+0x27c/0x318
[ 2.954172] process_one_work+0x154/0x298
[ 2.957919] worker_thread+0x304/0x408
[ 2.961931] kthread+0x118/0x11c
[ 2.965187] ret_from_fork+0x10/0x20
[ 2.968835] ---[ end trace 0000000000000000 ]---
[ 2.974440] mmcblk mmc0:0001: probe with driver mmcblk failed with error -22

Bisect points to this commit. This is very similar to the issue Geert
reported [0] but we are still seeing this on the latest mainline with
v6.10-rc5. When building with 4kB MMU pages we don't see this issue
when testing on the same hardware. Let me know if you have any
thoughts?

Thanks
Jon

[0] https://lore.kernel.org/linux-mmc/CAMuHMdWV4nWQHUpBKM2gHWeH9j9c0Di4bhg+F4-SAPEAmZuNSA@mail.gmail.com/
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nvpublic