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

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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@xxxxxx>
---
  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@xxxxxxxxxxxxxx/
--
nvpublic




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