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

Christoph Hellwig
2024-02-21T05:44:31Z

On Tue, Feb 20, 2024 at 11:01:05PM +0100, Geert Uytterhoeven wrote:
> Hi Christoph,
>
> On Thu, Feb 15, 2024 at 9:16 AM Christoph Hellwig <hch@lst.de> 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>
>
> Thanks for your patch, which is now commit 616f876617927732 ("mmc: pass
> queue_limits to blk_mq_alloc_disk") in block/for-next.
>
> I have bisected the following failure on White-Hawk (also seen on
> other R-Car Gen3/4 systems) to this commit:
>
> renesas_sdhi_internal_dmac ee140000.mmc: mmc0 base at
> 0x00000000ee140000, max clock rate 200 MHz
> mmc0: new HS400 MMC card at address 0001
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 20 at block/blk-settings.c:202
> blk_validate_limits+0x12c/0x1e0

This is:

if (lim->virt_boundary_mask) {
if (WARN_ON_ONCE(lim->max_segment_size &&
lim->max_segment_size != UINT_MAX))
return -EINVAL;

so we end up here with both a virt_boundary_mask and a
max_segment_size set, which is rather bogus. I think the
problem is the order of check in the core blk_validate_limits
that artificially causes this. Can you try this patch?

diff --git a/block/blk-settings.c b/block/blk-settings.c
index c4406aacc0efc6..2120b6f9fef8ea 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -182,16 +182,6 @@ static int blk_validate_limits(struct queue_limits *lim)
if (WARN_ON_ONCE(lim->seg_boundary_mask < PAGE_SIZE - 1))
return -EINVAL;

- /*
- * The maximum segment size has an odd historic 64k default that
- * drivers probably should override. Just like the I/O size we
- * require drivers to at least handle a full page per segment.
- */
- if (!lim->max_segment_size)
- lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
- if (WARN_ON_ONCE(lim->max_segment_size < PAGE_SIZE))
- return -EINVAL;
-
/*
* Devices that require a virtual boundary do not support scatter/gather
* I/O natively, but instead require a descriptor list entry for each
@@ -203,6 +193,16 @@ static int blk_validate_limits(struct queue_limits *lim)
lim->max_segment_size != UINT_MAX))
return -EINVAL;
lim->max_segment_size = UINT_MAX;
+ } else {
+ /*
+ * The maximum segment size has an odd historic 64k default that
+ * drivers probably should override. Just like the I/O size we
+ * require drivers to at least handle a full page per segment.
+ */
+ if (!lim->max_segment_size)
+ lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
+ if (WARN_ON_ONCE(lim->max_segment_size < PAGE_SIZE))
+ return -EINVAL;
}

/*