On Thu, Apr 08, 2021 at 02:45:06PM -0700, Guenter Roeck wrote:

On Wed, Mar 31, 2021 at 09:30:01AM +0200, Christoph Hellwig wrote:

quoted

Instead of overloading the passthrough fast path with the deprecated
block layer bounce buffering let the users that combine an old
undermaintained driver with a highmem system pay the price by always
falling back to copies in that case.

Hmm, that price is pretty high. When trying to boot sh images from usb,
it results in a traceback, followed by an i/o error, and the drive
fails to open.

That's just because this warning is completely bogus, sorry.

Does this patch fix the boot for you?

diff --git a/block/blk-map.c b/block/blk-map.c
index dac78376acc899..3743158ddaeb76 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c

@@ -485,9 +485,6 @@ int blk_rq_append_bio(struct request *rq, struct bio *bio)
 	struct bio_vec bv;
 	unsigned int nr_segs = 0;
 
-	if (WARN_ON_ONCE(rq->q->limits.bounce != BLK_BOUNCE_NONE))
-		return -EINVAL;
-
 	bio_for_each_bvec(bv, bio, iter)
 		nr_segs++;