Re: [REGRESSION] "split bio_kmalloc from bio_alloc_bioset" causing crash shortly after bootup

From: Christoph Hellwig
Date: Tue Feb 23 2021 - 02:11:40 EST


On Tue, Feb 23, 2021 at 03:51:23AM +0000, Chaitanya Kulkarni wrote:
> Looking at the other call sites do we need something like following ?

> Since __blk_queue_bounce() passes the NULL for the passthru case as a
> bio_set value ?

Well, that is a somewhat odd calling convention. What about the patch below
instead? That being we really need to kill this bouncing code off..


diff --git a/block/bounce.c b/block/bounce.c
index fc55314aa4269a..789fbcacb1e92a 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -214,9 +214,9 @@ static void bounce_end_io_read_isa(struct bio *bio)
__bounce_end_io_read(bio, &isa_page_pool);
}

-static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
- struct bio_set *bs)
+static struct bio *bounce_clone_bio(struct bio *bio_src, bool passthrough)
{
+ unsigned int nr_vecs = bio_segments(bio_src);
struct bvec_iter iter;
struct bio_vec bv;
struct bio *bio;
@@ -242,8 +242,10 @@ static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
* asking for trouble and would force extra work on
* __bio_clone_fast() anyways.
*/
-
- bio = bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);
+ if (passthrough)
+ bio = bio_kmalloc(GFP_NOIO, nr_vecs);
+ else
+ bio = bio_alloc_bioset(GFP_NOIO, nr_vecs, &bounce_bio_set);
if (!bio)
return NULL;
bio->bi_bdev = bio_src->bi_bdev;
@@ -269,11 +271,11 @@ static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,
break;
}

- if (bio_crypt_clone(bio, bio_src, gfp_mask) < 0)
+ if (bio_crypt_clone(bio, bio_src, GFP_NOIO) < 0)
goto err_put;

if (bio_integrity(bio_src) &&
- bio_integrity_clone(bio, bio_src, gfp_mask) < 0)
+ bio_integrity_clone(bio, bio_src, GFP_NOIO) < 0)
goto err_put;

bio_clone_blkg_association(bio, bio_src);
@@ -313,8 +315,7 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
submit_bio_noacct(*bio_orig);
*bio_orig = bio;
}
- bio = bounce_clone_bio(*bio_orig, GFP_NOIO, passthrough ? NULL :
- &bounce_bio_set);
+ bio = bounce_clone_bio(*bio_orig, passthrough);

/*
* Bvec table can't be updated by bio_for_each_segment_all(),