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SubjectRe: [REGRESSION] "split bio_kmalloc from bio_alloc_bioset" causing crash shortly after bootup
On Mon, Feb 22, 2021 at 7:39 PM Chaitanya Kulkarni
<Chaitanya.Kulkarni@wdc.com> wrote:
>
> On 2/22/21 19:07, John Stultz wrote:
> > [ 34.784901] ueventd: LoadWithAliases was unable to load platform:regulatory
> > [ 34.785313] bio_alloc_bioset+0x14/0x230
> > [ 34.796189] bio_clone_fast+0x28/0x80
> > [ 34.799848] bio_split+0x50/0xd0
> > [ 34.803072] blk_crypto_fallback_encrypt_bio+0x2ec/0x5e8
> > [ 34.808384] blk_crypto_fallback_bio_prep+0xfc/0x140
> > [ 34.813345] __blk_crypto_bio_prep+0x13c/0x150
> > [ 34.817784] submit_bio_noacct+0x3c0/0x548
> > [ 34.821880] submit_bio+0x48/0x200
> > [ 34.825278] ext4_io_submit+0x50/0x68
> > [ 34.828939] ext4_writepages+0x558/0xca8
> > [ 34.832860] do_writepages+0x58/0x108
> > [ 34.836522] __writeback_single_inode+0x44/0x510
> > [ 34.841137] writeback_sb_inodes+0x1e0/0x4a8
> > [ 34.845404] __writeback_inodes_wb+0x78/0xe8
> > [ 34.849670] wb_writeback+0x274/0x3e8
> > [ 34.853328] wb_workfn+0x308/0x5f0
> > [ 34.856726] process_one_work+0x1ec/0x4d0
> > [ 34.860734] worker_thread+0x44/0x478
> > [ 34.864392] kthread+0x140/0x150
> > [ 34.867618] ret_from_fork+0x10/0x30
> > [ 34.871197] Code: a9ba7bfd 910003fd f9000bf3 7900bfa1 (f9403441)
> > [ 34.877289] ---[ end trace e6c2a3ab108278f0 ]---
> > [ 34.893636] Kernel panic - not syncing: Oops: Fatal exception
> >
>
> If you have time then until you get the reply from others, can you try
> following patch ?
>
> diff --git a/block/bio.c b/block/bio.c
> index a1c4d2900c7a..9976400ec66a 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -663,7 +663,10 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t
> gfp_mask, struct bio_set *bs)
> {
> struct bio *b;
>
> - b = bio_alloc_bioset(gfp_mask, 0, bs);
> + if (bs)
> + b = bio_alloc_bioset(gfp_mask, 0, bs);
> + else
> + b = bio_kmalloc(gfp_mask, 0);
> if (!b)
> return NULL;
>
> P.S.This is purely based on the code inspection and it may not solve your
> issue. Proceed with the caution as it may *break* your system.

So with an initial quick test, this patch (along with the follow-on
one you sent) seems to avoid the issue.

I'm wondering if given there are multiple call sites, that in
bio_alloc_bioset() would something like the following make more sense?
(apologies, copy pasted so this is whitespace corrupted)
thanks
-john

diff --git a/block/bio.c b/block/bio.c
index a1c4d2900c7a..391d5cde79fc 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -402,6 +402,9 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask,
unsigned short nr_iovecs,
struct bio *bio;
void *p;

+ if(!bs)
+ return bio_kmalloc(gfp_mask, 0);
+
/* should not use nobvec bioset for nr_iovecs > 0 */
if (WARN_ON_ONCE(!mempool_initialized(&bs->bvec_pool) && nr_iovecs > 0))
return NULL;
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