Re: [REGRESSION] "split bio_kmalloc from bio_alloc_bioset" causing crash shortly after bootup
From: Christoph Hellwig <hch@lst.de>
Date: 2021-02-23 07:24:01
Also in:
lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
On Tue, Feb 23, 2021 at 08:04:08AM +0100, Christoph Hellwig wrote:
The problem is that the blk-crypto fallback code calls bio_split with a NULL bioset. That was aready broken before, as the mempool needed to guarantee forward progress was missing, but is not fatal. Satya, can you look into adding a mempool that can guarantees forward progress here?
Something like this would be the minimum viable fix:
diff --git a/block/blk-crypto-fallback.c b/block/blk-crypto-fallback.c
index e8327c50d7c9f4..c176b7af56a7a5 100644
--- a/block/blk-crypto-fallback.c
+++ b/block/blk-crypto-fallback.c@@ -80,6 +80,7 @@ static struct blk_crypto_keyslot { static struct blk_keyslot_manager blk_crypto_ksm; static struct workqueue_struct *blk_crypto_wq; static mempool_t *blk_crypto_bounce_page_pool; +static struct bio_set crypto_bio_split; /* * This is the key we set when evicting a keyslot. This *should* be the all 0's
@@ -224,7 +225,8 @@ static bool blk_crypto_split_bio_if_needed(struct bio **bio_ptr) if (num_sectors < bio_sectors(bio)) { struct bio *split_bio; - split_bio = bio_split(bio, num_sectors, GFP_NOIO, NULL); + split_bio = bio_split(bio, num_sectors, GFP_NOIO, + &crypto_bio_split); if (!split_bio) { bio->bi_status = BLK_STS_RESOURCE; return false;
@@ -538,9 +540,13 @@ static int blk_crypto_fallback_init(void) prandom_bytes(blank_key, BLK_CRYPTO_MAX_KEY_SIZE); - err = blk_ksm_init(&blk_crypto_ksm, blk_crypto_num_keyslots); + err = bioset_init(&crypto_bio_split, 64, 0, 0); if (err) goto out; + + err = blk_ksm_init(&blk_crypto_ksm, blk_crypto_num_keyslots); + if (err) + goto fail_free_bioset; err = -ENOMEM; blk_crypto_ksm.ksm_ll_ops = blk_crypto_ksm_ll_ops;
@@ -591,6 +597,8 @@ static int blk_crypto_fallback_init(void) destroy_workqueue(blk_crypto_wq); fail_free_ksm: blk_ksm_destroy(&blk_crypto_ksm); +fail_free_bioset: + bioset_exit(&crypto_bio_split); out: return err; }