3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Mikulas Patocka mpatocka@redhat.com
commit 432061b3da64e488be3403124a72a9250bbe96d4 upstream.
There's a XFS on dm-crypt deadlock, recursing back to itself due to the crypto subsystems use of GFP_KERNEL, reported here: https://bugzilla.kernel.org/show_bug.cgi?id=200835
* dm-crypt calls crypt_convert in xts mode * init_crypt from xts.c calls kmalloc(GFP_KERNEL) * kmalloc(GFP_KERNEL) recurses into the XFS filesystem, the filesystem tries to submit some bios and wait for them, causing a deadlock
Fix this by updating both the DM crypt and integrity targets to no longer use the CRYPTO_TFM_REQ_MAY_SLEEP flag, which will change the crypto allocations from GFP_KERNEL to GFP_ATOMIC, therefore they can't recurse into a filesystem. A GFP_ATOMIC allocation can fail, but init_crypt() in xts.c handles the allocation failure gracefully - it will fall back to preallocated buffer if the allocation fails.
The crypto API maintainer says that the crypto API only needs to allocate memory when dealing with unaligned buffers and therefore turning CRYPTO_TFM_REQ_MAY_SLEEP off is safe (see this discussion: https://www.redhat.com/archives/dm-devel/2018-August/msg00195.html )
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com [bwh: Backported to 3.16: - Drop change to crypt_alloc_req_aead() in dm-crypt - Drop changes to dm-integrity - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -262,7 +262,7 @@ static int crypt_iv_essiv_init(struct cr
sg_init_one(&sg, cc->key, cc->key_size); desc.tfm = essiv->hash_tfm; - desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + desc.flags = 0;
err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt); if (err) @@ -533,7 +533,7 @@ static int crypt_iv_lmk_one(struct crypt int i, r;
sdesc.desc.tfm = lmk->hash_tfm; - sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + sdesc.desc.flags = 0;
r = crypto_shash_init(&sdesc.desc); if (r) @@ -690,7 +690,7 @@ static int crypt_iv_tcw_whitening(struct
/* calculate crc32 for every 32bit part and xor it */ sdesc.desc.tfm = tcw->crc32_tfm; - sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; + sdesc.desc.flags = 0; for (i = 0; i < 4; i++) { r = crypto_shash_init(&sdesc.desc); if (r) @@ -891,7 +891,7 @@ static void crypt_alloc_req(struct crypt
ablkcipher_request_set_tfm(ctx->req, cc->tfms[key_index]); ablkcipher_request_set_callback(ctx->req, - CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + CRYPTO_TFM_REQ_MAY_BACKLOG, kcryptd_async_done, dmreq_of_req(cc, ctx->req)); }