[PATCH v3 2/2] dm crypt: use GFP_ATOMIC when allocating crypto requests from softirq

From: Ignat Korchagin
Date: Mon Jan 04 2021 - 10:02:05 EST

Commit 39d42fa96ba1b7d2544db3f8ed5da8fb0d5cb877 made it possible for some code
paths in dm-crypt to be executed in softirq context, when the underlying driver
processes IO requests in interrupt/softirq context.

In this case sometimes when allocating a new crypto request we may get a
stacktrace like below:

[ 210.103008][ C0] BUG: sleeping function called from invalid context at mm/mempool.c:381
[ 210.104746][ C0] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2602, name: fio
[ 210.106599][ C0] CPU: 0 PID: 2602 Comm: fio Tainted: G W 5.10.0+ #50
[ 210.108331][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
[ 210.110212][ C0] Call Trace:
[ 210.110921][ C0] <IRQ>
[ 210.111527][ C0] dump_stack+0x7d/0xa3
[ 210.112411][ C0] ___might_sleep.cold+0x122/0x151
[ 210.113527][ C0] mempool_alloc+0x16b/0x2f0
[ 210.114524][ C0] ? __queue_work+0x515/0xde0
[ 210.115553][ C0] ? mempool_resize+0x700/0x700
[ 210.116586][ C0] ? crypt_endio+0x91/0x180
[ 210.117479][ C0] ? blk_update_request+0x757/0x1150
[ 210.118513][ C0] ? blk_mq_end_request+0x4b/0x480
[ 210.119572][ C0] ? blk_done_softirq+0x21d/0x340
[ 210.120628][ C0] ? __do_softirq+0x190/0x611
[ 210.121626][ C0] crypt_convert+0x29f9/0x4c00
[ 210.122668][ C0] ? _raw_spin_lock_irqsave+0x87/0xe0
[ 210.123824][ C0] ? kasan_set_track+0x1c/0x30
[ 210.124858][ C0] ? crypt_iv_tcw_ctr+0x4a0/0x4a0
[ 210.125930][ C0] ? kmem_cache_free+0x104/0x470
[ 210.126973][ C0] ? crypt_endio+0x91/0x180
[ 210.127947][ C0] kcryptd_crypt_read_convert+0x30e/0x420
[ 210.129165][ C0] blk_update_request+0x757/0x1150
[ 210.130231][ C0] blk_mq_end_request+0x4b/0x480
[ 210.131294][ C0] blk_done_softirq+0x21d/0x340
[ 210.132332][ C0] ? _raw_spin_lock+0x81/0xd0
[ 210.133289][ C0] ? blk_mq_stop_hw_queue+0x30/0x30
[ 210.134399][ C0] ? _raw_read_lock_irq+0x40/0x40
[ 210.135458][ C0] __do_softirq+0x190/0x611
[ 210.136409][ C0] ? handle_edge_irq+0x221/0xb60
[ 210.137447][ C0] asm_call_irq_on_stack+0x12/0x20
[ 210.138507][ C0] </IRQ>
[ 210.139118][ C0] do_softirq_own_stack+0x37/0x40
[ 210.140191][ C0] irq_exit_rcu+0x110/0x1b0
[ 210.141151][ C0] common_interrupt+0x74/0x120
[ 210.142171][ C0] asm_common_interrupt+0x1e/0x40
[ 210.143206][ C0] RIP: 0010:_aesni_enc1+0x65/0xb0
[ 210.144313][ C0] Code: 38 dc c2 41 0f 28 52 d0 66 0f 38 dc c2 41 0f 28 52 e0 66 0f 38 dc c2 41 0f 28 52 f0 66 0f 38 dc c2 41 0f 28 12 66 0f 38 dc c2 <41> 0f 28 52 10 66 0f 38 dc c2 41 0f 28 52 20 66 0f 38 dc c2 41 0f
[ 210.148542][ C0] RSP: 0018:ffff88810dbe6db0 EFLAGS: 00000286
[ 210.149842][ C0] RAX: ffffffff9a90cdc0 RBX: 0000000000000000 RCX: 0000000000000200
[ 210.151576][ C0] RDX: ffff888101e5f240 RSI: ffff888101e5f240 RDI: ffff8881111b5020
[ 210.153339][ C0] RBP: ffff88810dbe6e20 R08: 0000000000000000 R09: 0000000000000020
[ 210.155063][ C0] R10: ffff8881111b5090 R11: 1ffff11021b7cdcc R12: ffffffff9e87cd40
[ 210.156791][ C0] R13: ffff8881111b5210 R14: ffff888101e5f0d8 R15: 0000000000000000
[ 210.158497][ C0] ? aesni_set_key+0x1e0/0x1e0
[ 210.159523][ C0] ? aesni_enc+0xf/0x20
[ 210.160408][ C0] ? glue_xts_req_128bit+0x181/0x6f0
[ 210.161571][ C0] ? aesni_set_key+0x1e0/0x1e0
[ 210.162560][ C0] ? glue_ctr_req_128bit+0x630/0x630
[ 210.163706][ C0] ? kasan_save_stack+0x37/0x50
[ 210.164761][ C0] ? kasan_save_stack+0x20/0x50
[ 210.165786][ C0] ? get_page_from_freelist+0x2052/0x36a0
[ 210.167024][ C0] ? __blkdev_direct_IO_simple+0x43b/0x7e0
[ 210.168288][ C0] ? blkdev_direct_IO+0xd16/0x1020
[ 210.169396][ C0] ? generic_file_direct_write+0x1a3/0x480
[ 210.170648][ C0] ? __generic_file_write_iter+0x1d9/0x530
[ 210.171882][ C0] ? blkdev_write_iter+0x20d/0x3e0
[ 210.172954][ C0] ? vfs_write+0x524/0x770
[ 210.173889][ C0] ? do_syscall_64+0x33/0x40
[ 210.174859][ C0] ? __zone_watermark_ok+0x340/0x340
[ 210.175977][ C0] ? crypt_convert+0x28b6/0x4c00
[ 210.177079][ C0] ? mempool_alloc+0x107/0x2f0
[ 210.178096][ C0] ? crypt_iv_tcw_ctr+0x4a0/0x4a0
[ 210.179193][ C0] ? bio_add_page+0x111/0x170
[ 210.180251][ C0] ? __bio_try_merge_page+0x480/0x480
[ 210.181446][ C0] ? bio_associate_blkg+0x6d/0x100
[ 210.182558][ C0] ? kcryptd_crypt_write_convert+0x5ea/0x980
[ 210.183852][ C0] ? crypt_map+0x5bf/0xc80
[ 210.184838][ C0] ? bio_clone_blkg_association+0x10e/0x2c0
[ 210.186125][ C0] ? __map_bio.isra.0+0x109/0x3f0
[ 210.187204][ C0] ? __split_and_process_non_flush+0x7f9/0xc50
[ 210.188560][ C0] ? __send_empty_flush+0x2d0/0x2d0
[ 210.189697][ C0] ? __part_start_io_acct+0x70/0x2d0
[ 210.190842][ C0] ? dm_submit_bio+0x4d8/0xe40
[ 210.191845][ C0] ? __split_and_process_non_flush+0xc50/0xc50
[ 210.193201][ C0] ? submit_bio_noacct+0x2b9/0xe50
[ 210.194313][ C0] ? blk_queue_enter+0x6d0/0x6d0
[ 210.195372][ C0] ? __bio_add_page+0x246/0x3d0
[ 210.196418][ C0] ? bio_iov_iter_get_pages+0x7dd/0xbe0
[ 210.197611][ C0] ? submit_bio+0xe2/0x460
[ 210.198481][ C0] ? submit_bio_noacct+0xe50/0xe50
[ 210.199496][ C0] ? free_unref_page_commit.constprop.0+0x130/0x330
[ 210.200825][ C0] ? __blkdev_direct_IO_simple+0x43b/0x7e0
[ 210.202050][ C0] ? bd_link_disk_holder+0x690/0x690
[ 210.203239][ C0] ? put_pages_list+0x210/0x210
[ 210.204341][ C0] ? scan_shadow_nodes+0xb0/0xb0
[ 210.205472][ C0] ? _raw_write_lock_irqsave+0xe0/0xe0
[ 210.206698][ C0] ? bd_may_claim+0xc0/0xc0
[ 210.207715][ C0] ? zero_user_segments.constprop.0+0x2e0/0x2e0
[ 210.209092][ C0] ? blkdev_direct_IO+0xd16/0x1020
[ 210.210200][ C0] ? pagevec_lookup_range_tag+0x28/0x60
[ 210.211416][ C0] ? __filemap_fdatawait_range+0xc4/0x1f0
[ 210.212669][ C0] ? page_cache_next_miss+0x1e0/0x1e0
[ 210.213842][ C0] ? generic_file_buffered_read+0x520/0x9e0
[ 210.215128][ C0] ? delete_from_page_cache_batch+0x850/0x850
[ 210.216470][ C0] ? bd_abort_claiming+0xd0/0xd0
[ 210.217531][ C0] ? file_remove_privs+0x74/0x430
[ 210.218589][ C0] ? filemap_check_errors+0x50/0xe0
[ 210.219705][ C0] ? generic_file_direct_write+0x1a3/0x480
[ 210.220979][ C0] ? __generic_file_write_iter+0x1d9/0x530
[ 210.222238][ C0] ? blkdev_write_iter+0x20d/0x3e0
[ 210.223328][ C0] ? bd_unlink_disk_holder+0x360/0x360
[ 210.224464][ C0] ? new_sync_write+0x37b/0x620
[ 210.225511][ C0] ? new_sync_read+0x610/0x610
[ 210.226539][ C0] ? _cond_resched+0x17/0x80
[ 210.227539][ C0] ? inode_security+0x58/0x100
[ 210.228582][ C0] ? security_file_permission+0x54/0x450
[ 210.229796][ C0] ? vfs_write+0x524/0x770
[ 210.230758][ C0] ? __x64_sys_pwrite64+0x197/0x1f0
[ 210.231890][ C0] ? vfs_write+0x770/0x770
[ 210.232869][ C0] ? do_syscall_64+0x33/0x40
[ 210.233839][ C0] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fix this by allocating crypto requests with GFP_ATOMIC mask in interrupt context

Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workqueues")
Reported-by: Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v5.9+
Signed-off-by: Ignat Korchagin <ignat@xxxxxxxxxxxxxx>
---
drivers/md/dm-crypt.c | 35 +++++++++++++++++++++++++----------
1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index a3326dadfd4d..1f471dd75144 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1454,13 +1454,16 @@ static int crypt_convert_block_skcipher(struct crypt_config *cc,
static void kcryptd_async_done(struct crypto_async_request *async_req,
int error);

-static void crypt_alloc_req_skcipher(struct crypt_config *cc,
+static int crypt_alloc_req_skcipher(struct crypt_config *cc,
struct convert_context *ctx)
{
unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1);

- if (!ctx->r.req)
- ctx->r.req = mempool_alloc(&cc->req_pool, GFP_NOIO);
+ if (!ctx->r.req) {
+ ctx->r.req = mempool_alloc(&cc->req_pool, in_interrupt() ? GFP_ATOMIC : GFP_NOIO);
+ if (!ctx->r.req)
+ return -ENOMEM;
+ }

skcipher_request_set_tfm(ctx->r.req, cc->cipher_tfm.tfms[key_index]);

@@ -1471,13 +1474,18 @@ static void crypt_alloc_req_skcipher(struct crypt_config *cc,
skcipher_request_set_callback(ctx->r.req,
CRYPTO_TFM_REQ_MAY_BACKLOG,
kcryptd_async_done, dmreq_of_req(cc, ctx->r.req));
+
+ return 0;
}

-static void crypt_alloc_req_aead(struct crypt_config *cc,
+static int crypt_alloc_req_aead(struct crypt_config *cc,
struct convert_context *ctx)
{
- if (!ctx->r.req_aead)
- ctx->r.req_aead = mempool_alloc(&cc->req_pool, GFP_NOIO);
+ if (!ctx->r.req) {
+ ctx->r.req = mempool_alloc(&cc->req_pool, in_interrupt() ? GFP_ATOMIC : GFP_NOIO);
+ if (!ctx->r.req)
+ return -ENOMEM;
+ }

aead_request_set_tfm(ctx->r.req_aead, cc->cipher_tfm.tfms_aead[0]);

@@ -1488,15 +1496,17 @@ static void crypt_alloc_req_aead(struct crypt_config *cc,
aead_request_set_callback(ctx->r.req_aead,
CRYPTO_TFM_REQ_MAY_BACKLOG,
kcryptd_async_done, dmreq_of_req(cc, ctx->r.req_aead));
+
+ return 0;
}

-static void crypt_alloc_req(struct crypt_config *cc,
+static int crypt_alloc_req(struct crypt_config *cc,
struct convert_context *ctx)
{
if (crypt_integrity_aead(cc))
- crypt_alloc_req_aead(cc, ctx);
+ return crypt_alloc_req_aead(cc, ctx);
else
- crypt_alloc_req_skcipher(cc, ctx);
+ return crypt_alloc_req_skcipher(cc, ctx);
}

static void crypt_free_req_skcipher(struct crypt_config *cc,
@@ -1545,7 +1555,12 @@ static blk_status_t crypt_convert(struct crypt_config *cc,

while (ctx->iter_in.bi_size && ctx->iter_out.bi_size) {

- crypt_alloc_req(cc, ctx);
+ r = crypt_alloc_req(cc, ctx);
+ if (r) {
+ complete(&ctx->restart);
+ return BLK_STS_DEV_RESOURCE;
+ }
+
atomic_inc(&ctx->cc_pending);

if (crypt_integrity_aead(cc))
--
2.20.1