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@maciej.szmigiero.name Cc: stable@vger.kernel.org # v5.9+ Signed-off-by: Ignat Korchagin ignat@cloudflare.com --- drivers/md/dm-crypt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 5f9f9b3a226d..777b5c71a2f7 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1460,7 +1460,7 @@ static void crypt_alloc_req_skcipher(struct crypt_config *cc, unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1);
if (!ctx->r.req) - ctx->r.req = mempool_alloc(&cc->req_pool, GFP_NOIO); + ctx->r.req = mempool_alloc(&cc->req_pool, in_interrupt() ? GFP_ATOMIC : GFP_NOIO);
skcipher_request_set_tfm(ctx->r.req, cc->cipher_tfm.tfms[key_index]);
@@ -1477,7 +1477,7 @@ static void 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); + ctx->r.req_aead = mempool_alloc(&cc->req_pool, in_interrupt() ? GFP_ATOMIC : GFP_NOIO);
aead_request_set_tfm(ctx->r.req_aead, cc->cipher_tfm.tfms_aead[0]);
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.
When Crypto API backlogs a crypto request, dm-crypt uses wait_for_completion to avoid sending further requests to an already overloaded crypto driver. However, if the code is executing in softirq context, we might get the following stacktrace:
[ 210.235213][ C0] BUG: scheduling while atomic: fio/2602/0x00000102 [ 210.236701][ C0] Modules linked in: [ 210.237566][ C0] CPU: 0 PID: 2602 Comm: fio Tainted: G W 5.10.0+ #50 [ 210.239292][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 [ 210.241233][ C0] Call Trace: [ 210.241946][ C0] <IRQ> [ 210.242561][ C0] dump_stack+0x7d/0xa3 [ 210.243466][ C0] __schedule_bug.cold+0xb3/0xc2 [ 210.244539][ C0] __schedule+0x156f/0x20d0 [ 210.245518][ C0] ? io_schedule_timeout+0x140/0x140 [ 210.246660][ C0] schedule+0xd0/0x270 [ 210.247541][ C0] schedule_timeout+0x1fb/0x280 [ 210.248586][ C0] ? usleep_range+0x150/0x150 [ 210.249624][ C0] ? unpoison_range+0x3a/0x60 [ 210.250632][ C0] ? ____kasan_kmalloc.constprop.0+0x82/0xa0 [ 210.251949][ C0] ? unpoison_range+0x3a/0x60 [ 210.252958][ C0] ? __prepare_to_swait+0xa7/0x190 [ 210.254067][ C0] do_wait_for_common+0x2ab/0x370 [ 210.255158][ C0] ? usleep_range+0x150/0x150 [ 210.256192][ C0] ? bit_wait_io_timeout+0x160/0x160 [ 210.257358][ C0] ? blk_update_request+0x757/0x1150 [ 210.258582][ C0] ? _raw_spin_lock_irq+0x82/0xd0 [ 210.259674][ C0] ? _raw_read_unlock_irqrestore+0x30/0x30 [ 210.260917][ C0] wait_for_completion+0x4c/0x90 [ 210.261971][ C0] crypt_convert+0x19a6/0x4c00 [ 210.263033][ C0] ? _raw_spin_lock_irqsave+0x87/0xe0 [ 210.264193][ C0] ? kasan_set_track+0x1c/0x30 [ 210.265191][ C0] ? crypt_iv_tcw_ctr+0x4a0/0x4a0 [ 210.266283][ C0] ? kmem_cache_free+0x104/0x470 [ 210.267363][ C0] ? crypt_endio+0x91/0x180 [ 210.268327][ C0] kcryptd_crypt_read_convert+0x30e/0x420 [ 210.269565][ C0] blk_update_request+0x757/0x1150 [ 210.270563][ C0] blk_mq_end_request+0x4b/0x480 [ 210.271680][ C0] blk_done_softirq+0x21d/0x340 [ 210.272775][ C0] ? _raw_spin_lock+0x81/0xd0 [ 210.273847][ C0] ? blk_mq_stop_hw_queue+0x30/0x30 [ 210.275031][ C0] ? _raw_read_lock_irq+0x40/0x40 [ 210.276182][ C0] __do_softirq+0x190/0x611 [ 210.277203][ C0] ? handle_edge_irq+0x221/0xb60 [ 210.278340][ C0] asm_call_irq_on_stack+0x12/0x20 [ 210.279514][ C0] </IRQ> [ 210.280164][ C0] do_softirq_own_stack+0x37/0x40 [ 210.281281][ C0] irq_exit_rcu+0x110/0x1b0 [ 210.282286][ C0] common_interrupt+0x74/0x120 [ 210.283376][ C0] asm_common_interrupt+0x1e/0x40 [ 210.284496][ C0] RIP: 0010:_aesni_enc1+0x65/0xb0
Fix this by making crypt_convert function reentrant from the point of a single bio and make dm-crypt defer further bio processing to a workqueue, if Crypto API backlogs a request in interrupt context.
Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workq ueues") Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Ignat Korchagin ignat@cloudflare.com --- drivers/md/dm-crypt.c | 102 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 97 insertions(+), 5 deletions(-)
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 777b5c71a2f7..6df907bd6c7c 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1529,13 +1529,19 @@ static void crypt_free_req(struct crypt_config *cc, void *req, struct bio *base_ * Encrypt / decrypt data from one bio to another one (can be the same one) */ static blk_status_t crypt_convert(struct crypt_config *cc, - struct convert_context *ctx, bool atomic) + struct convert_context *ctx, bool atomic, bool reset_pending) { unsigned int tag_offset = 0; unsigned int sector_step = cc->sector_size >> SECTOR_SHIFT; int r;
- atomic_set(&ctx->cc_pending, 1); + /* + * if reset_pending is set we are dealing with the bio for the first time, + * else we're continuing to work on the previous bio, so don't mess with + * the cc_pending counter + */ + if (reset_pending) + atomic_set(&ctx->cc_pending, 1);
while (ctx->iter_in.bi_size && ctx->iter_out.bi_size) {
@@ -1553,7 +1559,24 @@ static blk_status_t crypt_convert(struct crypt_config *cc, * but the driver request queue is full, let's wait. */ case -EBUSY: - wait_for_completion(&ctx->restart); + if (in_interrupt()) { + if (try_wait_for_completion(&ctx->restart)) { + /* + * we don't have to block to wait for completion, + * so proceed + */ + } else { + /* + * we can't wait for completion without blocking + * exit and continue processing in a workqueue + */ + ctx->r.req = NULL; + ctx->cc_sector += sector_step; + tag_offset++; + return BLK_STS_DEV_RESOURCE; + } + } else + wait_for_completion(&ctx->restart); reinit_completion(&ctx->restart); fallthrough; /* @@ -1945,6 +1968,37 @@ static bool kcryptd_crypt_write_inline(struct crypt_config *cc, } }
+static void kcryptd_crypt_write_continue(struct work_struct *work) +{ + struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); + struct crypt_config *cc = io->cc; + struct convert_context *ctx = &io->ctx; + int crypt_finished; + sector_t sector = io->sector; + blk_status_t r; + + wait_for_completion(&ctx->restart); + reinit_completion(&ctx->restart); + + r = crypt_convert(cc, &io->ctx, true, false); + if (r) + io->error = r; + crypt_finished = atomic_dec_and_test(&ctx->cc_pending); + if (!crypt_finished && kcryptd_crypt_write_inline(cc, ctx)) { + /* Wait for completion signaled by kcryptd_async_done() */ + wait_for_completion(&ctx->restart); + crypt_finished = 1; + } + + /* Encryption was already finished, submit io now */ + if (crypt_finished) { + kcryptd_crypt_write_io_submit(io, 0); + io->sector = sector; + } + + crypt_dec_pending(io); +} + static void kcryptd_crypt_write_convert(struct dm_crypt_io *io) { struct crypt_config *cc = io->cc; @@ -1973,7 +2027,17 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
crypt_inc_pending(io); r = crypt_convert(cc, ctx, - test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags)); + test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags), true); + /* + * Crypto API backlogged the request, because its queue was full + * and we're in softirq context, so continue from a workqueue + * (TODO: is it actually possible to be in softirq in the write path?) + */ + if (r == BLK_STS_DEV_RESOURCE) { + INIT_WORK(&io->work, kcryptd_crypt_write_continue); + queue_work(cc->crypt_queue, &io->work); + return; + } if (r) io->error = r; crypt_finished = atomic_dec_and_test(&ctx->cc_pending); @@ -1998,6 +2062,25 @@ static void kcryptd_crypt_read_done(struct dm_crypt_io *io) crypt_dec_pending(io); }
+static void kcryptd_crypt_read_continue(struct work_struct *work) +{ + struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); + struct crypt_config *cc = io->cc; + blk_status_t r; + + wait_for_completion(&io->ctx.restart); + reinit_completion(&io->ctx.restart); + + r = crypt_convert(cc, &io->ctx, true, false); + if (r) + io->error = r; + + if (atomic_dec_and_test(&io->ctx.cc_pending)) + kcryptd_crypt_read_done(io); + + crypt_dec_pending(io); +} + static void kcryptd_crypt_read_convert(struct dm_crypt_io *io) { struct crypt_config *cc = io->cc; @@ -2009,7 +2092,16 @@ static void kcryptd_crypt_read_convert(struct dm_crypt_io *io) io->sector);
r = crypt_convert(cc, &io->ctx, - test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags)); + test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags), true); + /* + * Crypto API backlogged the request, because its queue was full + * and we're in softirq context, so continue from a workqueue + */ + if (r == BLK_STS_DEV_RESOURCE) { + INIT_WORK(&io->work, kcryptd_crypt_read_continue); + queue_work(cc->crypt_queue, &io->work); + return; + } if (r) io->error = r;
Yes, good call!
Reposted with allocation failure handling.
Thanks, Ignat
On Wed, Dec 30, 2020 at 6:11 PM Mikulas Patocka mpatocka@redhat.com wrote:
linux-stable-mirror@lists.linaro.org
-
Ignat Korchagin -
Mikulas Patocka