On some specific hardware on early boot we occasionally get

[ 1193.920255][ T0] BUG: sleeping function called from invalid context at mm/mempool.c:381 [ 1193.936616][ T0] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/69 [ 1193.953233][ T0] no locks held by swapper/69/0. [ 1193.965871][ T0] irq event stamp: 575062 [ 1193.977724][ T0] hardirqs last enabled at (575061): [<ffffffffab73f662>] tick_nohz_idle_exit+0xe2/0x3e0 [ 1194.002762][ T0] hardirqs last disabled at (575062): [<ffffffffab74e8af>] flush_smp_call_function_from_idle+0x4f/0x80 [ 1194.029035][ T0] softirqs last enabled at (575050): [<ffffffffad600fd2>] asm_call_irq_on_stack+0x12/0x20 [ 1194.054227][ T0] softirqs last disabled at (575043): [<ffffffffad600fd2>] asm_call_irq_on_stack+0x12/0x20 [ 1194.079389][ T0] CPU: 69 PID: 0 Comm: swapper/69 Not tainted 5.10.6-cloudflare-kasan-2021.1.4-dev #1 [ 1194.104103][ T0] Hardware name: NULL R162-Z12-CD/MZ12-HD4-CD, BIOS R10 06/04/2020 [ 1194.119591][ T0] Call Trace: [ 1194.130233][ T0] dump_stack+0x9a/0xcc [ 1194.141617][ T0] ___might_sleep.cold+0x180/0x1b0 [ 1194.153825][ T0] mempool_alloc+0x16b/0x300 [ 1194.165313][ T0] ? remove_element+0x160/0x160 [ 1194.176961][ T0] ? blk_mq_end_request+0x4b/0x490 [ 1194.188778][ T0] crypt_convert+0x27f6/0x45f0 [dm_crypt] [ 1194.201024][ T0] ? rcu_read_lock_sched_held+0x3f/0x70 [ 1194.212906][ T0] ? module_assert_mutex_or_preempt+0x3e/0x70 [ 1194.225318][ T0] ? __module_address.part.0+0x1b/0x3a0 [ 1194.237212][ T0] ? is_kernel_percpu_address+0x5b/0x190 [ 1194.249238][ T0] ? crypt_iv_tcw_ctr+0x4a0/0x4a0 [dm_crypt] [ 1194.261593][ T0] ? is_module_address+0x25/0x40 [ 1194.272905][ T0] ? static_obj+0x8a/0xc0 [ 1194.283582][ T0] ? lockdep_init_map_waits+0x26a/0x700 [ 1194.295570][ T0] ? __raw_spin_lock_init+0x39/0x110 [ 1194.307330][ T0] kcryptd_crypt_read_convert+0x31c/0x560 [dm_crypt] [ 1194.320496][ T0] ? kcryptd_queue_crypt+0x1be/0x380 [dm_crypt] [ 1194.333203][ T0] blk_update_request+0x6d7/0x1500 [ 1194.344841][ T0] ? blk_mq_trigger_softirq+0x190/0x190 [ 1194.356831][ T0] blk_mq_end_request+0x4b/0x490 [ 1194.367994][ T0] ? blk_mq_trigger_softirq+0x190/0x190 [ 1194.379693][ T0] flush_smp_call_function_queue+0x24b/0x560 [ 1194.391847][ T0] flush_smp_call_function_from_idle+0x59/0x80 [ 1194.403969][ T0] do_idle+0x287/0x450 [ 1194.413891][ T0] ? arch_cpu_idle_exit+0x40/0x40 [ 1194.424716][ T0] ? lockdep_hardirqs_on_prepare+0x286/0x3f0 [ 1194.436399][ T0] ? _raw_spin_unlock_irqrestore+0x39/0x40 [ 1194.447759][ T0] cpu_startup_entry+0x19/0x20 [ 1194.458038][ T0] secondary_startup_64_no_verify+0xb0/0xbb

IO completion can be queued to a different CPU by the block subsystem as a "call single function/data". The CPU may run these routines from the idle task, but it does so with interrupts disabled.

It is not a good idea to do decryption with irqs disabled even in an idle task context, so just defer it to a tasklet as with requests from hard irqs.

Fixes: 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd workqueues") Cc: stable@vger.kernel.org # v5.9+ Signed-off-by: Ignat Korchagin ignat@cloudflare.com --- drivers/md/dm-crypt.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 53791138d78b..c56b01bfdb60 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -2091,8 +2091,11 @@ static void kcryptd_queue_crypt(struct dm_crypt_io *io)

if ((bio_data_dir(io->base_bio) == READ && test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags)) || (bio_data_dir(io->base_bio) == WRITE && test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags))) { - if (in_irq()) { - /* Crypto API's "skcipher_walk_first() refuses to work in hard IRQ context */ + /* in_irq(): Crypto API's "skcipher_walk_first() refuses to work in hard IRQ context. + * irqs_disabled(): the kernel may run some IO completion from the idle thread, but + it is being executed with irqs disabled. + */ + if (in_irq() || irqs_disabled()) { tasklet_init(&io->tasklet, kcryptd_crypt_tasklet, (unsigned long)&io->work); tasklet_schedule(&io->tasklet); return;