Ignat Korchagin
8abec36d12
dm crypt: do not wait for backlogged crypto request completion in softirq ...
Commit 39d42fa96ba1 ("dm crypt: add flags to optionally bypass kcryptd
workqueues") 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 workqueues")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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8abec36d12