KCSAN: data-race in padata_find_next / padata_reorder

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 766d004d mm, kcsan: Instrument SLAB free with ASSERT_EXCLU..
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=11ba9129e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=cd9253e6e662bbb3
dashboard link: https://syzkaller.appspot.com/bug?extid=f7655ab267abd1c642ee
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org steffen....@secunet.com el...@google.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f7655a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in padata_find_next / padata_reorder

write to 0xffff8880bb6acc24 of 4 bytes by task 340 on cpu 0:
padata_find_next+0x1d5/0x260 kernel/padata.c:206
padata_reorder+0x18b/0x270 kernel/padata.c:235
padata_do_serial+0x17a/0x1b0 kernel/padata.c:347
pcrypt_aead_enc+0x51/0x80 crypto/pcrypt.c:87
padata_parallel_worker+0x1ae/0x220 kernel/padata.c:83
process_one_work+0x413/0x8f0 kernel/workqueue.c:2264
worker_thread+0xa0/0x800 kernel/workqueue.c:2410
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff8880bb6acc24 of 4 bytes by task 8266 on cpu 1:
padata_reorder+0x1c1/0x270 kernel/padata.c:267
padata_do_serial+0x17a/0x1b0 kernel/padata.c:347
pcrypt_aead_enc+0x51/0x80 crypto/pcrypt.c:87
padata_parallel_worker+0x1ae/0x220 kernel/padata.c:83
process_one_work+0x413/0x8f0 kernel/workqueue.c:2264
worker_thread+0xa0/0x800 kernel/workqueue.c:2410
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8266 Comm: kworker/u4:5 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: pencrypt_parallel padata_parallel_worker
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.