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BUG: KCSAN: data-race in drain_all_stock / drain_stock

write to 0xffff888237d22e68 of 8 bytes by task 30333 on cpu 1:
 drain_stock+0x84/0x100 mm/memcontrol.c:2167
 refill_stock mm/memcontrol.c:2205 [inline]
 try_charge_memcg+0x7f2/0xa00 mm/memcontrol.c:2669
 try_charge mm/memcontrol.c:2722 [inline]
 charge_memcg mm/memcontrol.c:6688 [inline]
 __mem_cgroup_charge+0x3d/0x170 mm/memcontrol.c:6724
 mem_cgroup_charge include/linux/memcontrol.h:694 [inline]
 wp_page_copy+0x255/0x10a0 mm/memory.c:3022
 do_wp_page+0x5a8/0xba0
 handle_pte_fault mm/memory.c:4577 [inline]
 __handle_mm_fault mm/memory.c:4694 [inline]
 handle_mm_fault+0x96e/0x1580 mm/memory.c:4792
 do_user_addr_fault+0x609/0xbe0 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1485 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1541
 asm_exc_page_fault+0x1e/0x30

read to 0xffff888237d22e68 of 8 bytes by task 5 on cpu 0:
 drain_all_stock+0xa7/0x460 mm/memcontrol.c:2241
 mem_cgroup_css_offline+0x96/0x220 mm/memcontrol.c:5280
 offline_css kernel/cgroup/cgroup.c:5215 [inline]
 css_killed_work_fn+0x8d/0x210 kernel/cgroup/cgroup.c:5492
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

value changed: 0xffff888131255000 -> 0xffff8881310f5000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5 Comm: kworker/0:0 Tainted: G        W         5.15.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: cgroup_destroy css_killed_work_fn
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