KCSAN: data-race in cgroup_rstat_flush_locked / cgroup_rstat_updated

[Hao Sun]

Hi

KCSAN reported the following data race during the kernel booting when
using Healer to fuzz the latest Linux kernel.

HEAD commit: ff1ffd71d5f0 Merge tag 'hyperv-fixes-signed-20210915'
git tree: upstream
console output: https://paste.ubuntu.com/p/s4kFHrHCNh/
kernel config: https://paste.ubuntu.com/p/FjTsrWnBVM/

If you fix this issue, please add the following tag to the commit:
Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>

==================================================================
BUG: KCSAN: data-race in cgroup_rstat_flush_locked / cgroup_rstat_updated

write to 0xffffe8ffffc194d0 of 8 bytes by task 8 on cpu 1:
 cgroup_rstat_cpu_pop_updated kernel/cgroup/rstat.c:139 [inline]
 cgroup_rstat_flush_locked+0x282/0x760 kernel/cgroup/rstat.c:161
 cgroup_rstat_flush_irqsafe+0x24/0x40 kernel/cgroup/rstat.c:218
 mem_cgroup_flush_stats mm/memcontrol.c:5354 [inline]
 flush_memcg_stats_work+0x34/0x60 mm/memcontrol.c:5366
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x638/0xac0 kernel/workqueue.c:2444
 kthread+0x243/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

read to 0xffffe8ffffc194d0 of 8 bytes by task 1245 on cpu 0:
 cgroup_rstat_updated+0x53/0x1b0 kernel/cgroup/rstat.c:38
 __count_memcg_events+0x43/0x50 mm/memcontrol.c:788
 __activate_page+0x50b/0x5f0 mm/swap.c:309
 pagevec_lru_move_fn+0x1c4/0x2d0 mm/swap.c:197
 activate_page mm/swap.c:338 [inline]
 mark_page_accessed+0x47d/0x550 mm/swap.c:422
 zap_pte_range+0x5cc/0xdb0 mm/memory.c:1359
 zap_pmd_range mm/memory.c:1481 [inline]
 zap_pud_range mm/memory.c:1510 [inline]
 zap_p4d_range mm/memory.c:1531 [inline]
 unmap_page_range+0x2dc/0x3d0 mm/memory.c:1552
 unmap_single_vma+0x157/0x210 mm/memory.c:1597
 unmap_vmas+0xd0/0x180 mm/memory.c:1629
 exit_mmap+0x235/0x470 mm/mmap.c:3171
 __mmput+0x27/0x1d0 kernel/fork.c:1115
 mmput+0x3d/0x50 kernel/fork.c:1136
 exit_mm+0x2dc/0x3d0 kernel/exit.c:501
 do_exit+0x3e0/0x14f0 kernel/exit.c:812
 do_group_exit+0xa4/0x1a0 kernel/exit.c:922
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:933
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:931
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:931
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888101bc2010 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1245 Comm: syz-executor Not tainted 5.15.0-rc1+ #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014