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BUG: KCSAN: data-race in drain_all_stock / try_charge

write to 0xffff88812c12a108 of 4 bytes by task 3057 on cpu 1:
 consume_stock mm/memcontrol.c:2066 [inline]
 try_charge+0x364/0xbf0 mm/memcontrol.c:2400
 mem_cgroup_try_charge+0xd2/0x260 mm/memcontrol.c:6404
 mem_cgroup_try_charge_delay+0x3a/0x80 mm/memcontrol.c:6419
 shmem_getpage_gfp+0x3bf/0x1390 mm/shmem.c:1872
 shmem_fault+0x114/0x470 mm/shmem.c:2067
 __do_fault+0xae/0x1f0 mm/memory.c:3188
 do_read_fault mm/memory.c:3585 [inline]
 do_fault mm/memory.c:3714 [inline]
 handle_pte_fault mm/memory.c:3945 [inline]
 __handle_mm_fault+0x270d/0x2e00 mm/memory.c:4075
 handle_mm_fault+0x21b/0x530 mm/memory.c:4112
 faultin_page mm/gup.c:640 [inline]
 __get_user_pages+0x485/0x1130 mm/gup.c:851
 populate_vma_page_range+0xe6/0x100 mm/gup.c:1235
 __mm_populate+0x168/0x2a0 mm/gup.c:1283
 mm_populate include/linux/mm.h:2347 [inline]
 vm_mmap_pgoff+0x181/0x190 mm/util.c:511
 ksys_mmap_pgoff+0x99/0x420 mm/mmap.c:1607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812c12a108 of 4 bytes by task 3091 on cpu 0:
 drain_all_stock mm/memcontrol.c:2159 [inline]
 drain_all_stock+0xe5/0x250 mm/memcontrol.c:2138
 try_charge+0x79b/0xbf0 mm/memcontrol.c:2462
 __memcg_kmem_charge_memcg+0x4a/0xe0 mm/memcontrol.c:2837
 __memcg_kmem_charge+0xcf/0x1b0 mm/memcontrol.c:2877
 memcg_kmem_charge include/linux/memcontrol.h:1395 [inline]
 memcg_charge_kernel_stack kernel/fork.c:421 [inline]
 dup_task_struct kernel/fork.c:876 [inline]
 copy_process+0x11d2/0x3c40 kernel/fork.c:1911
 _do_fork+0xfe/0x7a0 kernel/fork.c:2421
 __do_sys_clone kernel/fork.c:2576 [inline]
 __se_sys_clone kernel/fork.c:2557 [inline]
 __x64_sys_clone+0x130/0x170 kernel/fork.c:2557
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3091 Comm: syz-executor.4 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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