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BUG: KCSAN: data-race in oom_evaluate_task / try_to_free_mem_cgroup_pages

write to 0xffff88812453b0a4 of 4 bytes by task 7572 on cpu 0:
 memalloc_noreclaim_restore include/linux/sched/mm.h:283 [inline]
 try_to_free_mem_cgroup_pages+0x20d/0x4b0 mm/vmscan.c:3357
 try_charge+0x46b/0xbe0 mm/memcontrol.c:2455
 mem_cgroup_try_charge+0xd7/0x260 mm/memcontrol.c:6367
 mem_cgroup_try_charge_delay+0x36/0x70 mm/memcontrol.c:6382
 wp_page_copy+0x31a/0xf20 mm/memory.c:2516
 do_wp_page+0x185/0xcc0 mm/memory.c:2812
 handle_pte_fault mm/memory.c:4049 [inline]
 __handle_mm_fault+0x1c5e/0x2cf0 mm/memory.c:4163
 handle_mm_fault+0x21c/0x540 mm/memory.c:4200
 do_user_addr_fault arch/x86/mm/fault.c:1442 [inline]
 do_page_fault+0x4a4/0xa52 arch/x86/mm/fault.c:1517
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1203

read to 0xffff88812453b0a4 of 4 bytes by task 7581 on cpu 1:
 oom_unkillable_task mm/oom_kill.c:166 [inline]
 oom_evaluate_task+0x61/0x470 mm/oom_kill.c:315
 mem_cgroup_scan_tasks+0x90/0x140 mm/memcontrol.c:1190
 select_bad_process mm/oom_kill.c:369 [inline]
 out_of_memory mm/oom_kill.c:1099 [inline]
 out_of_memory+0x1af/0xa30 mm/oom_kill.c:1045
 mem_cgroup_out_of_memory+0x12b/0x150 mm/memcontrol.c:1575
 mem_cgroup_oom mm/memcontrol.c:1808 [inline]
 try_charge+0xb60/0xbe0 mm/memcontrol.c:2504
 mem_cgroup_try_charge+0xd7/0x260 mm/memcontrol.c:6367
 mem_cgroup_try_charge_delay+0x36/0x70 mm/memcontrol.c:6382
 shmem_getpage_gfp+0x3f5/0x14c0 mm/shmem.c:1872
 shmem_getpage mm/shmem.c:154 [inline]
 shmem_write_begin+0x98/0x130 mm/shmem.c:2488
 generic_perform_write+0x13a/0x320 mm/filemap.c:3287
 __generic_file_write_iter+0x240/0x370 mm/filemap.c:3416
 generic_file_write_iter+0x294/0x38e mm/filemap.c:3448
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:693
 do_iter_write fs/read_write.c:998 [inline]
 do_iter_write+0x137/0x3a0 fs/read_write.c:979
 vfs_iter_write+0x56/0x80 fs/read_write.c:1039
 iter_file_splice_write+0x530/0x830 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1575 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0xb8/0x140 fs/read_write.c:1567
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7581 Comm: syz-executor.5 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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