syzbot

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BUG: KCSAN: data-race in task_dump_owner / try_to_free_mem_cgroup_pages

write to 0xffff8881029a00a4 of 4 bytes by task 27170 on cpu 0:
 memalloc_noreclaim_save include/linux/sched/mm.h:277 [inline]
 try_to_free_mem_cgroup_pages+0x1dd/0x4b0 mm/vmscan.c:3353
 reclaim_high.constprop.0+0xee/0x140 mm/memcontrol.c:2232
 mem_cgroup_handle_over_high+0x8f/0x180 mm/memcontrol.c:2313
 tracehook_notify_resume include/linux/tracehook.h:197 [inline]
 exit_to_usermode_loop+0x20a/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode+0x190/0x1c0 arch/x86/entry/common.c:195
 swapgs_restore_regs_and_return_to_usermode+0x0/0x40

read to 0xffff8881029a00a4 of 4 bytes by task 27299 on cpu 1:
 task_dump_owner+0x42/0x250 fs/proc/base.c:1789
 pid_update_inode+0x35/0x70 fs/proc/base.c:1909
 pid_revalidate+0x89/0x110 fs/proc/base.c:1932
 d_revalidate fs/namei.c:766 [inline]
 d_revalidate fs/namei.c:763 [inline]
 lookup_fast+0x63a/0x6e0 fs/namei.c:1712
 walk_component+0x73/0x9a0 fs/namei.c:1911
 link_path_walk.part.0+0x5e5/0xa80 fs/namei.c:2241
 link_path_walk fs/namei.c:2172 [inline]
 path_openat+0x14c/0x2f70 fs/namei.c:3606
 do_filp_open+0x11e/0x1b0 fs/namei.c:3637
 do_sys_openat2+0x4f5/0x620 fs/open.c:1149
 do_sys_open+0xa2/0x110 fs/open.c:1165
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_open fs/open.c:1171 [inline]
 __se_sys_open fs/open.c:1169 [inline]
 __x64_sys_open+0x50/0x60 fs/open.c:1169
 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: 27299 Comm: syz-executor.2 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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