syzbot

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BUG: KCSAN: data-race in futex_wait_queue_me / get_task_mm

write to 0xffff8880b28df0a4 of 4 bytes by task 10306 on cpu 1:
 freezer_count include/linux/freezer.h:121 [inline]
 freezable_schedule include/linux/freezer.h:173 [inline]
 futex_wait_queue_me+0x19e/0x290 kernel/futex.c:2631
 futex_wait+0x17e/0x3a0 kernel/futex.c:2737
 do_futex+0xe2/0x15b0 kernel/futex.c:3808
 __do_sys_futex kernel/futex.c:3869 [inline]
 __se_sys_futex kernel/futex.c:3837 [inline]
 __x64_sys_futex+0x2dc/0x410 kernel/futex.c:3837
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b28df0a4 of 4 bytes by task 10310 on cpu 0:
 get_task_mm+0x4b/0x90 kernel/fork.c:1215
 do_task_stat+0xf5/0x1470 fs/proc/array.c:453
 proc_tgid_stat+0x39/0x50 fs/proc/array.c:632
 proc_single_show+0x8d/0x110 fs/proc/base.c:758
 seq_read+0x2ef/0x940 fs/seq_file.c:206
 do_loop_readv_writev fs/read_write.c:715 [inline]
 do_loop_readv_writev fs/read_write.c:702 [inline]
 do_iter_read+0x33f/0x3a0 fs/read_write.c:936
 vfs_readv+0x9c/0xf0 fs/read_write.c:1054
 do_preadv+0x129/0x1c0 fs/read_write.c:1146
 __do_sys_preadv fs/read_write.c:1196 [inline]
 __se_sys_preadv fs/read_write.c:1191 [inline]
 __x64_sys_preadv+0x5e/0x80 fs/read_write.c:1191
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10310 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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