syzbot

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BUG: KCSAN: data-race in __percpu_counter_compare / percpu_counter_add_batch

write to 0xffff888126472b90 of 8 bytes by task 12654 on cpu 1:
 percpu_counter_add_batch+0xbd/0x130 lib/percpu_counter.c:91
 percpu_counter_add include/linux/percpu_counter.h:55 [inline]
 percpu_counter_sub include/linux/percpu_counter.h:189 [inline]
 shmem_inode_unacct_blocks mm/shmem.c:242 [inline]
 shmem_recalc_inode mm/shmem.c:309 [inline]
 shmem_undo_range+0xf15/0x1130 mm/shmem.c:990
 shmem_truncate_range mm/shmem.c:996 [inline]
 shmem_evict_inode+0x115/0x530 mm/shmem.c:1096
 evict+0x19f/0x470 fs/inode.c:576
 iput_final fs/inode.c:1652 [inline]
 iput+0x44a/0x550 fs/inode.c:1678
 do_unlinkat+0x2c9/0x4d0 fs/namei.c:3895
 __do_sys_unlink fs/namei.c:3936 [inline]
 __se_sys_unlink fs/namei.c:3934 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3934
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888126472b90 of 8 bytes by task 12648 on cpu 0:
 percpu_counter_read include/linux/percpu_counter.h:71 [inline]
 __percpu_counter_compare+0x28/0x1c0 lib/percpu_counter.c:206
 percpu_counter_compare include/linux/percpu_counter.h:50 [inline]
 shmem_inode_acct_block mm/shmem.c:223 [inline]
 shmem_alloc_and_acct_page+0x12c/0x650 mm/shmem.c:1521
 shmem_getpage_gfp+0x67c/0x1940 mm/shmem.c:1823
 shmem_getpage mm/shmem.c:153 [inline]
 shmem_write_begin+0x83/0x100 mm/shmem.c:2459
 generic_perform_write+0x196/0x390 mm/filemap.c:3318
 __generic_file_write_iter+0x154/0x330 mm/filemap.c:3447
 generic_file_write_iter+0x2f3/0x3e0 mm/filemap.c:3479
 call_write_iter include/linux/fs.h:1908 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x607/0x690 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12648 Comm: systemd-udevd Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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