syzbot

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BUG: KCSAN: data-race in __percpu_counter_compare / percpu_counter_add_batch

read-write to 0xffff888100135b50 of 8 bytes by task 8549 on cpu 0:
 percpu_counter_add_batch+0xc9/0x140 lib/percpu_counter.c:96
 shmem_inode_acct_block+0x1ee/0x220
 shmem_alloc_and_acct_folio mm/shmem.c:1676 [inline]
 shmem_get_folio_gfp+0x4ad/0xc30 mm/shmem.c:2020
 shmem_get_folio mm/shmem.c:2143 [inline]
 shmem_write_begin+0xa6/0x210 mm/shmem.c:2688
 generic_perform_write+0x1c9/0x410 mm/filemap.c:3969
 shmem_file_write_iter+0xc8/0xe0 mm/shmem.c:2865
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x48a/0x790 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888100135b50 of 8 bytes by task 8552 on cpu 1:
 percpu_counter_read include/linux/percpu_counter.h:101 [inline]
 __percpu_counter_compare+0x2b/0x1d0 lib/percpu_counter.c:262
 percpu_counter_compare include/linux/percpu_counter.h:64 [inline]
 shmem_inode_acct_block+0xf6/0x220 mm/shmem.c:221
 shmem_alloc_and_acct_folio mm/shmem.c:1676 [inline]
 shmem_get_folio_gfp+0x4ad/0xc30 mm/shmem.c:2020
 shmem_get_folio mm/shmem.c:2143 [inline]
 shmem_write_begin+0xa6/0x210 mm/shmem.c:2688
 generic_perform_write+0x1c9/0x410 mm/filemap.c:3969
 shmem_file_write_iter+0xc8/0xe0 mm/shmem.c:2865
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x48a/0x790 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000423 -> 0x0000000000000443

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8552 Comm: syz-executor.2 Not tainted 6.6.0-syzkaller-10396-g4652b8e4f3ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
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