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BUG: KCSAN: data-race in __percpu_counter_compare / percpu_counter_add_batch

write to 0xffff88813a7a8c10 of 8 bytes by task 7770 on cpu 1:
 percpu_counter_add_batch+0x9c/0xd0 lib/percpu_counter.c:91
 percpu_counter_add include/linux/percpu_counter.h:56 [inline]
 shmem_inode_acct_block mm/shmem.c:224 [inline]
 shmem_alloc_and_acct_page mm/shmem.c:1600 [inline]
 shmem_getpage_gfp+0x8c9/0x13c0 mm/shmem.c:1901
 shmem_getpage mm/shmem.c:151 [inline]
 shmem_write_begin+0x7e/0x100 mm/shmem.c:2469
 generic_perform_write+0x1a6/0x3d0 mm/filemap.c:3770
 __generic_file_write_iter+0x174/0x310 mm/filemap.c:3897
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3929
 call_write_iter include/linux/fs.h:2163 [inline]
 aio_write+0x287/0x360 fs/aio.c:1578
 io_submit_one+0x82f/0x1350 fs/aio.c:1880
 __do_sys_io_submit fs/aio.c:1939 [inline]
 __se_sys_io_submit+0xf5/0x260 fs/aio.c:1909
 __x64_sys_io_submit+0x3f/0x50 fs/aio.c:1909
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813a7a8c10 of 8 bytes by task 7788 on cpu 0:
 percpu_counter_read include/linux/percpu_counter.h:72 [inline]
 __percpu_counter_compare+0x28/0x1a0 lib/percpu_counter.c:225
 percpu_counter_compare include/linux/percpu_counter.h:51 [inline]
 shmem_inode_acct_block mm/shmem.c:221 [inline]
 shmem_alloc_and_acct_page mm/shmem.c:1600 [inline]
 shmem_getpage_gfp+0x858/0x13c0 mm/shmem.c:1901
 shmem_fault+0xcf/0x470 mm/shmem.c:2113
 __do_fault mm/memory.c:3857 [inline]
 do_read_fault mm/memory.c:4172 [inline]
 do_fault mm/memory.c:4300 [inline]
 handle_pte_fault mm/memory.c:4558 [inline]
 __handle_mm_fault mm/memory.c:4693 [inline]
 handle_mm_fault+0xb8f/0x1530 mm/memory.c:4791
 faultin_page mm/gup.c:937 [inline]
 __get_user_pages+0x381/0xc50 mm/gup.c:1158
 populate_vma_page_range mm/gup.c:1490 [inline]
 __mm_populate+0x24d/0x380 mm/gup.c:1599
 mm_populate include/linux/mm.h:2624 [inline]
 vm_mmap_pgoff+0x142/0x1d0 mm/util.c:524
 ksys_mmap_pgoff+0x284/0x350 mm/mmap.c:1624
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000001160 -> 0x0000000000001180

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7788 Comm: syz-executor.3 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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