syzbot

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BUG: KCSAN: data-race in __percpu_counter_compare / percpu_counter_add_batch

read-write to 0xffff888104916490 of 8 bytes by task 28100 on cpu 1:
 percpu_counter_add_batch+0xc9/0x140 lib/percpu_counter.c:96
 percpu_counter_add include/linux/percpu_counter.h:58 [inline]
 shmem_inode_acct_block mm/shmem.c:213 [inline]
 shmem_alloc_and_acct_folio mm/shmem.c:1592 [inline]
 shmem_get_folio_gfp+0x434/0x1120 mm/shmem.c:1937
 shmem_get_folio mm/shmem.c:2068 [inline]
 shmem_write_begin+0xa6/0x1e0 mm/shmem.c:2561
 generic_perform_write+0x1c3/0x3d0 mm/filemap.c:3926
 __generic_file_write_iter+0xe6/0x290 mm/filemap.c:4054
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4086
 call_write_iter include/linux/fs.h:1851 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x463/0x760 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:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888104916490 of 8 bytes by task 2435 on cpu 0:
 percpu_counter_read include/linux/percpu_counter.h:90 [inline]
 __percpu_counter_compare+0x2b/0x1d0 lib/percpu_counter.c:238
 percpu_counter_compare include/linux/percpu_counter.h:53 [inline]
 shmem_inode_acct_block mm/shmem.c:210 [inline]
 shmem_alloc_and_acct_folio mm/shmem.c:1592 [inline]
 shmem_get_folio_gfp+0x3fd/0x1120 mm/shmem.c:1937
 shmem_get_folio mm/shmem.c:2068 [inline]
 shmem_write_begin+0xa6/0x1e0 mm/shmem.c:2561
 generic_perform_write+0x1c3/0x3d0 mm/filemap.c:3926
 __generic_file_write_iter+0xe6/0x290 mm/filemap.c:4054
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4086
 call_write_iter include/linux/fs.h:1851 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x463/0x760 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:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000000000e0 -> 0x0000000000000100

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2435 Comm: udevd Not tainted 6.3.0-rc7-syzkaller-00189-g2caeeb9d4a1b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
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udevd[2435]: inotify_add_watch(7, /dev/loop4p5, 10) failed: No such file or directory
udevd[2435]: inotify_add_watch(7, /dev/loop0p207, 10) failed: No such file or directory