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BUG: KCSAN: data-race in shmem_getattr / shmem_recalc_inode

read-write to 0xffff88812251e008 of 8 bytes by task 5575 on cpu 0:
 shmem_recalc_inode+0x36/0x1b0 mm/shmem.c:437
 shmem_alloc_and_add_folio mm/shmem.c:1868 [inline]
 shmem_get_folio_gfp+0x7ce/0xd90 mm/shmem.c:2332
 shmem_get_folio mm/shmem.c:2438 [inline]
 shmem_write_begin+0xa2/0x180 mm/shmem.c:3043
 generic_perform_write+0x1a8/0x4a0 mm/filemap.c:4054
 shmem_file_write_iter+0xc2/0xe0 mm/shmem.c:3218
 iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x39b/0x970 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64 fs/read_write.c:1441 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
 x64_sys_call+0xed5/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88812251e008 of 8 bytes by task 5577 on cpu 1:
 shmem_getattr+0x42/0x210 mm/shmem.c:1157
 vfs_getattr_nosec fs/stat.c:166 [inline]
 vfs_getattr+0x19b/0x1e0 fs/stat.c:207
 vfs_statx_path fs/stat.c:251 [inline]
 vfs_statx+0x134/0x2f0 fs/stat.c:315
 vfs_fstatat fs/stat.c:341 [inline]
 vfs_lstat include/linux/fs.h:3362 [inline]
 __do_sys_newlstat fs/stat.c:491 [inline]
 __se_sys_newlstat+0x6a/0x280 fs/stat.c:485
 __x64_sys_newlstat+0x31/0x40 fs/stat.c:485
 x64_sys_call+0x1d1e/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:7
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000a1d -> 0x0000000000000a20

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5577 Comm: syz.0.639 Not tainted 6.12.0-rc5-syzkaller-00299-g11066801dd4b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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