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BUG: KCSAN: data-race in next_uptodate_page / shmem_write_end

write to 0xffff8881093043d8 of 8 bytes by task 21054 on cpu 1:
 i_size_write include/linux/fs.h:886 [inline]
 shmem_write_end+0x59/0x380 mm/shmem.c:2535
 generic_perform_write+0x264/0x3f0 mm/filemap.c:3749
 __generic_file_write_iter+0xe3/0x280 mm/filemap.c:3866
 generic_file_write_iter+0x79/0x1c0 mm/filemap.c:3898
 do_iter_write+0x494/0x750 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x44a/0x7c0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:931
 splice_direct_to_actor+0x305/0x620 fs/splice.c:886
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0xb9/0x150 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881093043d8 of 8 bytes by task 21052 on cpu 0:
 i_size_read include/linux/fs.h:864 [inline]
 next_uptodate_page+0x2d4/0x520 mm/filemap.c:3293
 next_map_page mm/filemap.c:3318 [inline]
 filemap_map_pages+0x9d1/0xae0 mm/filemap.c:3390
 do_fault_around mm/memory.c:4487 [inline]
 do_read_fault mm/memory.c:4513 [inline]
 do_fault+0x433/0xb20 mm/memory.c:4647
 handle_pte_fault mm/memory.c:4911 [inline]
 __handle_mm_fault mm/memory.c:5053 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5151
 do_user_addr_fault+0x4a1/0x980 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1488 [inline]
 exc_page_fault+0x60/0x160 arch/x86/mm/fault.c:1544
 asm_exc_page_fault+0x22/0x30

value changed: 0x0000000000004ee4 -> 0x0000000000004eed

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21052 Comm: syz-executor.0 Not tainted 6.0.0-rc3-syzkaller-00215-g0b3acd1cc022-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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