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BUG: KCSAN: data-race in filemap_map_pages / shmem_write_end

write to 0xffff88801ec40410 of 8 bytes by task 23411 on cpu 0:
 i_size_write include/linux/fs.h:870 [inline]
 shmem_write_end+0x62/0x650 mm/shmem.c:2539
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3423
 __generic_file_write_iter+0x15c/0x340 mm/filemap.c:3541
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3573
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x41a/0x770 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 fs/splice.c:888
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x5e0/0xcf0 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88801ec40410 of 8 bytes by task 23423 on cpu 1:
 i_size_read include/linux/fs.h:848 [inline]
 filemap_map_pages+0x481/0x9b0 mm/filemap.c:2960
 do_fault_around mm/memory.c:3980 [inline]
 do_read_fault+0x22f/0x720 mm/memory.c:4014
 do_fault mm/memory.c:4147 [inline]
 handle_pte_fault mm/memory.c:4387 [inline]
 __handle_mm_fault mm/memory.c:4522 [inline]
 handle_mm_fault+0x100c/0x1810 mm/memory.c:4620
 faultin_page mm/gup.c:851 [inline]
 __get_user_pages+0xa42/0x1000 mm/gup.c:1070
 __get_user_pages_locked mm/gup.c:1256 [inline]
 __get_user_pages_remote+0x226/0x6e0 mm/gup.c:1723
 get_user_pages_remote+0x6f/0xa0 mm/gup.c:1796
 uprobe_write_opcode+0xc9/0xd60 kernel/events/uprobes.c:480
 set_swbp+0x26/0x30
 install_breakpoint+0x224/0x350 kernel/events/uprobes.c:915
 uprobe_mmap+0x7cd/0xc70 kernel/events/uprobes.c:1394
 mmap_region+0x881/0x1480 mm/mmap.c:1884
 do_mmap+0x77d/0xc90 mm/mmap.c:1583
 vm_mmap_pgoff+0xf7/0x1d0 mm/util.c:519
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1634
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23423 Comm: syz-executor.3 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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