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BUG: KCSAN: data-race in loop_configure / shmem_file_read_iter

write to 0xffff888137d02570 of 4 bytes by task 22934 on cpu 1:
 mapping_set_gfp_mask include/linux/pagemap.h:290 [inline]
 loop_configure+0x83c/0xc90 drivers/block/loop.c:1036
 lo_ioctl+0x617/0x11b0
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:588
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 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+0x44/0xae

read to 0xffff888137d02570 of 4 bytes by task 22953 on cpu 0:
 mapping_gfp_mask include/linux/pagemap.h:274 [inline]
 shmem_getpage mm/shmem.c:150 [inline]
 shmem_file_read_iter+0x136/0x6a0 mm/shmem.c:2526
 call_read_iter include/linux/fs.h:2044 [inline]
 generic_file_splice_read+0x1de/0x2c0 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2ac/0x660 fs/splice.c:870
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1297
 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+0x44/0xae

value changed: 0x00100cca -> 0x00100c0a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22953 Comm: syz-executor.4 Not tainted 5.18.0-rc7-syzkaller-00006-g210e04ff7681-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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