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BUG: KCSAN: data-race in __lru_cache_add / lru_add_drain_all

read to 0xffff88812c1299e0 of 1 bytes by task 9011 on cpu 0:
 lru_add_drain_all+0x17e/0x3d0 mm/swap.c:746
 invalidate_bdev+0x6e/0x90 fs/block_dev.c:97
 __loop_clr_fd+0x250/0x740 drivers/block/loop.c:1140
 loop_clr_fd drivers/block/loop.c:1237 [inline]
 lo_ioctl+0x24c/0xc80 drivers/block/loop.c:1606
 __blkdev_driver_ioctl block/ioctl.c:277 [inline]
 blkdev_ioctl+0xbe5/0x1260 block/ioctl.c:582
 block_ioctl+0x95/0xc0 fs/block_dev.c:1983
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x84f/0xcf0 fs/ioctl.c:732
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:754
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812c1299e0 of 1 bytes by task 9000 on cpu 1:
 pagevec_add include/linux/pagevec.h:81 [inline]
 __lru_cache_add+0xbf/0x1d0 mm/swap.c:410
 lru_cache_add_anon+0x9e/0x130 mm/swap.c:423
 shmem_getpage_gfp+0x470/0x1390 mm/shmem.c:1885
 shmem_fault+0x114/0x470 mm/shmem.c:2067
 __do_fault+0xae/0x1f0 mm/memory.c:3188
 do_read_fault mm/memory.c:3585 [inline]
 do_fault mm/memory.c:3714 [inline]
 handle_pte_fault mm/memory.c:3945 [inline]
 __handle_mm_fault+0x270d/0x2e00 mm/memory.c:4075
 handle_mm_fault+0x21b/0x530 mm/memory.c:4112
 faultin_page mm/gup.c:640 [inline]
 __get_user_pages+0x485/0x1130 mm/gup.c:851
 populate_vma_page_range+0xe6/0x100 mm/gup.c:1235
 __mm_populate+0x168/0x2a0 mm/gup.c:1283
 mm_populate include/linux/mm.h:2347 [inline]
 vm_mmap_pgoff+0x181/0x190 mm/util.c:511
 ksys_mmap_pgoff+0x99/0x420 mm/mmap.c:1607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9000 Comm: syz-executor.2 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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