syzbot

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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff888100481838 of 8 bytes by task 10789 on cpu 0:
 __filemap_add_folio+0x5b9/0x7d0 mm/filemap.c:928
 filemap_add_folio+0x98/0x1b0 mm/filemap.c:969
 do_read_cache_folio+0xd4/0x5b0 mm/filemap.c:3924
 read_cache_folio+0x3c/0x50 mm/filemap.c:3989
 read_mapping_folio include/linux/pagemap.h:991 [inline]
 read_part_sector+0x6f/0x150 block/partitions/core.c:722
 read_lba+0x100/0x1e0 block/partitions/efi.c:248
 alloc_read_gpt_entries+0x7b/0xd0 block/partitions/efi.c:288
 is_gpt_valid+0x33f/0x3e0 block/partitions/efi.c:430
 find_valid_gpt block/partitions/efi.c:615 [inline]
 efi_partition+0x132/0x1400 block/partitions/efi.c:720
 check_partition block/partitions/core.c:141 [inline]
 blk_add_partitions block/partitions/core.c:589 [inline]
 bdev_disk_changed+0x4b6/0xcb0 block/partitions/core.c:693
 loop_reread_partitions drivers/block/loop.c:439 [inline]
 loop_set_status+0x541/0x5f0 drivers/block/loop.c:1265
 loop_set_status64 drivers/block/loop.c:1361 [inline]
 lo_ioctl+0x68f/0x1350 drivers/block/loop.c:1547
 blkdev_ioctl+0x34f/0x440 block/ioctl.c:705
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:584
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
 x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100481838 of 8 bytes by task 23 on cpu 1:
 nr_blockdev_pages+0x7e/0xd0 block/bdev.c:523
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 update_defense_level+0x47/0x5c0 net/netfilter/ipvs/ip_vs_ctl.c:102
 defense_work_handler+0x1f/0x80 net/netfilter/ipvs/ip_vs_ctl.c:235
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 kernel/kthread.c:463
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000059 -> 0x000000000000005a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 23 Comm: kworker/1:0 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_long defense_work_handler
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