syzbot

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BUG: KCSAN: data-race in do_mpage_readpage / set_blocksize

write to 0xffff8881004c10ae of 1 bytes by task 5066 on cpu 0:
 set_blocksize+0x218/0x270 block/bdev.c:173
 sb_set_blocksize block/bdev.c:186 [inline]
 sb_min_blocksize+0xb7/0x140 block/bdev.c:201
 ext4_load_super fs/ext4/super.c:5027 [inline]
 __ext4_fill_super fs/ext4/super.c:5248 [inline]
 ext4_fill_super+0x399/0x3650 fs/ext4/super.c:5722
 get_tree_bdev_flags+0x2b4/0x330 fs/super.c:1636
 get_tree_bdev+0x1f/0x30 fs/super.c:1659
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5754
 vfs_get_tree+0x56/0x1e0 fs/super.c:1759
 do_new_mount+0x246/0x6b0 fs/namespace.c:3878
 path_mount+0x49b/0xb30 fs/namespace.c:4205
 do_mount fs/namespace.c:4218 [inline]
 __do_sys_mount fs/namespace.c:4429 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4406
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4406
 x64_sys_call+0xd11/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881004c10ae of 1 bytes by task 3294 on cpu 1:
 do_mpage_readpage+0x53/0xd60 fs/mpage.c:155
 mpage_readahead+0x1af/0x2d0 fs/mpage.c:371
 blkdev_readahead+0x1c/0x30 block/fops.c:472
 read_pages+0xa1/0x470 mm/readahead.c:160
 page_cache_ra_unbounded+0x30d/0x350 mm/readahead.c:297
 do_page_cache_ra mm/readahead.c:327 [inline]
 force_page_cache_ra mm/readahead.c:356 [inline]
 page_cache_sync_ra+0x252/0x680 mm/readahead.c:575
 filemap_get_pages+0x2ba/0x11b0 mm/filemap.c:2602
 filemap_read+0x231/0x8d0 mm/filemap.c:2713
 blkdev_read_iter+0x227/0x2d0 block/fops.c:796
 new_sync_read fs/read_write.c:489 [inline]
 vfs_read+0x5e6/0x710 fs/read_write.c:570
 ksys_read+0xeb/0x1b0 fs/read_write.c:713
 __do_sys_read fs/read_write.c:722 [inline]
 __se_sys_read fs/read_write.c:720 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:720
 x64_sys_call+0x2a3b/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0c -> 0x0a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3294 Comm: udevd Not tainted 6.14.0-syzkaller-05877-g1a9239bb4253 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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