syzbot

loop5: detected capacity change from 0 to 512
EXT4-fs (loop5): mounting ext2 file system using the ext4 subsystem
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BUG: KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead

write to 0xffff8881046b16a0 of 4 bytes by task 20553 on cpu 0:
 do_sync_mmap_readahead+0x2ea/0x370 mm/filemap.c:3025
 filemap_fault+0x192/0x750 mm/filemap.c:3120
 __do_fault mm/memory.c:4173 [inline]
 do_shared_fault mm/memory.c:4573 [inline]
 do_fault+0x5df/0xb20 mm/memory.c:4651
 handle_pte_fault mm/memory.c:4911 [inline]
 __handle_mm_fault mm/memory.c:5053 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5151
 do_user_addr_fault+0x4a1/0x980 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1488 [inline]
 exc_page_fault+0x60/0x160 arch/x86/mm/fault.c:1544
 asm_exc_page_fault+0x22/0x30

write to 0xffff8881046b16a0 of 4 bytes by task 20555 on cpu 1:
 do_sync_mmap_readahead+0x2ea/0x370 mm/filemap.c:3025
 filemap_fault+0x192/0x750 mm/filemap.c:3120
 __do_fault mm/memory.c:4173 [inline]
 do_read_fault mm/memory.c:4518 [inline]
 do_fault+0x500/0xb20 mm/memory.c:4647
 handle_pte_fault mm/memory.c:4911 [inline]
 __handle_mm_fault mm/memory.c:5053 [inline]
 handle_mm_fault+0x889/0xa90 mm/memory.c:5151
 do_user_addr_fault+0x4a1/0x980 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1488 [inline]
 exc_page_fault+0x60/0x160 arch/x86/mm/fault.c:1544
 asm_exc_page_fault+0x22/0x30
 strncpy_from_user+0xd4/0x230 lib/strncpy_from_user.c:139
 getname_flags+0xb0/0x350 fs/namei.c:150
 getname+0x15/0x20 fs/namei.c:218
 do_sys_openat2+0x6d/0x2a0 fs/open.c:1305
 do_sys_open fs/open.c:1327 [inline]
 __do_sys_openat fs/open.c:1343 [inline]
 __se_sys_openat fs/open.c:1338 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1338
 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+0x63/0xcd

value changed: 0x00000000 -> 0x00000020

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20555 Comm: syz-executor.5 Not tainted 6.0.0-rc2-syzkaller-00283-g10d4879f9ef0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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