[moderation] [exfat?] KCSAN: data-race in filemap_fault / generic_write_end (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6bdfe2d88b9f Merge tag 'apparmor-pr-2023-11-03' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14ddc37f680000
kernel config: https://syzkaller.appspot.com/x/.config?x=bbdaf57f4e1c9873
dashboard link: https://syzkaller.appspot.com/bug?extid=a4e28512dee4c8b02065
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [hiro...@mail.parknet.co.jp linki...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org sj155...@samsung.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/05908e47274c/disk-6bdfe2d8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b9e2a2b752f3/vmlinux-6bdfe2d8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9eded1242486/bzImage-6bdfe2d8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4e285...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 128
==================================================================
BUG: KCSAN: data-race in filemap_fault / generic_write_end

write to 0xffff88813a89ca00 of 8 bytes by task 19739 on cpu 1:
i_size_write include/linux/fs.h:932 [inline]
generic_write_end+0x94/0x230 fs/buffer.c:2291
fat_write_end+0x4e/0x160 fs/fat/inode.c:244
cont_expand_zero fs/buffer.c:2514 [inline]
cont_write_begin+0x2c0/0x690 fs/buffer.c:2572
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_cont_expand_simple+0xa7/0x140 fs/buffer.c:2473
fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
fat_fallocate+0x182/0x1d0 fs/fat/file.c:301
vfs_fallocate+0x378/0x3e0 fs/open.c:324
ksys_fallocate fs/open.c:347 [inline]
__do_sys_fallocate fs/open.c:355 [inline]
__se_sys_fallocate fs/open.c:353 [inline]
__x64_sys_fallocate+0x79/0xc0 fs/open.c:353
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88813a89ca00 of 8 bytes by task 19735 on cpu 0:
i_size_read include/linux/fs.h:910 [inline]
filemap_fault+0x91/0xc30 mm/filemap.c:3209
__do_fault mm/memory.c:4265 [inline]
do_read_fault mm/memory.c:4628 [inline]
do_fault mm/memory.c:4762 [inline]
do_pte_missing mm/memory.c:3730 [inline]
handle_pte_fault mm/memory.c:5038 [inline]
__handle_mm_fault mm/memory.c:5179 [inline]
handle_mm_fault+0x13bd/0x2dd0 mm/memory.c:5344
faultin_page mm/gup.c:956 [inline]
__get_user_pages+0x402/0xe40 mm/gup.c:1239
populate_vma_page_range mm/gup.c:1677 [inline]
__mm_populate+0x216/0x330 mm/gup.c:1786
mm_populate include/linux/mm.h:3379 [inline]
vm_mmap_pgoff+0x1a7/0x240 mm/util.c:551
ksys_mmap_pgoff+0x2b8/0x330 mm/mmap.c:1425
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000012000 -> 0x0000000000014000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19735 Comm: syz-executor.2 Not tainted 6.6.0-syzkaller-12715-g6bdfe2d88b9f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.