KCSAN: data-race in filemap_map_pages / generic_write_end (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 22fbc037 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=145889c7900000
kernel config: https://syzkaller.appspot.com/x/.config?x=9c2006d5acc5d93b
dashboard link: https://syzkaller.appspot.com/bug?extid=f019ed0076eb4b161808
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f019ed...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in filemap_map_pages / generic_write_end

write to 0xffff88811edabb88 of 8 bytes by task 13908 on cpu 0:
i_size_write include/linux/fs.h:876 [inline]
generic_write_end+0x99/0x250 fs/buffer.c:2186
ext4_da_write_end+0x57e/0x760 fs/ext4/inode.c:3091
generic_perform_write+0x23b/0x390 mm/filemap.c:3516
ext4_buffered_write_iter+0x2cc/0x3b0 fs/ext4/file.c:269
ext4_file_write_iter+0x768/0x1060 include/linux/fs.h:784
call_write_iter include/linux/fs.h:1882 [inline]
new_sync_write fs/read_write.c:503 [inline]
vfs_write+0x665/0x6f0 fs/read_write.c:586
ksys_write+0xce/0x180 fs/read_write.c:639
__do_sys_write fs/read_write.c:651 [inline]
__se_sys_write fs/read_write.c:648 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:648
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811edabb88 of 8 bytes by task 13916 on cpu 1:
i_size_read include/linux/fs.h:854 [inline]
filemap_map_pages+0x649/0x9a0 mm/filemap.c:2830
do_fault_around mm/memory.c:3993 [inline]
do_read_fault+0x22f/0x760 mm/memory.c:4027
do_fault mm/memory.c:4160 [inline]
handle_pte_fault mm/memory.c:4400 [inline]
__handle_mm_fault mm/memory.c:4535 [inline]
handle_mm_fault+0x14e9/0x1af0 mm/memory.c:4633
faultin_page mm/gup.c:878 [inline]
__get_user_pages+0xa3d/0x1010 mm/gup.c:1090
populate_vma_page_range mm/gup.c:1423 [inline]
__mm_populate+0x24d/0x340 mm/gup.c:1471
mm_populate include/linux/mm.h:2566 [inline]
vm_mmap_pgoff+0x133/0x170 mm/util.c:511
ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1596
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13916 Comm: syz-executor.2 Not tainted 5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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