KCSAN: data-race in generic_write_end / next_uptodate_page

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4010a528219e Merge tag 'fixes_for_v5.14-rc4' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17533262300000
kernel config: https://syzkaller.appspot.com/x/.config?x=d594b3b1f1ef925f
dashboard link: https://syzkaller.appspot.com/bug?extid=babe32eed987db4bbbd8
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
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+babe32...@syzkaller.appspotmail.com

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

write to 0xffff8881069fa390 of 8 bytes by task 5240 on cpu 0:
i_size_write include/linux/fs.h:871 [inline]
generic_write_end+0x96/0x180 fs/buffer.c:2182
ext4_da_write_end+0x59b/0x730 fs/ext4/inode.c:3110
generic_perform_write+0x22a/0x3c0 mm/filemap.c:3667
ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
call_write_iter include/linux/fs.h:2114 [inline]
new_sync_write fs/read_write.c:518 [inline]
vfs_write+0x69d/0x770 fs/read_write.c:605
ksys_write+0xce/0x180 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:667
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881069fa390 of 8 bytes by task 5242 on cpu 1:
i_size_read include/linux/fs.h:849 [inline]
next_uptodate_page+0x323/0x670 mm/filemap.c:3146
next_map_page mm/filemap.c:3171 [inline]
filemap_map_pages+0x761/0x870 mm/filemap.c:3227
do_fault_around mm/memory.c:4151 [inline]
do_read_fault mm/memory.c:4166 [inline]
do_fault mm/memory.c:4300 [inline]
handle_pte_fault mm/memory.c:4558 [inline]
__handle_mm_fault mm/memory.c:4693 [inline]
handle_mm_fault+0xd83/0x1a50 mm/memory.c:4791
faultin_page mm/gup.c:951 [inline]
__get_user_pages+0x32b/0xbc0 mm/gup.c:1173
populate_vma_page_range mm/gup.c:1506 [inline]
__mm_populate+0x24d/0x380 mm/gup.c:1612
mm_populate include/linux/mm.h:2623 [inline]
vm_mmap_pgoff+0x142/0x1d0 mm/util.c:524
ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1635
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000be9000 -> 0x0000000000bea000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5242 Comm: syz-executor.5 Not tainted 5.14.0-rc3-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.