KCSAN: data-race in __unmap_and_move / delete_from_page_cache_batch

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4429f14a Merge tag 'block-5.10-2020-11-07' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16178062500000
kernel config: https://syzkaller.appspot.com/x/.config?x=76dfc991796328d4
dashboard link: https://syzkaller.appspot.com/bug?extid=0824a71495e6ee548878
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

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+0824a7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __unmap_and_move / delete_from_page_cache_batch

write to 0xffffea00043bf358 of 8 bytes by task 17945 on cpu 1:
page_cache_delete_batch mm/filemap.c:327 [inline]
delete_from_page_cache_batch+0x36b/0x800 mm/filemap.c:358
truncate_inode_pages_range+0x482/0xf20 mm/truncate.c:366
truncate_inode_pages mm/truncate.c:476 [inline]
truncate_pagecache+0x4f/0x70 mm/truncate.c:839
ext4_setattr+0xaf9/0xf60 fs/ext4/inode.c:5486
notify_change+0x7b3/0xa50 fs/attr.c:336
do_truncate+0xe0/0x120 fs/open.c:64
handle_truncate fs/namei.c:2910 [inline]
do_open fs/namei.c:3256 [inline]
path_openat+0x1a37/0x20a0 fs/namei.c:3369
do_filp_open+0xbd/0x1d0 fs/namei.c:3396
do_sys_openat2+0xa3/0x240 fs/open.c:1168
do_sys_open fs/open.c:1184 [inline]
__do_sys_openat fs/open.c:1200 [inline]
__se_sys_openat fs/open.c:1195 [inline]
__x64_sys_openat+0xef/0x110 fs/open.c:1195
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffea00043bf358 of 8 bytes by task 17940 on cpu 0:
__PageMovable include/linux/page-flags.h:490 [inline]
__unmap_and_move+0x42/0x690 mm/migrate.c:1025
unmap_and_move+0x130/0x860 mm/migrate.c:1197
migrate_pages+0x24b/0xb30 mm/migrate.c:1453
do_mbind mm/mempolicy.c:1351 [inline]
kernel_mbind+0xe7b/0xff0 mm/mempolicy.c:1472
__do_sys_mbind mm/mempolicy.c:1479 [inline]
__se_sys_mbind mm/mempolicy.c:1475 [inline]
__x64_sys_mbind+0x74/0x80 mm/mempolicy.c:1475
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: 0 PID: 17940 Comm: syz-executor.2 Not tainted 5.10.0-rc2-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.