linux-kernel - [syzbot] [ext4?] KCSAN: data-race in __filemap_add_folio / sync

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Message-ID: <66ee8110.050a0220.3195df.003f.GAE@google.com>
Date: Sat, 21 Sep 2024 01:17:20 -0700
From: syzbot <syzbot+cf1fa2a387833ee7edec@...kaller.appspotmail.com>
To: jack@...e.com, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: [syzbot] [ext4?] KCSAN: data-race in __filemap_add_folio / sync_bdevs (2)

Hello,

syzbot found the following issue on:

HEAD commit:    1868f9d0260e Merge tag 'for-linux-6.12-ofs1' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1067ff00580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3b3c9c7ae5fde27e
dashboard link: https://syzkaller.appspot.com/bug?extid=cf1fa2a387833ee7edec
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/16d776046b21/disk-1868f9d0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2b09f78f002c/vmlinux-1868f9d0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7705cc7035ce/bzImage-1868f9d0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf1fa2a387833ee7edec@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __filemap_add_folio / sync_bdevs

read-write to 0xffff8881004c24b0 of 8 bytes by task 2929 on cpu 0:
 __filemap_add_folio+0x439/0x710 mm/filemap.c:920
 filemap_add_folio+0x9c/0x1b0 mm/filemap.c:972
 __filemap_get_folio+0x2f1/0x5b0 mm/filemap.c:1960
 grow_dev_folio fs/buffer.c:1043 [inline]
 grow_buffers fs/buffer.c:1109 [inline]
 __getblk_slow fs/buffer.c:1135 [inline]
 bdev_getblk+0x173/0x3b0 fs/buffer.c:1437
 __getblk include/linux/buffer_head.h:380 [inline]
 jbd2_journal_get_descriptor_buffer+0xcf/0x210 fs/jbd2/journal.c:974
 jbd2_journal_commit_transaction+0xc03/0x33e0 fs/jbd2/commit.c:610
 kjournald2+0x20b/0x3c0 fs/jbd2/journal.c:201
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881004c24b0 of 8 bytes by task 1695 on cpu 1:
 sync_bdevs+0xd6/0x260 block/bdev.c:1228
 ksys_sync+0x8c/0xe0 fs/sync.c:106
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 x64_sys_call+0x2693/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:163
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000a25 -> 0x0000000000000a26

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 1695 Comm: syz.0.18383 Tainted: G        W          6.11.0-syzkaller-07462-g1868f9d0260e #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================


---
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