linux-kernel - Re: [syzbot] [mm?] KCSAN: data-race in generic_fillattr / shmem

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Message-ID: <0000000000007766900621984c6d@google.com>
Date: Sun, 08 Sep 2024 02:31:01 -0700
From: syzbot <syzbot+702361cf7e3d95758761@...kaller.appspotmail.com>
To: aha310510@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] KCSAN: data-race in generic_fillattr / shmem_mknod (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KCSAN: data-race in jbd2_journal_dirty_metadata / jbd2_journal_dirty_metadata

==================================================================
BUG: KCSAN: data-race in jbd2_journal_dirty_metadata / jbd2_journal_dirty_metadata

write to 0xffff88810062608c of 4 bytes by task 7571 on cpu 1:
 jbd2_journal_dirty_metadata+0x346/0x6d0 fs/jbd2/transaction.c:1560
 __ext4_handle_dirty_metadata+0xe6/0x470 fs/ext4/ext4_jbd2.c:354
 __ext4_new_inode+0x11fd/0x2200 fs/ext4/ialloc.c:1124
 ext4_create+0x172/0x2f0 fs/ext4/namei.c:2832
 lookup_open fs/namei.c:3578 [inline]
 open_last_lookups fs/namei.c:3647 [inline]
 path_openat+0xdbc/0x1f00 fs/namei.c:3883
 do_filp_open+0xf7/0x200 fs/namei.c:3913
 do_sys_openat2+0xab/0x120 fs/open.c:1416
 do_sys_open fs/open.c:1431 [inline]
 __do_sys_open fs/open.c:1439 [inline]
 __se_sys_open fs/open.c:1435 [inline]
 __x64_sys_open+0xe6/0x110 fs/open.c:1435
 x64_sys_call+0x1321/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:3
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

read to 0xffff88810062608c of 4 bytes by task 7575 on cpu 0:
 jbd2_journal_dirty_metadata+0xff/0x6d0 fs/jbd2/transaction.c:1516
 __ext4_handle_dirty_metadata+0xe6/0x470 fs/ext4/ext4_jbd2.c:354
 __ext4_new_inode+0x11fd/0x2200 fs/ext4/ialloc.c:1124
 ext4_symlink+0x242/0x5a0 fs/ext4/namei.c:3391
 vfs_symlink+0xca/0x1d0 fs/namei.c:4568
 do_symlinkat+0xe3/0x340 fs/namei.c:4594
 __do_sys_symlinkat fs/namei.c:4610 [inline]
 __se_sys_symlinkat fs/namei.c:4607 [inline]
 __x64_sys_symlinkat+0x5e/0x70 fs/namei.c:4607
 x64_sys_call+0x1dda/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:267
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7575 Comm: syz-executor.5 Not tainted 6.11.0-rc6-syzkaller-00326-gd1f2d51b711a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================


Tested on:

commit:         d1f2d51b Merge tag 'clk-fixes-for-linus' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134f8877980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e81d40b0108ea8fe
dashboard link: https://syzkaller.appspot.com/bug?extid=702361cf7e3d95758761
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15538877980000