On Thu, Mar 30, 2023 at 3:27 AM 'Dave Chinner' via syzkaller-bugs <syzkaller-bugs@xxxxxxxxxxxxxxxx> wrote: > > On Tue, Mar 28, 2023 at 09:08:01PM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 1e760fa3596e Merge tag 'gfs2-v6.3-rc3-fix' of git://git.ke.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=16f83651c80000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=acdb62bf488a8fe5 > > dashboard link: https://syzkaller.appspot.com/bug?extid=0c383e46e9b4827b01b1 > > compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/17229b6e6fe0/disk-1e760fa3.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/69b5d310fba0/vmlinux-1e760fa3.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/0c65624aace9/bzImage-1e760fa3.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+0c383e46e9b4827b01b1@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ------------[ cut here ]------------ > > WARNING: CPU: 1 PID: 24101 at fs/xfs/libxfs/xfs_bmap.c:660 xfs_bmap_extents_to_btree+0xe1b/0x1190 > > Allocation got an unexpected ENOSPC when it was supposed to have a > valid reservation for the space. Likely because of an inconsistency > that had been induced into the filesystem where superblock space > accounting doesn't exactly match the AG space accounting and/or the > tracked free space. > > Given this is a maliciously corrupted filesystem image, this sort of > warning is expected and there's probably nothing we can do to avoid > it short of a full filesystem verification pass during mount. > That's not a viable solution, so I think we should just ignore > syzbot when it generates this sort of warning.... If it's not a warning about a kernel bug, then WARN_ON should probably be replaced by some more suitable reporting mechanism. Kernel coding style document explicitly says: "WARN*() must not be used for a condition that is expected to trigger easily, for example, by user space actions. pr_warn_once() is a possible alternative, if you need to notify the user of a problem." https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=1e760fa3596e8c7f08412712c168288b79670d78#n1223 -- Aleksandr > > i.e. we actually want this warning to be issued if it happens in > normal production situations, but given that it's relatively trivial > to create an inconsistent filesystem image that can trigger this we > should just ignore it when it is generated by such means. > > -Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx >
