0c7273e494
The background inode inactivation can attached dquots to inodes, but this can race with a foreground quotacheck failure that leads to disabling quotas and freeing the mp->m_quotainfo structure. The background inode inactivation then tries to allocate a quota, tries to dereference mp->m_quotainfo, and crashes like so: XFS (loop1): Quotacheck: Unsuccessful (Error -5): Disabling quotas. xfs filesystem being mounted at /root/syzkaller.qCVHXV/0/file0 supports timestamps until 2038 (0x7fffffff) BUG: kernel NULL pointer dereference, address: 00000000000002a8 .... CPU: 0 PID: 161 Comm: kworker/0:4 Not tainted 6.2.0-c9c3395d5e3d #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: xfs-inodegc/loop1 xfs_inodegc_worker RIP: 0010:xfs_dquot_alloc+0x95/0x1e0 .... Call Trace: <TASK> xfs_qm_dqread+0x46/0x440 xfs_qm_dqget_inode+0x154/0x500 xfs_qm_dqattach_one+0x142/0x3c0 xfs_qm_dqattach_locked+0x14a/0x170 xfs_qm_dqattach+0x52/0x80 xfs_inactive+0x186/0x340 xfs_inodegc_worker+0xd3/0x430 process_one_work+0x3b1/0x960 worker_thread+0x52/0x660 kthread+0x161/0x1a0 ret_from_fork+0x29/0x50 </TASK> .... Prevent this race by flushing all the queued background inode inactivations pending before purging all the cached dquots when quotacheck fails. Reported-by: Pengfei Xu <pengfei.xu@intel.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.