e93ab401da
dquot_scan_active() can race with quota deactivation in
quota_release_workfn() like:
CPU0 (quota_release_workfn) CPU1 (dquot_scan_active)
============================== ==============================
spin_lock(&dq_list_lock);
list_replace_init(
&releasing_dquots, &rls_head);
/* dquot X on rls_head,
dq_count == 0,
DQ_ACTIVE_B still set */
spin_unlock(&dq_list_lock);
synchronize_srcu(&dquot_srcu);
spin_lock(&dq_list_lock);
list_for_each_entry(dquot,
&inuse_list, dq_inuse) {
/* finds dquot X */
dquot_active(X) -> true
atomic_inc(&X->dq_count);
}
spin_unlock(&dq_list_lock);
spin_lock(&dq_list_lock);
dquot = list_first_entry(&rls_head);
WARN_ON_ONCE(atomic_read(&dquot->dq_count));
The problem is not only a cosmetic one as under memory pressure the
caller of dquot_scan_active() can end up working on freed dquot.
Fix the problem by making sure the dquot is removed from releasing list
when we acquire a reference to it.
Fixes:
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|---|---|---|
| .. | ||
| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| cxl | ||
| drm | ||
| dt-bindings | ||
| hyperv | ||
| keys | ||
| kunit | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| rv | ||
| scsi | ||
| soc | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| ufs | ||
| vdso | ||
| video | ||
| xen | ||
| Kbuild | ||