On Fri, Sep 18, 2026 at 04:40 PM Jiayuan Chen <[email protected]> wrote: > @@ -489,59 +490,108 @@ static vm_fault_t arena_vm_fault(struct vm_fault *vmf) > kbase = bpf_arena_get_kern_vm_start(arena); > kaddr = kbase + (u32)(vmf->address); > > - if (raw_res_spin_lock_irqsave(&arena->spinlock, flags)) > + page = vmalloc_to_page((void *)kaddr); > + if (!page && !(arena->map.map_flags & BPF_F_SEGV_ON_FAULT)) { > + /* > + * Preallocate outside the lock so the allocation can sleep and > + * reclaim, which the non-blocking allocator under > + * arena->spinlock cannot. __GFP_RETRY_MAYFAIL: reclaim, but > + * never OOM-kill in the map's memcg, which need not be the > + * faulting task's. On failure, fallthrough: the locked > + * recheck below picks up a page a concurrent allocator may > + * have installed meanwhile, and otherwise the non-blocking > + * fallback fails and we return VM_FAULT_SIGBUS. Not > + * VM_FAULT_OOM: nothing ran the OOM killer, an d the fault path > + * would just retry it forever. > + */
I asked for one line comment. This block and the one in !new_page branch below repeat the commit log. Trim both to a sentence or two. pw-bot: cr
