On Mon, Aug 05, 2013 at 03:06:18PM -0700, Andrew Morton wrote: > On Sat, 3 Aug 2013 12:59:56 -0400 Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > > Unlike global OOM handling, memory cgroup code will invoke the OOM > > killer in any OOM situation because it has no way of telling faults > > occuring in kernel context - which could be handled more gracefully - > > from user-triggered faults. > > > > Pass a flag that identifies faults originating in user space from the > > architecture-specific fault handlers to generic code so that memcg OOM > > handling can be improved. > > arch/arm64/mm/fault.c has changed. Here's what I came up with: > > --- a/arch/arm64/mm/fault.c~arch-mm-pass-userspace-fault-flag-to-generic-fault-handler > +++ a/arch/arm64/mm/fault.c > @@ -199,13 +199,6 @@ static int __kprobes do_page_fault(unsig > unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC; > unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; > > - if (esr & ESR_LNX_EXEC) { > - vm_flags = VM_EXEC; > - } else if ((esr & ESR_WRITE) && !(esr & ESR_CM)) { > - vm_flags = VM_WRITE; > - mm_flags |= FAULT_FLAG_WRITE; > - } > - > tsk = current; > mm = tsk->mm; > > @@ -220,6 +213,16 @@ static int __kprobes do_page_fault(unsig > if (in_atomic() || !mm) > goto no_context; > > + if (user_mode(regs)) > + mm_flags |= FAULT_FLAG_USER; > + > + if (esr & ESR_LNX_EXEC) { > + vm_flags = VM_EXEC; > + } else if ((esr & ESR_WRITE) && !(esr & ESR_CM)) { > + vm_flags = VM_WRITE; > + mm_flags |= FAULT_FLAG_WRITE; > + } > + > /* > * As per x86, we may deadlock here. However, since the kernel only > * validly references user space from well defined areas of the code, > > But I'm not terribly confident in it. It looks good to me. They added the vm_flags but they are not used any earlier than the mm_flags (__do_page_fault), which I moved to the same location as you did in this fixup. Thanks! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>