From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx175.postini.com [74.125.245.175]) by kanga.kvack.org (Postfix) with SMTP id 1BF8D6B0031 for ; Mon, 5 Aug 2013 18:06:21 -0400 (EDT) Date: Mon, 5 Aug 2013 15:06:18 -0700 From: Andrew Morton Subject: Re: [patch 3/7] arch: mm: pass userspace fault flag to generic fault handler Message-Id: <20130805150618.47d699f5ce9f42242ee2e7c3@linux-foundation.org> In-Reply-To: <1375549200-19110-4-git-send-email-hannes@cmpxchg.org> References: <1375549200-19110-1-git-send-email-hannes@cmpxchg.org> <1375549200-19110-4-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Michal Hocko , David Rientjes , KAMEZAWA Hiroyuki , azurIt , KOSAKI Motohiro , linux-mm@kvack.org, cgroups@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org On Sat, 3 Aug 2013 12:59:56 -0400 Johannes Weiner 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org