From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751717AbdKFHEm (ORCPT ); Mon, 6 Nov 2017 02:04:42 -0500 Received: from mail-io0-f195.google.com ([209.85.223.195]:54534 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307AbdKFHEl (ORCPT ); Mon, 6 Nov 2017 02:04:41 -0500 X-Google-Smtp-Source: ABhQp+T1rejB+Hso5f44DED4W7HWSlny9tYIrLstGV6J+/RZ87kktp26u48xNhaLv4cMF2ORc+G1O7eN/BPEpPhTalY= MIME-Version: 1.0 In-Reply-To: <20171106033651.172368-1-wangnan0@huawei.com> References: <20171106033651.172368-1-wangnan0@huawei.com> From: Bob Liu Date: Mon, 6 Nov 2017 15:04:40 +0800 Message-ID: Subject: Re: [RFC PATCH] mm, oom_reaper: gather each vma to prevent leaking TLB entry To: Wang Nan Cc: Linux-MM , Linux-Kernel , Bob Liu , Michal Hocko , Andrew Morton , David Rientjes , Ingo Molnar , Roman Gushchin , Konstantin Khlebnikov , Andrea Arcangeli , will.deacon@arm.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 6, 2017 at 11:36 AM, Wang Nan wrote: > tlb_gather_mmu(&tlb, mm, 0, -1) means gathering all virtual memory space. > In this case, tlb->fullmm is true. Some archs like arm64 doesn't flush > TLB when tlb->fullmm is true: > > commit 5a7862e83000 ("arm64: tlbflush: avoid flushing when fullmm == 1"). > CC'ed Will Deacon. > Which makes leaking of tlb entries. For example, when oom_reaper > selects a task and reaps its virtual memory space, another thread > in this task group may still running on another core and access > these already freed memory through tlb entries. > > This patch gather each vma instead of gathering full vm space, > tlb->fullmm is not true. The behavior of oom reaper become similar > to munmapping before do_exit, which should be safe for all archs. > > Signed-off-by: Wang Nan > Cc: Bob Liu > Cc: Michal Hocko > Cc: Andrew Morton > Cc: Michal Hocko > Cc: David Rientjes > Cc: Ingo Molnar > Cc: Roman Gushchin > Cc: Konstantin Khlebnikov > Cc: Andrea Arcangeli > --- > mm/oom_kill.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index dee0f75..18c5b35 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -532,7 +532,6 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) > */ > set_bit(MMF_UNSTABLE, &mm->flags); > > - tlb_gather_mmu(&tlb, mm, 0, -1); > for (vma = mm->mmap ; vma; vma = vma->vm_next) { > if (!can_madv_dontneed_vma(vma)) > continue; > @@ -547,11 +546,13 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) > * we do not want to block exit_mmap by keeping mm ref > * count elevated without a good reason. > */ > - if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED)) > + if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED)) { > + tlb_gather_mmu(&tlb, mm, vma->vm_start, vma->vm_end); > unmap_page_range(&tlb, vma, vma->vm_start, vma->vm_end, > NULL); > + tlb_finish_mmu(&tlb, vma->vm_start, vma->vm_end); > + } > } > - tlb_finish_mmu(&tlb, 0, -1); > pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", > task_pid_nr(tsk), tsk->comm, > K(get_mm_counter(mm, MM_ANONPAGES)), From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f197.google.com (mail-io0-f197.google.com [209.85.223.197]) by kanga.kvack.org (Postfix) with ESMTP id C8FA76B0038 for ; Mon, 6 Nov 2017 02:04:41 -0500 (EST) Received: by mail-io0-f197.google.com with SMTP id n33so20790710ioi.7 for ; Sun, 05 Nov 2017 23:04:41 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j91sor6208950iod.276.2017.11.05.23.04.40 for (Google Transport Security); Sun, 05 Nov 2017 23:04:40 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20171106033651.172368-1-wangnan0@huawei.com> References: <20171106033651.172368-1-wangnan0@huawei.com> From: Bob Liu Date: Mon, 6 Nov 2017 15:04:40 +0800 Message-ID: Subject: Re: [RFC PATCH] mm, oom_reaper: gather each vma to prevent leaking TLB entry Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Wang Nan Cc: Linux-MM , Linux-Kernel , Bob Liu , Michal Hocko , Andrew Morton , David Rientjes , Ingo Molnar , Roman Gushchin , Konstantin Khlebnikov , Andrea Arcangeli , will.deacon@arm.com On Mon, Nov 6, 2017 at 11:36 AM, Wang Nan wrote: > tlb_gather_mmu(&tlb, mm, 0, -1) means gathering all virtual memory space. > In this case, tlb->fullmm is true. Some archs like arm64 doesn't flush > TLB when tlb->fullmm is true: > > commit 5a7862e83000 ("arm64: tlbflush: avoid flushing when fullmm == 1"). > CC'ed Will Deacon. > Which makes leaking of tlb entries. For example, when oom_reaper > selects a task and reaps its virtual memory space, another thread > in this task group may still running on another core and access > these already freed memory through tlb entries. > > This patch gather each vma instead of gathering full vm space, > tlb->fullmm is not true. The behavior of oom reaper become similar > to munmapping before do_exit, which should be safe for all archs. > > Signed-off-by: Wang Nan > Cc: Bob Liu > Cc: Michal Hocko > Cc: Andrew Morton > Cc: Michal Hocko > Cc: David Rientjes > Cc: Ingo Molnar > Cc: Roman Gushchin > Cc: Konstantin Khlebnikov > Cc: Andrea Arcangeli > --- > mm/oom_kill.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index dee0f75..18c5b35 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -532,7 +532,6 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) > */ > set_bit(MMF_UNSTABLE, &mm->flags); > > - tlb_gather_mmu(&tlb, mm, 0, -1); > for (vma = mm->mmap ; vma; vma = vma->vm_next) { > if (!can_madv_dontneed_vma(vma)) > continue; > @@ -547,11 +546,13 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) > * we do not want to block exit_mmap by keeping mm ref > * count elevated without a good reason. > */ > - if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED)) > + if (vma_is_anonymous(vma) || !(vma->vm_flags & VM_SHARED)) { > + tlb_gather_mmu(&tlb, mm, vma->vm_start, vma->vm_end); > unmap_page_range(&tlb, vma, vma->vm_start, vma->vm_end, > NULL); > + tlb_finish_mmu(&tlb, vma->vm_start, vma->vm_end); > + } > } > - tlb_finish_mmu(&tlb, 0, -1); > pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", > task_pid_nr(tsk), tsk->comm, > K(get_mm_counter(mm, MM_ANONPAGES)), -- 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