From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) by kanga.kvack.org (Postfix) with ESMTP id 9B8CD8E0041 for ; Mon, 24 Sep 2018 15:17:40 -0400 (EDT) Received: by mail-pg1-f197.google.com with SMTP id a18-v6so3704233pgn.10 for ; Mon, 24 Sep 2018 12:17:40 -0700 (PDT) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id y1-v6sor15192pgj.247.2018.09.24.12.17.39 for (Google Transport Security); Mon, 24 Sep 2018 12:17:39 -0700 (PDT) Date: Mon, 24 Sep 2018 12:17:34 -0700 (PDT) From: David Rientjes Subject: Re: [patch] mm, thp: always specify ineligible vmas as nh in smaps In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Alexey Dobriyan , Andrew Morton , "Kirill A. Shutemov" , Michal Hocko , linux-kernel@vger.kernel.org, Linux-MM layout , Linux API On Mon, 24 Sep 2018, Vlastimil Babka wrote: > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > > --- a/fs/proc/task_mmu.c > > +++ b/fs/proc/task_mmu.c > > @@ -653,13 +653,23 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) > > #endif > > #endif /* CONFIG_ARCH_HAS_PKEYS */ > > }; > > + unsigned long flags = vma->vm_flags; > > size_t i; > > > > + /* > > + * Disabling thp is possible through both MADV_NOHUGEPAGE and > > + * PR_SET_THP_DISABLE. Both historically used VM_NOHUGEPAGE. Since > > + * the introduction of MMF_DISABLE_THP, however, userspace needs the > > + * ability to detect vmas where thp is not eligible in the same manner. > > + */ > > + if (vma->vm_mm && test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) > > + flags |= VM_NOHUGEPAGE; > > Should it also clear VM_HUGEPAGE? In case MMF_DISABLE_THP overrides a > madvise(MADV_HUGEPAGE)'d vma? (I expect it does?) > Good point, I think that is should because MMF_DISABLE_THP will override VM_HUGEPAGE. It looks like the Documentation file is still referencing both as advise flags and doesn't address PR_SET_THP_DISABLE. Let me send a v2 with a Documentation update and your suggested fix. Thanks Vlastimil! > > + > > seq_puts(m, "VmFlags: "); > > for (i = 0; i < BITS_PER_LONG; i++) { > > if (!mnemonics[i][0]) > > continue; > > - if (vma->vm_flags & (1UL << i)) { > > + if (flags & (1UL << i)) { > > seq_putc(m, mnemonics[i][0]); > > seq_putc(m, mnemonics[i][1]); > > seq_putc(m, ' '); > >