From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x235.google.com (mail-pf0-x235.google.com [IPv6:2607:f8b0:400e:c00::235]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 69AEA1A08A5 for ; Sun, 10 Jan 2016 11:51:12 +1100 (AEDT) Received: by mail-pf0-x235.google.com with SMTP id q63so27699078pfb.1 for ; Sat, 09 Jan 2016 16:51:12 -0800 (PST) Date: Sat, 9 Jan 2016 16:50:53 -0800 (PST) From: Hugh Dickins To: "Aneesh Kumar K.V" cc: Andrew Morton , Michael Ellerman , Laurent Dufour , linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org Subject: [PATCH next] powerpc/mm: fix _PAGE_PTE breaking swapoff Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Swapoff after swapping hangs on the G5. That's because the _PAGE_PTE bit, added by set_pte_at(), is not expected by swapoff: so swap ptes cannot be recognized. I'm not sure whether a swap pte should or should not have _PAGE_PTE set: this patch assumes not, and fixes set_pte_at() to set _PAGE_PTE only on present entries. But if that's wrong, a reasonable alternative would be to #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) & ~_PAGE_PTE }) #define __swp_entry_to_pte(x) __pte((x).val | _PAGE_PTE) Signed-off-by: Hugh Dickins --- arch/powerpc/mm/pgtable.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- 4.4-next/arch/powerpc/mm/pgtable.c 2016-01-06 11:54:01.477512251 -0800 +++ linux/arch/powerpc/mm/pgtable.c 2016-01-09 13:51:15.793485717 -0800 @@ -180,9 +180,10 @@ void set_pte_at(struct mm_struct *mm, un VM_WARN_ON((pte_val(*ptep) & (_PAGE_PRESENT | _PAGE_USER)) == (_PAGE_PRESENT | _PAGE_USER)); /* - * Add the pte bit when tryint set a pte + * Add the pte bit when setting a pte (not a swap entry) */ - pte = __pte(pte_val(pte) | _PAGE_PTE); + if (pte_val(pte) & _PAGE_PRESENT) + pte = __pte(pte_val(pte) | _PAGE_PTE); /* Note: mm->context.id might not yet have been assigned as * this context might not have been activated yet when this