From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id BBDFA1A0202 for ; Mon, 11 Jan 2016 21:07:07 +1100 (AEDT) Received: from localhost by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 11 Jan 2016 20:07:05 +1000 Received: from d23relay06.au.ibm.com (d23relay06.au.ibm.com [9.185.63.219]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id B40FA2CE8054 for ; Mon, 11 Jan 2016 21:07:00 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay06.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0BA6cER23003156 for ; Mon, 11 Jan 2016 21:06:51 +1100 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0BA6MqZ010132 for ; Mon, 11 Jan 2016 21:06:23 +1100 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, Hugh Dickins , Andrew Morton , Laurent Dufour Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, "Aneesh Kumar K.V" Subject: [PATCH] mm/powerpc: Fix _PAGE_PTE breaking swapoff Date: Mon, 11 Jan 2016 15:35:50 +0530 Message-Id: <1452506750-2355-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , When converting a swp_entry_t to pte, we need to add _PAGE_PTE, because we later compare the pte with linux page table entries to find a matching pte. We do set _PAGE_PTE on pte entries on linux page table even if it is a swap entry. So add them when converting swp_entry_t to pte_t The stack trace can be anywhere below try_to_unuse() in mm/swapfile.c, since swapoff is circling around and around that function, reading from each used swap block into a page, then trying to find where that page belongs, looking at every non-file pte of every mm that ever swapped. Reported-by: Hugh Dickins Suggested-by: Hugh Dickins Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/include/asm/book3s/64/pgtable.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 03c1a5a21c0c..48edcd8fbc4f 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -158,9 +158,14 @@ static inline void pgd_set(pgd_t *pgdp, unsigned long val) #define __swp_entry(type, offset) ((swp_entry_t) { \ ((type) << _PAGE_BIT_SWAP_TYPE) \ | ((offset) << PTE_RPN_SHIFT) }) - -#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) }) -#define __swp_entry_to_pte(x) __pte((x).val) +/* + * swp_entry_t should be arch independent. We build a swp_entry_t from + * swap type and offset we get from swap and convert that to pte to + * find a matching pte in linux page table. + * Clear bits not found in swap entries here + */ +#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) #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY #define _PAGE_SWP_SOFT_DIRTY (1UL << (SWP_TYPE_BITS + _PAGE_BIT_SWAP_TYPE)) -- 2.5.0