From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758535AbaD2VVo (ORCPT ); Tue, 29 Apr 2014 17:21:44 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:39927 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756357AbaD2VVk (ORCPT ); Tue, 29 Apr 2014 17:21:40 -0400 From: John Stultz To: LKML Cc: John Stultz , Andrew Morton , Android Kernel Team , Johannes Weiner , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dmitry Adamushko , Neil Brown , Andrea Arcangeli , Mike Hommey , Taras Glek , Jan Kara , KOSAKI Motohiro , Michel Lespinasse , Minchan Kim , Keith Packard , "linux-mm@kvack.org" Subject: [PATCH 3/4] MADV_VOLATILE: Add purged page detection on setting memory non-volatile Date: Tue, 29 Apr 2014 14:21:22 -0700 Message-Id: <1398806483-19122-4-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1398806483-19122-1-git-send-email-john.stultz@linaro.org> References: <1398806483-19122-1-git-send-email-john.stultz@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Users of volatile ranges will need to know if memory was discarded. This patch adds the purged state tracking required to inform userland when it marks memory as non-volatile that some memory in that range was purged and needs to be regenerated. This simplified implementation which uses some of the logic from Minchan's earlier efforts, so credit to Minchan for his work. Cc: Andrew Morton Cc: Android Kernel Team Cc: Johannes Weiner Cc: Robert Love Cc: Mel Gorman Cc: Hugh Dickins Cc: Dave Hansen Cc: Rik van Riel Cc: Dmitry Adamushko Cc: Neil Brown Cc: Andrea Arcangeli Cc: Mike Hommey Cc: Taras Glek Cc: Jan Kara Cc: KOSAKI Motohiro Cc: Michel Lespinasse Cc: Minchan Kim Cc: Keith Packard Cc: linux-mm@kvack.org Acked-by: Jan Kara Signed-off-by: John Stultz --- include/linux/swap.h | 5 +++ include/linux/swapops.h | 10 ++++++ mm/mvolatile.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 102 insertions(+) diff --git a/include/linux/swap.h b/include/linux/swap.h index a32c3da..3abc977 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -55,6 +55,7 @@ enum { * 1< #include #include +#include +#include #include "internal.h" +struct mvolatile_walker { + struct vm_area_struct *vma; + int page_was_purged; +}; + + +/** + * mvolatile_check_purged_pte - Checks ptes for purged pages + * @pmd: pmd to walk + * @addr: starting address + * @end: end address + * @walk: mm_walk ptr (contains ptr to mvolatile_walker) + * + * Iterates over the ptes in the pmd checking if they have + * purged swap entries. + * + * Sets the mvolatile_walker.page_was_purged to 1 if any were purged, + * and clears the purged pte swp entries (since the pages are no + * longer volatile, we don't want future accesses to SIGBUS). + */ +static int mvolatile_check_purged_pte(pmd_t *pmd, unsigned long addr, + unsigned long end, struct mm_walk *walk) +{ + struct mvolatile_walker *vw = walk->private; + pte_t *pte; + spinlock_t *ptl; + + if (pmd_trans_huge(*pmd)) + return 0; + if (pmd_trans_unstable(pmd)) + return 0; + + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + for (; addr != end; pte++, addr += PAGE_SIZE) { + if (!pte_present(*pte)) { + swp_entry_t mvolatile_entry = pte_to_swp_entry(*pte); + + if (unlikely(is_purged_entry(mvolatile_entry))) { + + vw->page_was_purged = 1; + + /* clear the pte swp entry */ + flush_cache_page(vw->vma, addr, pte_pfn(*pte)); + ptep_clear_flush(vw->vma, addr, pte); + } + } + } + pte_unmap_unlock(pte - 1, ptl); + cond_resched(); + + return 0; +} + + +/** + * mvolatile_check_purged - Sets up a mm_walk to check for purged pages + * @vma: ptr to vma we're starting with + * @start: start address to walk + * @end: end address of walk + * + * Sets up and calls wa_page_range() to check for purge pages. + * + * Returns 1 if pages in the range were purged, 0 otherwise. + */ +static int mvolatile_check_purged(struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ + struct mvolatile_walker vw; + struct mm_walk mvolatile_walk = { + .pmd_entry = mvolatile_check_purged_pte, + .mm = vma->vm_mm, + .private = &vw, + }; + vw.page_was_purged = 0; + vw.vma = vma; + + walk_page_range(start, end, &mvolatile_walk); + + return vw.page_was_purged; +} + /** * madvise_volatile - Marks or clears VMAs in the range (start-end) as VM_VOLATILE @@ -140,6 +224,9 @@ int madvise_volatile(int mode, unsigned long start, unsigned long end) break; vma = vma->vm_next; } + + if (!ret && (mode == MADV_NONVOLATILE)) + ret = mvolatile_check_purged(vma, orig_start, end); out: up_write(&mm->mmap_sem); -- 1.9.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by kanga.kvack.org (Postfix) with ESMTP id 853D26B003B for ; Tue, 29 Apr 2014 17:21:41 -0400 (EDT) Received: by mail-pa0-f51.google.com with SMTP id fb1so836438pad.10 for ; Tue, 29 Apr 2014 14:21:41 -0700 (PDT) Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) by mx.google.com with ESMTPS id fn10si14302971pad.320.2014.04.29.14.21.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 29 Apr 2014 14:21:40 -0700 (PDT) Received: by mail-pd0-f182.google.com with SMTP id v10so715958pde.41 for ; Tue, 29 Apr 2014 14:21:40 -0700 (PDT) From: John Stultz Subject: [PATCH 3/4] MADV_VOLATILE: Add purged page detection on setting memory non-volatile Date: Tue, 29 Apr 2014 14:21:22 -0700 Message-Id: <1398806483-19122-4-git-send-email-john.stultz@linaro.org> In-Reply-To: <1398806483-19122-1-git-send-email-john.stultz@linaro.org> References: <1398806483-19122-1-git-send-email-john.stultz@linaro.org> Sender: owner-linux-mm@kvack.org List-ID: To: LKML Cc: John Stultz , Andrew Morton , Android Kernel Team , Johannes Weiner , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dmitry Adamushko , Neil Brown , Andrea Arcangeli , Mike Hommey , Taras Glek , Jan Kara , KOSAKI Motohiro , Michel Lespinasse , Minchan Kim , Keith Packard , "linux-mm@kvack.org" Users of volatile ranges will need to know if memory was discarded. This patch adds the purged state tracking required to inform userland when it marks memory as non-volatile that some memory in that range was purged and needs to be regenerated. This simplified implementation which uses some of the logic from Minchan's earlier efforts, so credit to Minchan for his work. Cc: Andrew Morton Cc: Android Kernel Team Cc: Johannes Weiner Cc: Robert Love Cc: Mel Gorman Cc: Hugh Dickins Cc: Dave Hansen Cc: Rik van Riel Cc: Dmitry Adamushko Cc: Neil Brown Cc: Andrea Arcangeli Cc: Mike Hommey Cc: Taras Glek Cc: Jan Kara Cc: KOSAKI Motohiro Cc: Michel Lespinasse Cc: Minchan Kim Cc: Keith Packard Cc: linux-mm@kvack.org Acked-by: Jan Kara Signed-off-by: John Stultz --- include/linux/swap.h | 5 +++ include/linux/swapops.h | 10 ++++++ mm/mvolatile.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 102 insertions(+) diff --git a/include/linux/swap.h b/include/linux/swap.h index a32c3da..3abc977 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -55,6 +55,7 @@ enum { * 1< #include #include +#include +#include #include "internal.h" +struct mvolatile_walker { + struct vm_area_struct *vma; + int page_was_purged; +}; + + +/** + * mvolatile_check_purged_pte - Checks ptes for purged pages + * @pmd: pmd to walk + * @addr: starting address + * @end: end address + * @walk: mm_walk ptr (contains ptr to mvolatile_walker) + * + * Iterates over the ptes in the pmd checking if they have + * purged swap entries. + * + * Sets the mvolatile_walker.page_was_purged to 1 if any were purged, + * and clears the purged pte swp entries (since the pages are no + * longer volatile, we don't want future accesses to SIGBUS). + */ +static int mvolatile_check_purged_pte(pmd_t *pmd, unsigned long addr, + unsigned long end, struct mm_walk *walk) +{ + struct mvolatile_walker *vw = walk->private; + pte_t *pte; + spinlock_t *ptl; + + if (pmd_trans_huge(*pmd)) + return 0; + if (pmd_trans_unstable(pmd)) + return 0; + + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + for (; addr != end; pte++, addr += PAGE_SIZE) { + if (!pte_present(*pte)) { + swp_entry_t mvolatile_entry = pte_to_swp_entry(*pte); + + if (unlikely(is_purged_entry(mvolatile_entry))) { + + vw->page_was_purged = 1; + + /* clear the pte swp entry */ + flush_cache_page(vw->vma, addr, pte_pfn(*pte)); + ptep_clear_flush(vw->vma, addr, pte); + } + } + } + pte_unmap_unlock(pte - 1, ptl); + cond_resched(); + + return 0; +} + + +/** + * mvolatile_check_purged - Sets up a mm_walk to check for purged pages + * @vma: ptr to vma we're starting with + * @start: start address to walk + * @end: end address of walk + * + * Sets up and calls wa_page_range() to check for purge pages. + * + * Returns 1 if pages in the range were purged, 0 otherwise. + */ +static int mvolatile_check_purged(struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ + struct mvolatile_walker vw; + struct mm_walk mvolatile_walk = { + .pmd_entry = mvolatile_check_purged_pte, + .mm = vma->vm_mm, + .private = &vw, + }; + vw.page_was_purged = 0; + vw.vma = vma; + + walk_page_range(start, end, &mvolatile_walk); + + return vw.page_was_purged; +} + /** * madvise_volatile - Marks or clears VMAs in the range (start-end) as VM_VOLATILE @@ -140,6 +224,9 @@ int madvise_volatile(int mode, unsigned long start, unsigned long end) break; vma = vma->vm_next; } + + if (!ret && (mode == MADV_NONVOLATILE)) + ret = mvolatile_check_purged(vma, orig_start, end); out: up_write(&mm->mmap_sem); -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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