From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932428Ab3JIRdT (ORCPT ); Wed, 9 Oct 2013 13:33:19 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56486 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932371Ab3JIRdP (ORCPT ); Wed, 9 Oct 2013 13:33:15 -0400 Date: Wed, 9 Oct 2013 10:31:43 -0700 From: tip-bot for Mel Gorman Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, hannes@cmpxchg.org, riel@redhat.com, aarcange@redhat.com, srikar@linux.vnet.ibm.com, mgorman@suse.de, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, hannes@cmpxchg.org, riel@redhat.com, aarcange@redhat.com, srikar@linux.vnet.ibm.com, mgorman@suse.de, tglx@linutronix.de In-Reply-To: <1381141781-10992-48-git-send-email-mgorman@suse.de> References: <1381141781-10992-48-git-send-email-mgorman@suse.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] mm: numa: Do not batch handle PMD pages Git-Commit-ID: 0f19c17929c952c6f0966d93ab05558e7bf814cc X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Wed, 09 Oct 2013 10:31:50 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 0f19c17929c952c6f0966d93ab05558e7bf814cc Gitweb: http://git.kernel.org/tip/0f19c17929c952c6f0966d93ab05558e7bf814cc Author: Mel Gorman AuthorDate: Mon, 7 Oct 2013 11:29:25 +0100 Committer: Ingo Molnar CommitDate: Wed, 9 Oct 2013 14:47:55 +0200 mm: numa: Do not batch handle PMD pages With the THP migration races closed it is still possible to occasionally see corruption. The problem is related to handling PMD pages in batch. When a page fault is handled it can be assumed that the page being faulted will also be flushed from the TLB. The same flushing does not happen when handling PMD pages in batch. Fixing is straight forward but there are a number of reasons not to 1. Multiple TLB flushes may have to be sent depending on what pages get migrated 2. The handling of PMDs in batch means that faults get accounted to the task that is handling the fault. While care is taken to only mark PMDs where the last CPU and PID match it can still have problems due to PID truncation when matching PIDs. 3. Batching on the PMD level may reduce faults but setting pmd_numa requires taking a heavy lock that can contend with THP migration and handling the fault requires the release/acquisition of the PTL for every page migrated. It's still pretty heavy. PMD batch handling is not something that people ever have been happy with. This patch removes it and later patches will deal with the additional fault overhead using more installigent migrate rate adaption. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Srikar Dronamraju Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1381141781-10992-48-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar --- mm/memory.c | 101 ++-------------------------------------------------------- mm/mprotect.c | 47 ++------------------------- 2 files changed, 4 insertions(+), 144 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index eba846b..9898eeb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3606,103 +3606,6 @@ out: return 0; } -/* NUMA hinting page fault entry point for regular pmds */ -#ifdef CONFIG_NUMA_BALANCING -static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long addr, pmd_t *pmdp) -{ - pmd_t pmd; - pte_t *pte, *orig_pte; - unsigned long _addr = addr & PMD_MASK; - unsigned long offset; - spinlock_t *ptl; - bool numa = false; - int last_cpupid; - - spin_lock(&mm->page_table_lock); - pmd = *pmdp; - if (pmd_numa(pmd)) { - set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd)); - numa = true; - } - spin_unlock(&mm->page_table_lock); - - if (!numa) - return 0; - - /* we're in a page fault so some vma must be in the range */ - BUG_ON(!vma); - BUG_ON(vma->vm_start >= _addr + PMD_SIZE); - offset = max(_addr, vma->vm_start) & ~PMD_MASK; - VM_BUG_ON(offset >= PMD_SIZE); - orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl); - pte += offset >> PAGE_SHIFT; - for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) { - pte_t pteval = *pte; - struct page *page; - int page_nid = -1; - int target_nid; - bool migrated = false; - int flags = 0; - - if (!pte_present(pteval)) - continue; - if (!pte_numa(pteval)) - continue; - if (addr >= vma->vm_end) { - vma = find_vma(mm, addr); - /* there's a pte present so there must be a vma */ - BUG_ON(!vma); - BUG_ON(addr < vma->vm_start); - } - if (pte_numa(pteval)) { - pteval = pte_mknonnuma(pteval); - set_pte_at(mm, addr, pte, pteval); - } - page = vm_normal_page(vma, addr, pteval); - if (unlikely(!page)) - continue; - - /* - * Avoid grouping on DSO/COW pages in specific and RO pages - * in general, RO pages shouldn't hurt as much anyway since - * they can be in shared cache state. - */ - if (!pte_write(pteval)) - flags |= TNF_NO_GROUP; - - last_cpupid = page_cpupid_last(page); - page_nid = page_to_nid(page); - target_nid = numa_migrate_prep(page, vma, addr, page_nid); - pte_unmap_unlock(pte, ptl); - if (target_nid != -1) { - migrated = migrate_misplaced_page(page, vma, target_nid); - if (migrated) { - page_nid = target_nid; - flags |= TNF_MIGRATED; - } - } else { - put_page(page); - } - - if (page_nid != -1) - task_numa_fault(last_cpupid, page_nid, 1, flags); - - pte = pte_offset_map_lock(mm, pmdp, addr, &ptl); - } - pte_unmap_unlock(orig_pte, ptl); - - return 0; -} -#else -static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long addr, pmd_t *pmdp) -{ - BUG(); - return 0; -} -#endif /* CONFIG_NUMA_BALANCING */ - /* * These routines also need to handle stuff like marking pages dirty * and/or accessed for architectures that don't do it in hardware (most @@ -3841,8 +3744,8 @@ retry: } } - if (pmd_numa(*pmd)) - return do_pmd_numa_page(mm, vma, address, pmd); + /* THP should already have been handled */ + BUG_ON(pmd_numa(*pmd)); /* * Use __pte_alloc instead of pte_alloc_map, because we can't diff --git a/mm/mprotect.c b/mm/mprotect.c index 9a74855..a0302ac 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -37,15 +37,12 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, pgprot_t newprot, - int dirty_accountable, int prot_numa, bool *ret_all_same_cpupid) + int dirty_accountable, int prot_numa) { struct mm_struct *mm = vma->vm_mm; pte_t *pte, oldpte; spinlock_t *ptl; unsigned long pages = 0; - bool all_same_cpupid = true; - int last_cpu = -1; - int last_pid = -1; pte = pte_offset_map_lock(mm, pmd, addr, &ptl); arch_enter_lazy_mmu_mode(); @@ -64,19 +61,6 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, page = vm_normal_page(vma, addr, oldpte); if (page) { - int cpupid = page_cpupid_last(page); - int this_cpu = cpupid_to_cpu(cpupid); - int this_pid = cpupid_to_pid(cpupid); - - if (last_cpu == -1) - last_cpu = this_cpu; - if (last_pid == -1) - last_pid = this_pid; - if (last_cpu != this_cpu || - last_pid != this_pid) { - all_same_cpupid = false; - } - if (!pte_numa(oldpte)) { ptent = pte_mknuma(ptent); updated = true; @@ -115,26 +99,9 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, arch_leave_lazy_mmu_mode(); pte_unmap_unlock(pte - 1, ptl); - *ret_all_same_cpupid = all_same_cpupid; return pages; } -#ifdef CONFIG_NUMA_BALANCING -static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr, - pmd_t *pmd) -{ - spin_lock(&mm->page_table_lock); - set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd)); - spin_unlock(&mm->page_table_lock); -} -#else -static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr, - pmd_t *pmd) -{ - BUG(); -} -#endif /* CONFIG_NUMA_BALANCING */ - static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *pud, unsigned long addr, unsigned long end, pgprot_t newprot, int dirty_accountable, int prot_numa) @@ -142,7 +109,6 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pmd_t *pmd; unsigned long next; unsigned long pages = 0; - bool all_same_cpupid; pmd = pmd_offset(pud, addr); do { @@ -168,17 +134,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, if (pmd_none_or_clear_bad(pmd)) continue; this_pages = change_pte_range(vma, pmd, addr, next, newprot, - dirty_accountable, prot_numa, &all_same_cpupid); + dirty_accountable, prot_numa); pages += this_pages; - - /* - * If we are changing protections for NUMA hinting faults then - * set pmd_numa if the examined pages were all on the same - * node. This allows a regular PMD to be handled as one fault - * and effectively batches the taking of the PTL - */ - if (prot_numa && this_pages && all_same_cpupid) - change_pmd_protnuma(vma->vm_mm, addr, pmd); } while (pmd++, addr = next, addr != end); return pages;