From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751115AbVKUWFO (ORCPT ); Mon, 21 Nov 2005 17:05:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751118AbVKUWFO (ORCPT ); Mon, 21 Nov 2005 17:05:14 -0500 Received: from gold.veritas.com ([143.127.12.110]:59307 "EHLO gold.veritas.com") by vger.kernel.org with ESMTP id S1751115AbVKUWFM (ORCPT ); Mon, 21 Nov 2005 17:05:12 -0500 Date: Mon, 21 Nov 2005 20:35:01 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Andrew Morton cc: Paul Mackerras , Ben Herrenschmidt , linux-kernel@vger.kernel.org Subject: [PATCH 3/5] mm: powerpc ptlock comments In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 21 Nov 2005 20:34:51.0642 (UTC) FILETIME=[0608DDA0:01C5EEDB] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Update comments (only) on page_table_lock and mmap_sem in arch/powerpc. Removed the comment on page_table_lock from hash_huge_page: since it's no longer taking page_table_lock itself, it's irrelevant whether others are; but how it is safe (even against huge file truncation?) I can't say. Signed-off-by: Hugh Dickins --- arch/powerpc/mm/hugetlbpage.c | 4 +--- arch/powerpc/mm/mem.c | 2 +- arch/powerpc/mm/tlb_32.c | 6 ++++++ arch/powerpc/mm/tlb_64.c | 4 ++-- 4 files changed, 10 insertions(+), 6 deletions(-) --- 2.6.15-rc2/arch/powerpc/mm/hugetlbpage.c 2005-11-20 19:43:31.000000000 +0000 +++ linux/arch/powerpc/mm/hugetlbpage.c 2005-11-21 18:50:46.000000000 +0000 @@ -754,9 +754,7 @@ repeat: } /* - * No need to use ldarx/stdcx here because all who - * might be updating the pte will hold the - * page_table_lock + * No need to use ldarx/stdcx here */ *ptep = __pte(new_pte & ~_PAGE_BUSY); --- 2.6.15-rc2/arch/powerpc/mm/mem.c 2005-11-20 19:43:32.000000000 +0000 +++ linux/arch/powerpc/mm/mem.c 2005-11-21 18:50:46.000000000 +0000 @@ -495,7 +495,7 @@ EXPORT_SYMBOL(flush_icache_user_range); * We use it to preload an HPTE into the hash table corresponding to * the updated linux PTE. * - * This must always be called with the mm->page_table_lock held + * This must always be called with the pte lock held. */ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t pte) --- 2.6.15-rc2/arch/powerpc/mm/tlb_32.c 2005-11-20 19:43:32.000000000 +0000 +++ linux/arch/powerpc/mm/tlb_32.c 2005-11-21 18:50:46.000000000 +0000 @@ -149,6 +149,12 @@ void flush_tlb_mm(struct mm_struct *mm) return; } + /* + * It is safe to go down the mm's list of vmas when called + * from dup_mmap, holding mmap_sem. It would also be safe from + * unmap_region or exit_mmap, but not from vmtruncate on SMP - + * but it seems dup_mmap is the only SMP case which gets here. + */ for (mp = mm->mmap; mp != NULL; mp = mp->vm_next) flush_range(mp->vm_mm, mp->vm_start, mp->vm_end); FINISH_FLUSH; --- 2.6.15-rc2/arch/powerpc/mm/tlb_64.c 2005-11-20 19:43:32.000000000 +0000 +++ linux/arch/powerpc/mm/tlb_64.c 2005-11-21 18:50:46.000000000 +0000 @@ -95,7 +95,7 @@ static void pte_free_submit(struct pte_f void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf) { - /* This is safe as we are holding page_table_lock */ + /* This is safe since tlb_gather_mmu has disabled preemption */ cpumask_t local_cpumask = cpumask_of_cpu(smp_processor_id()); struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur); @@ -206,7 +206,7 @@ void __flush_tlb_pending(struct ppc64_tl void pte_free_finish(void) { - /* This is safe as we are holding page_table_lock */ + /* This is safe since tlb_gather_mmu has disabled preemption */ struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur); if (*batchp == NULL)