From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f172.google.com (mail-pd0-f172.google.com [209.85.192.172]) by kanga.kvack.org (Postfix) with ESMTP id AAB3F6B0038 for ; Fri, 7 Aug 2015 07:54:21 -0400 (EDT) Received: by pdrg1 with SMTP id g1so44809524pdr.2 for ; Fri, 07 Aug 2015 04:54:21 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTP id ve14si17240623pab.20.2015.08.07.04.54.20 for ; Fri, 07 Aug 2015 04:54:20 -0700 (PDT) From: "Kirill A. Shutemov" Subject: [PATCH] mm: take i_mmap_lock in unmap_mapping_range() for DAX Date: Fri, 7 Aug 2015 14:53:43 +0300 Message-Id: <1438948423-128882-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Matthew Wilcox Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" DAX is not so special: we need i_mmap_lock to protect mapping->i_mmap. __dax_pmd_fault() uses unmap_mapping_range() shoot out zero page from all mappings. We need to drop i_mmap_lock there to avoid lock deadlock. Re-aquiring the lock should be fine since we check i_size after the point. Not-yet-signed-off-by: Matthew Wilcox Signed-off-by: Kirill A. Shutemov --- fs/dax.c | 35 +++++++++++++++++++---------------- mm/memory.c | 11 ++--------- 2 files changed, 21 insertions(+), 25 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 9ef9b80cc132..ed54efedade6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -554,6 +554,25 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) goto fallback; + if (buffer_unwritten(&bh) || buffer_new(&bh)) { + int i; + for (i = 0; i < PTRS_PER_PMD; i++) + clear_page(kaddr + i * PAGE_SIZE); + count_vm_event(PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); + result |= VM_FAULT_MAJOR; + } + + /* + * If we allocated new storage, make sure no process has any + * zero pages covering this hole + */ + if (buffer_new(&bh)) { + i_mmap_unlock_write(mapping); + unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); + i_mmap_lock_write(mapping); + } + /* * If a truncate happened while we were allocating blocks, we may * leave blocks allocated to the file that are beyond EOF. We can't @@ -568,13 +587,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if ((pgoff | PG_PMD_COLOUR) >= size) goto fallback; - /* - * If we allocated new storage, make sure no process has any - * zero pages covering this hole - */ - if (buffer_new(&bh)) - unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); - if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { spinlock_t *ptl; pmd_t entry; @@ -605,15 +617,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) goto fallback; - if (buffer_unwritten(&bh) || buffer_new(&bh)) { - int i; - for (i = 0; i < PTRS_PER_PMD; i++) - clear_page(kaddr + i * PAGE_SIZE); - count_vm_event(PGMAJFAULT); - mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); - result |= VM_FAULT_MAJOR; - } - result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write); } diff --git a/mm/memory.c b/mm/memory.c index 5a3427bb3f32..670cdfa9f33e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2426,17 +2426,10 @@ void unmap_mapping_range(struct address_space *mapping, if (details.last_index < details.first_index) details.last_index = ULONG_MAX; - - /* - * DAX already holds i_mmap_lock to serialise file truncate vs - * page fault and page fault vs page fault. - */ - if (!IS_DAX(mapping->host)) - i_mmap_lock_write(mapping); + i_mmap_lock_write(mapping); if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) unmap_mapping_range_tree(&mapping->i_mmap, &details); - if (!IS_DAX(mapping->host)) - i_mmap_unlock_write(mapping); + i_mmap_unlock_write(mapping); } EXPORT_SYMBOL(unmap_mapping_range); -- 2.4.6 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org