From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C15FC433F5 for ; Mon, 28 Feb 2022 06:36:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233299AbiB1GhR (ORCPT ); Mon, 28 Feb 2022 01:37:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233271AbiB1GhK (ORCPT ); Mon, 28 Feb 2022 01:37:10 -0500 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A75666CAC for ; Sun, 27 Feb 2022 22:36:31 -0800 (PST) Received: by mail-pj1-x1031.google.com with SMTP id cp23-20020a17090afb9700b001bbfe0fbe94so10454864pjb.3 for ; Sun, 27 Feb 2022 22:36:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=FG/K6837zQPVwcpe+tAz7OlRAj17PMacY8wX1oMHrEs=; b=g/GhQOqHJ24ceuqRTB3sVPp8shVFkKLFyVMAs47Cr+pWlvR8I5AOpmCZe03LtQGTJG jbbT72JbvxN88Ub71vLWOxTzQk6Z6AfcN6QH0oJSkFMYc9zDVQw7QHzxlRLq5uJifMWS H0MlXkgEmiyiDZN6k9zMMD0VP3xHLJO6OaUfSqF2FX0mUXjZS5BtM4D1aFOpTkXJP6SH LgfueRhw4s1GCH6CUZUuQ13cVpIVnn0gkXERZhoJT/MDNk/byxoFpJkoavFzB4uJVL1+ Suty827tYe0lrS8vssDo6OedkAaH1cOTqz7Jt6o+fTaSsy6Ov/WY8nmt0Ga3LxATDXEK N/PA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=FG/K6837zQPVwcpe+tAz7OlRAj17PMacY8wX1oMHrEs=; b=tn+R6bjrpYg+26sogBXA5FPBL88jWTr/cwenGru2/MdsU+nO+h/K6j0EknYCeAEOCP veyCleNw6K9MlpX9PIAkYUfFDXyqvUyOFc6xvXnfBQ18XmrRE+X2nor7ezFqRtZGqSqn TdjF6ypiV5shDWDZIJPdTlkUR9d1u/Ft2gJTYnGoN4YNh3r6PTZsuZIF78PH/83IN8bC Bpt/XmgAR/pjGLQtR7f5OOHRragPOFvBn+PQiM5spD+NxEo9BDdisUPjFSQIB8yTagUz j2uL4Mc6xoQ9ztCtkFdpSt5RNxKnt+77kHE20hf+WaT1cofUzO4s/iinYg8qbk+c91kD U7/Q== X-Gm-Message-State: AOAM532tRLP+aJ0Hxxxyn0FBq6tYgGSBI/+loC34OQ2FmFPVKfFuAZHF GknMYvTS1O2VA4x7LdFKvQDBPA== X-Google-Smtp-Source: ABdhPJxBp5q5CAro36s0XsQJyPMFX8KTntJhp3Efe/EJOJMtZj9iqhZtKfUiHCZdAD/xYH38wRZ/yw== X-Received: by 2002:a17:90b:3c01:b0:1bc:b160:7811 with SMTP id pb1-20020a17090b3c0100b001bcb1607811mr15115550pjb.164.1646030190625; Sun, 27 Feb 2022 22:36:30 -0800 (PST) Received: from FVFYT0MHHV2J.tiktokcdn.com ([139.177.225.227]) by smtp.gmail.com with ESMTPSA id q13-20020aa7960d000000b004f13804c100sm11126472pfg.165.2022.02.27.22.36.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Feb 2022 22:36:30 -0800 (PST) From: Muchun Song To: dan.j.williams@intel.com, willy@infradead.org, jack@suse.cz, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, apopple@nvidia.com, shy828301@gmail.com, rcampbell@nvidia.com, hughd@google.com, xiyuyang19@fudan.edu.cn, kirill.shutemov@linux.intel.com, zwisler@kernel.org, hch@infradead.org Cc: linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, smuchun@gmail.com, Muchun Song Subject: [PATCH v3 5/6] dax: fix missing writeprotect the pte entry Date: Mon, 28 Feb 2022 14:35:35 +0800 Message-Id: <20220228063536.24911-6-songmuchun@bytedance.com> X-Mailer: git-send-email 2.32.0 (Apple Git-132) In-Reply-To: <20220228063536.24911-1-songmuchun@bytedance.com> References: <20220228063536.24911-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently dax_mapping_entry_mkclean() fails to clean and write protect the pte entry within a DAX PMD entry during an *sync operation. This can result in data loss in the following sequence: 1) process A mmap write to DAX PMD, dirtying PMD radix tree entry and making the pmd entry dirty and writeable. 2) process B mmap with the @offset (e.g. 4K) and @length (e.g. 4K) write to the same file, dirtying PMD radix tree entry (already done in 1)) and making the pte entry dirty and writeable. 3) fsync, flushing out PMD data and cleaning the radix tree entry. We currently fail to mark the pte entry as clean and write protected since the vma of process B is not covered in dax_entry_mkclean(). 4) process B writes to the pte. These don't cause any page faults since the pte entry is dirty and writeable. The radix tree entry remains clean. 5) fsync, which fails to flush the dirty PMD data because the radix tree entry was clean. 6) crash - dirty data that should have been fsync'd as part of 5) could still have been in the processor cache, and is lost. Just to use pfn_mkclean_range() to clean the pfns to fix this issue. Fixes: 4b4bb46d00b3 ("dax: clear dirty entry tags on cache flush") Signed-off-by: Muchun Song --- fs/dax.c | 83 ++++++---------------------------------------------------------- 1 file changed, 7 insertions(+), 76 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index a372304c9695..7fd4a16769f9 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #define CREATE_TRACE_POINTS @@ -789,87 +790,17 @@ static void *dax_insert_entry(struct xa_state *xas, return entry; } -static inline -unsigned long pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma) -{ - unsigned long address; - - address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); - VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); - return address; -} - /* Walk all mappings of a given index of a file and writeprotect them */ -static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index, - unsigned long pfn) +static void dax_entry_mkclean(struct address_space *mapping, unsigned long pfn, + unsigned long npfn, pgoff_t start) { struct vm_area_struct *vma; - pte_t pte, *ptep = NULL; - pmd_t *pmdp = NULL; - spinlock_t *ptl; + pgoff_t end = start + npfn - 1; i_mmap_lock_read(mapping); - vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) { - struct mmu_notifier_range range; - unsigned long address; - + vma_interval_tree_foreach(vma, &mapping->i_mmap, start, end) { + pfn_mkclean_range(pfn, npfn, start, vma); cond_resched(); - - if (!(vma->vm_flags & VM_SHARED)) - continue; - - address = pgoff_address(index, vma); - - /* - * follow_invalidate_pte() will use the range to call - * mmu_notifier_invalidate_range_start() on our behalf before - * taking any lock. - */ - if (follow_invalidate_pte(vma->vm_mm, address, &range, &ptep, - &pmdp, &ptl)) - continue; - - /* - * No need to call mmu_notifier_invalidate_range() as we are - * downgrading page table protection not changing it to point - * to a new page. - * - * See Documentation/vm/mmu_notifier.rst - */ - if (pmdp) { -#ifdef CONFIG_FS_DAX_PMD - pmd_t pmd; - - if (pfn != pmd_pfn(*pmdp)) - goto unlock_pmd; - if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp)) - goto unlock_pmd; - - flush_cache_range(vma, address, - address + HPAGE_PMD_SIZE); - pmd = pmdp_invalidate(vma, address, pmdp); - pmd = pmd_wrprotect(pmd); - pmd = pmd_mkclean(pmd); - set_pmd_at(vma->vm_mm, address, pmdp, pmd); -unlock_pmd: -#endif - spin_unlock(ptl); - } else { - if (pfn != pte_pfn(*ptep)) - goto unlock_pte; - if (!pte_dirty(*ptep) && !pte_write(*ptep)) - goto unlock_pte; - - flush_cache_page(vma, address, pfn); - pte = ptep_clear_flush(vma, address, ptep); - pte = pte_wrprotect(pte); - pte = pte_mkclean(pte); - set_pte_at(vma->vm_mm, address, ptep, pte); -unlock_pte: - pte_unmap_unlock(ptep, ptl); - } - - mmu_notifier_invalidate_range_end(&range); } i_mmap_unlock_read(mapping); } @@ -937,7 +868,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, count = 1UL << dax_entry_order(entry); index = xas->xa_index & ~(count - 1); - dax_entry_mkclean(mapping, index, pfn); + dax_entry_mkclean(mapping, pfn, count, index); dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_SIZE); /* * After we have flushed the cache, we can clear the dirty tag. There -- 2.11.0