From patchwork Sat Mar 10 06:55:15 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 10273271 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 3E242601A0 for ; Sat, 10 Mar 2018 07:06:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2D478287E6 for ; Sat, 10 Mar 2018 07:06:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 21C3C29F01; Sat, 10 Mar 2018 07:06:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B5555287E6 for ; Sat, 10 Mar 2018 07:06:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932990AbeCJHEY (ORCPT ); Sat, 10 Mar 2018 02:04:24 -0500 Received: from mga02.intel.com ([134.134.136.20]:19755 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932918AbeCJHEW (ORCPT ); Sat, 10 Mar 2018 02:04:22 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Mar 2018 23:04:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,449,1515484800"; d="scan'208";a="36139402" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by fmsmga004.fm.intel.com with ESMTP; 09 Mar 2018 23:04:20 -0800 Subject: [PATCH v5 05/11] fs, dax: use page->mapping to warn if truncate collides with a busy page From: Dan Williams To: linux-nvdimm@lists.01.org Cc: Jeff Moyer , Matthew Wilcox , Ross Zwisler , Jan Kara , Christoph Hellwig , david@fromorbit.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, jack@suse.cz, ross.zwisler@linux.intel.com, hch@lst.de, linux-kernel@vger.kernel.org Date: Fri, 09 Mar 2018 22:55:15 -0800 Message-ID: <152066491575.40260.4558985474642451800.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <152066488891.40260.14605734226832760468.stgit@dwillia2-desk3.amr.corp.intel.com> References: <152066488891.40260.14605734226832760468.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-2-gc94f MIME-Version: 1.0 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Catch cases where extent unmap operations encounter pages that are pinned / busy. Typically this is pinned pages that are under active dma. This warning is a canary for potential data corruption as truncated blocks could be allocated to a new file while the device is still performing i/o. Here is an example of a collision that this implementation catches: WARNING: CPU: 2 PID: 1286 at fs/dax.c:343 dax_disassociate_entry+0x55/0x80 [..] Call Trace: __dax_invalidate_mapping_entry+0x6c/0xf0 dax_delete_mapping_entry+0xf/0x20 truncate_exceptional_pvec_entries.part.12+0x1af/0x200 truncate_inode_pages_range+0x268/0x970 ? tlb_gather_mmu+0x10/0x20 ? up_write+0x1c/0x40 ? unmap_mapping_range+0x73/0x140 xfs_free_file_space+0x1b6/0x5b0 [xfs] ? xfs_file_fallocate+0x7f/0x320 [xfs] ? down_write_nested+0x40/0x70 ? xfs_ilock+0x21d/0x2f0 [xfs] xfs_file_fallocate+0x162/0x320 [xfs] ? rcu_read_lock_sched_held+0x3f/0x70 ? rcu_sync_lockdep_assert+0x2a/0x50 ? __sb_start_write+0xd0/0x1b0 ? vfs_fallocate+0x20c/0x270 vfs_fallocate+0x154/0x270 SyS_fallocate+0x43/0x80 entry_SYSCALL_64_fastpath+0x1f/0x96 Cc: Jeff Moyer Cc: Matthew Wilcox Cc: Ross Zwisler Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig Signed-off-by: Dan Williams --- fs/dax.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/dax.c b/fs/dax.c index ba02772fccbc..fecf463a1468 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -325,6 +325,56 @@ static void put_unlocked_mapping_entry(struct address_space *mapping, dax_wake_mapping_entry_waiter(mapping, index, entry, false); } +static unsigned long dax_entry_size(void *entry) +{ + if (dax_is_zero_entry(entry)) + return 0; + else if (dax_is_empty_entry(entry)) + return 0; + else if (dax_is_pmd_entry(entry)) + return HPAGE_SIZE; + else + return PAGE_SIZE; +} + +#define for_each_entry_pfn(entry, pfn, end_pfn) \ + for (pfn = dax_radix_pfn(entry), \ + end_pfn = pfn + dax_entry_size(entry) / PAGE_SIZE; \ + pfn < end_pfn; \ + pfn++) + +static void dax_associate_entry(void *entry, struct address_space *mapping) +{ + unsigned long pfn, end_pfn; + + if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) + return; + + for_each_entry_pfn(entry, pfn, end_pfn) { + struct page *page = pfn_to_page(pfn); + + WARN_ON_ONCE(page->mapping); + page->mapping = mapping; + } +} + +static void dax_disassociate_entry(void *entry, struct address_space *mapping, + bool trunc) +{ + unsigned long pfn, end_pfn; + + if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) + return; + + for_each_entry_pfn(entry, pfn, end_pfn) { + struct page *page = pfn_to_page(pfn); + + WARN_ON_ONCE(trunc && page_ref_count(page) > 1); + WARN_ON_ONCE(page->mapping && page->mapping != mapping); + page->mapping = NULL; + } +} + /* * Find radix tree entry at given index. If it points to an exceptional entry, * return it with the radix tree entry locked. If the radix tree doesn't @@ -431,6 +481,7 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index, } if (pmd_downgrade) { + dax_disassociate_entry(entry, mapping, false); radix_tree_delete(&mapping->page_tree, index); mapping->nrexceptional--; dax_wake_mapping_entry_waiter(mapping, index, entry, @@ -480,6 +531,7 @@ static int __dax_invalidate_mapping_entry(struct address_space *mapping, (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) || radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))) goto out; + dax_disassociate_entry(entry, mapping, trunc); radix_tree_delete(page_tree, index); mapping->nrexceptional--; ret = 1; @@ -574,6 +626,10 @@ static void *dax_insert_mapping_entry(struct address_space *mapping, spin_lock_irq(&mapping->tree_lock); new_entry = dax_radix_locked_entry(pfn, flags); + if (dax_entry_size(entry) != dax_entry_size(new_entry)) { + dax_disassociate_entry(entry, mapping, false); + dax_associate_entry(new_entry, mapping); + } if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { /*