From patchwork Fri Aug 12 18:37:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirill A . Shutemov" X-Patchwork-Id: 9277815 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 655C960780 for ; Fri, 12 Aug 2016 18:49:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5AEE428AD0 for ; Fri, 12 Aug 2016 18:49:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4FDD428AD5; Fri, 12 Aug 2016 18:49:00 +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 0035E28AD0 for ; Fri, 12 Aug 2016 18:48:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752447AbcHLSiq (ORCPT ); Fri, 12 Aug 2016 14:38:46 -0400 Received: from mga09.intel.com ([134.134.136.24]:35159 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752395AbcHLSip (ORCPT ); Fri, 12 Aug 2016 14:38:45 -0400 Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP; 12 Aug 2016 11:38:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,512,1464678000"; d="scan'208";a="154940170" Received: from black.fi.intel.com ([10.237.72.93]) by fmsmga004.fm.intel.com with ESMTP; 12 Aug 2016 11:38:39 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id C89BF35A; Fri, 12 Aug 2016 21:38:33 +0300 (EEST) From: "Kirill A. Shutemov" To: "Theodore Ts'o" , Andreas Dilger , Jan Kara , Andrew Morton Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv2 11/41] thp: try to free page's buffers before attempt split Date: Fri, 12 Aug 2016 21:37:54 +0300 Message-Id: <1471027104-115213-12-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1471027104-115213-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1471027104-115213-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP We want page to be isolated from the rest of the system before spliting it. We rely on page count to be 2 for file pages to make sure nobody uses the page: one pin to caller, one to radix-tree. Filesystems with backing storage can have page count increased if it has buffers. Let's try to free them, before attempt split. And remove one guarding VM_BUG_ON_PAGE(). Signed-off-by: Kirill A. Shutemov --- include/linux/buffer_head.h | 1 + mm/huge_memory.c | 19 ++++++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index ebbacd14d450..006a8a42acfb 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -395,6 +395,7 @@ extern int __set_page_dirty_buffers(struct page *page); #else /* CONFIG_BLOCK */ static inline void buffer_init(void) {} +static inline int page_has_buffers(struct page *page) { return 0; } static inline int try_to_free_buffers(struct page *page) { return 1; } static inline int inode_has_buffers(struct inode *inode) { return 0; } static inline void invalidate_inode_buffers(struct inode *inode) {} diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 73e80d49c32e..a8fcfa3010c8 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include @@ -2007,7 +2008,6 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) VM_BUG_ON_PAGE(is_huge_zero_page(page), page); VM_BUG_ON_PAGE(!PageLocked(page), page); - VM_BUG_ON_PAGE(!PageSwapBacked(page), page); VM_BUG_ON_PAGE(!PageCompound(page), page); if (PageAnon(head)) { @@ -2036,6 +2036,23 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) goto out; } + /* Try to free buffers before attempt split */ + if (!PageSwapBacked(head) && PagePrivate(page)) { + /* + * We cannot trigger writeback from here due possible + * recursion if triggered from vmscan, only wait. + * + * Caller can trigger writeback it on its own, if safe. + */ + wait_on_page_writeback(head); + + if (page_has_buffers(head) && + !try_to_free_buffers(head)) { + ret = -EBUSY; + goto out; + } + } + /* Addidional pin from radix tree */ extra_pins = 1; anon_vma = NULL;