From patchwork Wed May 5 01:32:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12238757 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 143CCC433B4 for ; Wed, 5 May 2021 01:33:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9BF99613C5 for ; Wed, 5 May 2021 01:32:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9BF99613C5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 320B48D000C; Tue, 4 May 2021 21:32:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2F7248D0003; Tue, 4 May 2021 21:32:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1E7428D000C; Tue, 4 May 2021 21:32:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0049.hostedemail.com [216.40.44.49]) by kanga.kvack.org (Postfix) with ESMTP id 02DD08D0003 for ; Tue, 4 May 2021 21:32:58 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id B4B41181AF5C3 for ; Wed, 5 May 2021 01:32:58 +0000 (UTC) X-FDA: 78105453636.05.FBF2DA9 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP id 4125BE000119 for ; Wed, 5 May 2021 01:32:54 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 6E2E1613CB; Wed, 5 May 2021 01:32:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1620178377; bh=YQKncc8zJ+FulTs1lYRorDaeRAH2+rQNmJWjJHTiYDY=; h=Date:From:To:Subject:In-Reply-To:From; b=LQualH9ZPLEwuHbaa/nqg7mNhHkWtlMnhacfGNXDb0nFHMxRuR1c6MgYoo/CK36/c rqztIo+beyL3J094P5AUdB/wdBaNIBxWxnkAfEIaqkrf4PNoHCvseWtSkQetdQQQgO hC9EkyNE7vNrV6nPBbnevmoVkxErD5aFYk3ClS2w= Date: Tue, 04 May 2021 18:32:57 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hughd@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 005/143] mm: remove nrexceptional from inode: remove BUG_ON Message-ID: <20210505013257.HZsCu951B%akpm@linux-foundation.org> In-Reply-To: <20210504183219.a3cc46aee4013d77402276c5@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LQualH9Z; spf=pass (imf05.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4125BE000119 X-Stat-Signature: earq9w31hpfpnr41cqtidr8a3gajs9ju Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620178374-834166 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Hugh Dickins Subject: mm: remove nrexceptional from inode: remove BUG_ON clear_inode()'s BUG_ON(!mapping_empty(&inode->i_data)) is unsafe: we know of two ways in which nodes can and do (on rare occasions) get left behind. Until those are fixed, do not BUG_ON() nor even WARN_ON(). Yes, this will then leak those nodes (or the next user of the struct inode may use them); but this has been happening for years, and the new BUG_ON(!mapping_empty) was only guilty of revealing that. A proper fix will follow, but no hurry. Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104292229380.16080@eggly.anvils Signed-off-by: Hugh Dickins Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- fs/inode.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/fs/inode.c~mm-remove-nrexceptional-from-inode-remove-bug_on +++ a/fs/inode.c @@ -529,7 +529,14 @@ void clear_inode(struct inode *inode) */ xa_lock_irq(&inode->i_data.i_pages); BUG_ON(inode->i_data.nrpages); - BUG_ON(!mapping_empty(&inode->i_data)); + /* + * Almost always, mapping_empty(&inode->i_data) here; but there are + * two known and long-standing ways in which nodes may get left behind + * (when deep radix-tree node allocation failed partway; or when THP + * collapse_file() failed). Until those two known cases are cleaned up, + * or a cleanup function is called here, do not BUG_ON(!mapping_empty), + * nor even WARN_ON(!mapping_empty). + */ xa_unlock_irq(&inode->i_data.i_pages); BUG_ON(!list_empty(&inode->i_data.private_list)); BUG_ON(!(inode->i_state & I_FREEING));