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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A38DC4332F for ; Wed, 2 Nov 2022 14:41:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CB0B48E0002; Wed, 2 Nov 2022 10:41:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C60C58E0001; Wed, 2 Nov 2022 10:41:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B4F418E0002; Wed, 2 Nov 2022 10:41:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 9F2008E0001 for ; Wed, 2 Nov 2022 10:41:43 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 69B5A141228 for ; Wed, 2 Nov 2022 14:41:43 +0000 (UTC) X-FDA: 80088766086.14.34D61A7 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf18.hostedemail.com (Postfix) with ESMTP id DE0081C0002 for ; Wed, 2 Nov 2022 14:41:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=pEKpUx0E1zKlXRsfIwLINmLCvgphBiCWjAsz0rcY7cs=; b=OPcZ2vRkmNrbxjUUD6JzSICZ3D d+BYBQ6dU+M0pse3fKeTNKdBR1XLfW2+8Kb/jhzsUgvnFOTkJ8GjYt1cELZSe/yrb8m82wubitFr4 /0zNWQtwfz3umLPyBiDU9MybusGyIG1560ayPZ5IbcoaLF+UhWqEgYm1DChxmQVfZFkNXGDZUeRZt Sh5UPgbETvRM2EgZIlWSj56mm/UffuwiSepxIHXVW01GyabbYfeQfwX2jRVlHhdLi851/V0JbrXB9 8hJAFVGaiY+xOtvIK7gz/eJJ42B/Qk7o8kaX/Qry8ZGCXMYB7dFEnJKEz4eslua7TzJXZEnIwPwtW +WEvPOFw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oqEvy-005aSH-Pj; Wed, 02 Nov 2022 14:41:38 +0000 Date: Wed, 2 Nov 2022 14:41:38 +0000 From: Matthew Wilcox To: Rui Wang Cc: linux-mm@kvack.org, Guoqi , Huacai Chen , Rui Wang Subject: Re: [RFC PATCH] mm/shmem: Fix undo range for failed fallocate Message-ID: References: <20221101032248.819360-1-kernel@hev.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221101032248.819360-1-kernel@hev.cc> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667400102; a=rsa-sha256; cv=none; b=DAiD8tfmg8RT8MqyfPRiOcZH4NuinRuiRIqzxxBqmktZoikzJlyRurD+/dnuyne+/XklIS 9OQ9M0DZkYfb/IoSBvBcVbblvhgr+uXxq20YK7ot+YzOmFa8uK3GeBeyauDopoHIAvfXKQ a9fdWIWim3aLL6q6Qy9v7kEyJ9zvmmQ= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=OPcZ2vRk; dmarc=none; spf=none (imf18.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667400102; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=pEKpUx0E1zKlXRsfIwLINmLCvgphBiCWjAsz0rcY7cs=; b=Iv3ERCU553eEgafI/CMB/PHLRu1wrEWTwoz8mdknOoWf1Oy/Fh6hPxWz9CUvSzl0QN8SyN AIXa4gxeeRufZ3sn7FgMaSbwcVAfN5im+HuUcnHoMLDwPVlp5HiyqXCOtTVNEJyUFl98eX WObKZA7uC/Sh1544ls/qVuf4eLutgAU= X-Stat-Signature: ntk4iogeokysstpryg3jou5pk5mw58s4 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: DE0081C0002 X-Rspam-User: Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=OPcZ2vRk; dmarc=none; spf=none (imf18.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1667400100-691942 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: On Tue, Nov 01, 2022 at 11:22:48AM +0800, Rui Wang wrote: > This patch fixes data loss caused by the fallocate system > call interrupted by a signal. > > Bug: https://lore.kernel.org/linux-mm/33b85d82.7764.1842e9ab207.Coremail.chenguoqic@163.com/ > Fixes: b9a8a4195c7d ("truncate,shmem: Handle truncates that split large folios") How does that commit introduce this bug? > Reported-by: Guoqi Chen > Cc: Huacai Chen > Signed-off-by: Rui Wang > --- > mm/shmem.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index bc9b84602eec..8c8dce34eafc 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -948,11 +948,13 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, > folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT); > if (folio) { > same_folio = lend < folio_pos(folio) + folio_size(folio); > - folio_mark_dirty(folio); > - if (!truncate_inode_partial_folio(folio, lstart, lend)) { > - start = folio->index + folio_nr_pages(folio); > - if (same_folio) > - end = folio->index; > + if (!unfalloc || !folio_test_uptodate(folio)) { > + folio_mark_dirty(folio); > + if (!truncate_inode_partial_folio(folio, lstart, lend)) { > + start = folio->index + folio_nr_pages(folio); > + if (same_folio) > + end = folio->index; > + } ... so what you're saying is that if we allocate a page, but zeroing it is interrupted by a signal, we cannot now remove that page from the cache? That seems wrong. Surely the right solution is to remove this page from the cache if we're interrupted by a signal.