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 X-Spam-Level: X-Spam-Status: No, score=-15.7 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=ham 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 49BCDC43600 for ; Fri, 23 Apr 2021 21:29:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E8BC8613AB for ; Fri, 23 Apr 2021 21:29:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E8BC8613AB 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 8CD536B0071; Fri, 23 Apr 2021 17:29:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A5096B0072; Fri, 23 Apr 2021 17:29:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6F8FA6B0073; Fri, 23 Apr 2021 17:29:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0199.hostedemail.com [216.40.44.199]) by kanga.kvack.org (Postfix) with ESMTP id 53D016B0071 for ; Fri, 23 Apr 2021 17:29:02 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 15CE863E6 for ; Fri, 23 Apr 2021 21:29:02 +0000 (UTC) X-FDA: 78064922124.10.89AABBB Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf18.hostedemail.com (Postfix) with ESMTP id D14B42000250 for ; Fri, 23 Apr 2021 21:29:03 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id AC01661494; Fri, 23 Apr 2021 21:29:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619213341; bh=R3+psPEHjS+f/1eA5d+m6Sr3gUYoybDcFxwQkDyVIwQ=; h=Date:From:To:Subject:In-Reply-To:From; b=U+Jb8DJIaE0DTkt+JBqHAEHzTo7DOV9Z5I7zx4DUysVJ56AHxl1WjzXfqm7jbPLYj rCZR8gIbkqbdYSv7n40tXfybnsSX7aYLCbOZkj83cQFrCzPCO0ohUorUQhmMabxJFH 1ZLXFhJU2nlNzA38j/zCCDUoIv9MIjL1tgg+Zk5g= Date: Fri, 23 Apr 2021 14:29:00 -0700 From: Andrew Morton To: akpm@linux-foundation.org, dchinner@redhat.com, hannes@cmpxchg.org, hch@lst.de, hughd@google.com, jack@suse.cz, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, william.kucharski@oracle.com, willy@infradead.org, yang.shi@linux.alibaba.com Subject: [patch 4/5] mm/filemap: fix mapping_seek_hole_data on THP & 32-bit Message-ID: <20210423212900.bdXHf5h31%akpm@linux-foundation.org> In-Reply-To: <20210423142805.fd6d718ec3296452108b3ee0@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D14B42000250 X-Stat-Signature: q1dee7zu9iitdpwm63zogqbuptcugtij Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf18; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619213343-387244 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/filemap: fix mapping_seek_hole_data on THP & 32-bit No problem on 64-bit without huge pages, but xfstests generic/285 and other SEEK_HOLE/SEEK_DATA tests have regressed on huge tmpfs, and on 32-bit architectures, with the new mapping_seek_hole_data(). Several different bugs turned out to need fixing. u64 cast to stop losing bits when converting unsigned long to loff_t (and let's use shifts throughout, rather than mixed with * and /). Use round_up() when advancing pos, to stop assuming that pos was already THP-aligned when advancing it by THP-size. (This use of round_up() assumes that any THP has THP-aligned index: true at present and true going forward, but could be recoded to avoid the assumption.) Use xas_set() when iterating away from a THP, so that xa_index stays in synch with start, instead of drifting away to return bogus offset. Check start against end to avoid wrapping 32-bit xa_index to 0 (and to handle these additional cases, seek_data or not, it's easier to break the loop than goto: so rearrange exit from the function). [hughd@google.com: remove unneeded u64 casts, per Matthew] Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104221347240.1170@eggly.anvils Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104211737410.3299@eggly.anvils Fixes: 41139aa4c3a3 ("mm/filemap: add mapping_seek_hole_data") Signed-off-by: Hugh Dickins Cc: Christoph Hellwig Cc: Dave Chinner Cc: Jan Kara Cc: Johannes Weiner Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox Cc: William Kucharski Cc: Yang Shi Signed-off-by: Andrew Morton --- mm/filemap.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) --- a/mm/filemap.c~mm-filemap-fix-mapping_seek_hole_data-on-thp-32-bit +++ a/mm/filemap.c @@ -2678,7 +2678,7 @@ loff_t mapping_seek_hole_data(struct add loff_t end, int whence) { XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT); - pgoff_t max = (end - 1) / PAGE_SIZE; + pgoff_t max = (end - 1) >> PAGE_SHIFT; bool seek_data = (whence == SEEK_DATA); struct page *page; @@ -2687,7 +2687,8 @@ loff_t mapping_seek_hole_data(struct add rcu_read_lock(); while ((page = find_get_entry(&xas, max, XA_PRESENT))) { - loff_t pos = xas.xa_index * PAGE_SIZE; + loff_t pos = (u64)xas.xa_index << PAGE_SHIFT; + unsigned int seek_size; if (start < pos) { if (!seek_data) @@ -2695,25 +2696,25 @@ loff_t mapping_seek_hole_data(struct add start = pos; } - pos += seek_page_size(&xas, page); + seek_size = seek_page_size(&xas, page); + pos = round_up(pos + 1, seek_size); start = page_seek_hole_data(&xas, mapping, page, start, pos, seek_data); if (start < pos) goto unlock; + if (start >= end) + break; + if (seek_size > PAGE_SIZE) + xas_set(&xas, pos >> PAGE_SHIFT); if (!xa_is_value(page)) put_page(page); } - rcu_read_unlock(); - if (seek_data) - return -ENXIO; - goto out; - + start = -ENXIO; unlock: rcu_read_unlock(); - if (!xa_is_value(page)) + if (page && !xa_is_value(page)) put_page(page); -out: if (start > end) return end; return start; _