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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 566EFC636D7 for ; Sat, 18 Feb 2023 08:02:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229591AbjBRICu (ORCPT ); Sat, 18 Feb 2023 03:02:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229614AbjBRICt (ORCPT ); Sat, 18 Feb 2023 03:02:49 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E115A4DE3E for ; Sat, 18 Feb 2023 00:02:47 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 956AEB82E8A for ; Sat, 18 Feb 2023 08:02:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E53CCC4339B; Sat, 18 Feb 2023 08:02:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1676707365; bh=J03DmW9CUJ7CobuSew49uvg1+Sv6derYpCSExpSoJbo=; h=Subject:To:Cc:From:Date:From; b=w111Rhp0EwI7O7Nim0Hri46e+RLRpvHINhoTsI6PJOx6hCgeeQf4yy6L5zoFcvosU 3X10JcI07eOpL/uyIAI6LML0Af9ZHAhDpisbjRWMFwUIAR4WK/2izSsgnVDh+sGEKz 6lLV0vQxrNDFiyQpqcQg3TwrvSnkGUBPAzvBEwdQ= Subject: FAILED: patch "[PATCH] mm/filemap: fix page end in filemap_get_read_batch" failed to apply to 5.15-stable tree To: qian@ddn.com, akpm@linux-foundation.org, stable@vger.kernel.org, willy@infradead.org Cc: From: Date: Sat, 18 Feb 2023 09:02:42 +0100 Message-ID: <167670736248208@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Possible dependencies: 5956592ce337 ("mm/filemap: fix page end in filemap_get_read_batch") 25d6a23e8d28 ("filemap: Convert filemap_get_read_batch() to use a folio_batch") d996fc7f615f ("filemap: Convert filemap_read() to use a folio") 65bca53b5f63 ("filemap: Convert filemap_get_pages to use folios") a5d4ad098528 ("filemap: Convert filemap_create_page to folio") 9d427b4eb456 ("filemap: Convert filemap_read_page to take a folio") bdb729329769 ("filemap: Convert filemap_get_read_batch to use folios") 512b7931ad05 ("Merge branch 'akpm' (patches from Andrew)") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 5956592ce337330cdff0399a6f8b6a5aea397a8e Mon Sep 17 00:00:00 2001 From: Qian Yingjin Date: Wed, 8 Feb 2023 10:24:00 +0800 Subject: [PATCH] mm/filemap: fix page end in filemap_get_read_batch I was running traces of the read code against an RAID storage system to understand why read requests were being misaligned against the underlying RAID strips. I found that the page end offset calculation in filemap_get_read_batch() was off by one. When a read is submitted with end offset 1048575, then it calculates the end page for read of 256 when it should be 255. "last_index" is the index of the page beyond the end of the read and it should be skipped when get a batch of pages for read in @filemap_get_read_batch(). The below simple patch fixes the problem. This code was introduced in kernel 5.12. Link: https://lkml.kernel.org/r/20230208022400.28962-1-coolqyj@163.com Fixes: cbd59c48ae2b ("mm/filemap: use head pages in generic_file_buffered_read") Signed-off-by: Qian Yingjin Reviewed-by: Matthew Wilcox (Oracle) Cc: Signed-off-by: Andrew Morton diff --git a/mm/filemap.c b/mm/filemap.c index c4d4ace9cc70..0e20a8d6dd93 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2588,18 +2588,19 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, struct folio *folio; int err = 0; + /* "last_index" is the index of the page beyond the end of the read */ last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE); retry: if (fatal_signal_pending(current)) return -EINTR; - filemap_get_read_batch(mapping, index, last_index, fbatch); + filemap_get_read_batch(mapping, index, last_index - 1, fbatch); if (!folio_batch_count(fbatch)) { if (iocb->ki_flags & IOCB_NOIO) return -EAGAIN; page_cache_sync_readahead(mapping, ra, filp, index, last_index - index); - filemap_get_read_batch(mapping, index, last_index, fbatch); + filemap_get_read_batch(mapping, index, last_index - 1, fbatch); } if (!folio_batch_count(fbatch)) { if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))