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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 450D1C4727D for ; Tue, 22 Sep 2020 17:25:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF820206DC for ; Tue, 22 Sep 2020 17:25:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KaGUDsgh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726631AbgIVRZu (ORCPT ); Tue, 22 Sep 2020 13:25:50 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:58680 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726608AbgIVRZu (ORCPT ); Tue, 22 Sep 2020 13:25:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600795549; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KZmFKoK2MR7ChNH+SzztUzepcIAB3ilvtz5u7xppUU8=; b=KaGUDsghMH06JVkDh9tBIO7FrkwGAkaXtk+MyCbqRfmz1Y3Vy477b/ItzZR4GEVU/ZEetM a3hXnITqhmUmX0PWopJAaVuwvc7a8tE523PnTZQpWdeD19aamHhi2uJL64fPp3Lq0KkUOL dLkGlWj4IR5FZ7W1YmU5qqMwmhl+nVs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-463-mvCMT2fhNdqivAS76rFhIg-1; Tue, 22 Sep 2020 13:25:46 -0400 X-MC-Unique: mvCMT2fhNdqivAS76rFhIg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EBC1D80EF8B; Tue, 22 Sep 2020 17:25:44 +0000 (UTC) Received: from ovpn-66-35.rdu2.redhat.com (unknown [10.10.67.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id 606C310013D7; Tue, 22 Sep 2020 17:25:43 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 5/9] iomap: Support arbitrarily many blocks per page From: Qian Cai To: Matthew Wilcox Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Darrick J . Wong" , Christoph Hellwig , linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, Dave Kleikamp , jfs-discussion@lists.sourceforge.net, Dave Chinner , Stephen Rothwell , linux-next@vger.kernel.org Date: Tue, 22 Sep 2020 13:25:42 -0400 In-Reply-To: <20200922170526.GK32101@casper.infradead.org> References: <20200910234707.5504-1-willy@infradead.org> <20200910234707.5504-6-willy@infradead.org> <163f852ba12fd9de5dec7c4a2d6b6c7cdb379ebc.camel@redhat.com> <20200922170526.GK32101@casper.infradead.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, 2020-09-22 at 18:05 +0100, Matthew Wilcox wrote: > On Tue, Sep 22, 2020 at 12:23:45PM -0400, Qian Cai wrote: > > On Fri, 2020-09-11 at 00:47 +0100, Matthew Wilcox (Oracle) wrote: > > > Size the uptodate array dynamically to support larger pages in the > > > page cache. With a 64kB page, we're only saving 8 bytes per page today, > > > but with a 2MB maximum page size, we'd have to allocate more than 4kB > > > per page. Add a few debugging assertions. > > > > > > Signed-off-by: Matthew Wilcox (Oracle) > > > Reviewed-by: Dave Chinner > > > > Some syscall fuzzing will trigger this on powerpc: > > > > .config: https://gitlab.com/cailca/linux-mm/-/blob/master/powerpc.config > > > > [ 8805.895344][T445431] WARNING: CPU: 61 PID: 445431 at fs/iomap/buffered- > > io.c:78 iomap_page_release+0x250/0x270 > > Well, I'm glad it triggered. That warning is: > WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) != > PageUptodate(page)); > so there was definitely a problem of some kind. > > truncate_cleanup_page() calls > do_invalidatepage() calls > iomap_invalidatepage() calls > iomap_page_release() > > Is this the first warning? I'm wondering if maybe there was an I/O error > earlier which caused PageUptodate to get cleared again. If it's easy to > reproduce, perhaps you could try something like this? Yes, this is the first warning. BTW, I did run the reproducer of a805c111650c ("iomap: fix WARN_ON_ONCE() from unprivileged users") earlier, so I am wondering if this is just another victim WARN_ON_ONCE() from it. > > +void dump_iomap_page(struct page *page, const char *reason) > +{ > + struct iomap_page *iop = to_iomap_page(page); > + unsigned int nr_blocks = i_blocks_per_page(page->mapping->host, page); > + > + dump_page(page, reason); > + if (iop) > + printk("iop:reads %d writes %d uptodate %*pb\n", > + atomic_read(&iop->read_bytes_pending), > + atomic_read(&iop->write_bytes_pending), > + nr_blocks, iop->uptodate); > + else > + printk("iop:none\n"); > +} > > and then do something like: > > if (bitmap_full(iop->uptodate, nr_blocks) != PageUptodate(page)) > dump_iomap_page(page, NULL); >