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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 D9070C282C8 for ; Mon, 28 Jan 2019 14:45:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A47522171F for ; Mon, 28 Jan 2019 14:45:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548686726; bh=R4LUADSyGzbKRrmHJJdrrtmnh1hqwyHHtyZMh/+etHY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HaRKGY/9PNnpQCWBxTrnNjAbdiAa1eWZdhDeqtDiyNtvM4fDnf5kYtt7jakEXF06B GTiEq9Ehi1FgjGvXYiu+c2AjOBoLyEpM9HECl8dWotCsHco0DWEfANapShoIY2iyLu JLVzT5f7nuprldE3L5LjH3CjoSFooYJRsSk2DXJ8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726972AbfA1OpY (ORCPT ); Mon, 28 Jan 2019 09:45:24 -0500 Received: from mail-ed1-f67.google.com ([209.85.208.67]:40952 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726693AbfA1OpT (ORCPT ); Mon, 28 Jan 2019 09:45:19 -0500 Received: by mail-ed1-f67.google.com with SMTP id g22so13190509edr.7 for ; Mon, 28 Jan 2019 06:45:17 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=nTySQcXDgbgWvZzIuOomkfESKJ+ZiRRspPXpQ++HP0Y=; b=dctjK6wIV7a7Oc7qU/081YuM6vdYgnoOE/5cF/uDSIzLcXQYHWtsgybP1JsxJJ47ER en26HEgmSeYGvdlgNGHsNDh8+6ualSavZFfXFF3UQyNuaT/CBjvdB1bvgS6yB3uSkRIh M8LteJpYH/AdGQjwSadXFohld79HAq82fabWUdrGD7kUax/q+iHMlR/cvZSfhZ8ViDtU zT5f7FE4WeYP3Iyp5d11laTGWE6UClmSq38ki2S3ibj/Et4j6oNS5AMMF8X9ZoGIcMB+ zlFawrVlqSkCXQX83ddI3REThmQy9xycXbXRsNIiwGvEgNnjlW9ypv5M9lUqp+Rzdoeo hCzA== X-Gm-Message-State: AJcUukctZAoEWsweKcvPrzNHez3AdoZoYJIuJCWepxEsVm3DC88XPjhx BhCeMhtQcGXCEj0Q/O7Jnqs= X-Google-Smtp-Source: ALg8bN4SDZcBeV3rbkI2gxNZ8px9xHNMo/kDxk2X/qizXtVKHesg5Jmhm964+1jN/CWGYVmWZahd/Q== X-Received: by 2002:a50:b3b8:: with SMTP id s53mr22208336edd.122.1548686717177; Mon, 28 Jan 2019 06:45:17 -0800 (PST) Received: from tiehlicka.microfocus.com (prg-ext-pat.suse.com. [213.151.95.130]) by smtp.gmail.com with ESMTPSA id j8sm2919064ejr.17.2019.01.28.06.45.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 06:45:16 -0800 (PST) From: Michal Hocko To: Mikhail Zaslonko , Mikhail Gavrilov Cc: Andrew Morton , Pavel Tatashin , schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, gerald.schaefer@de.ibm.com, , LKML , Michal Hocko Subject: [PATCH 2/2] mm, memory_hotplug: test_pages_in_a_zone do not pass the end of zone Date: Mon, 28 Jan 2019 15:45:06 +0100 Message-Id: <20190128144506.15603-3-mhocko@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190128144506.15603-1-mhocko@kernel.org> References: <20190128144506.15603-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mikhail Zaslonko If memory end is not aligned with the sparse memory section boundary, the mapping of such a section is only partly initialized. This may lead to VM_BUG_ON due to uninitialized struct pages access from test_pages_in_a_zone() function triggered by memory_hotplug sysfs handlers. Here are the the panic examples: CONFIG_DEBUG_VM_PGFLAGS=y kernel parameter mem=2050M -------------------------- page:000003d082008000 is uninitialized and poisoned page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) Call Trace: ([<0000000000385b26>] test_pages_in_a_zone+0xde/0x160) [<00000000008f15c4>] show_valid_zones+0x5c/0x190 [<00000000008cf9c4>] dev_attr_show+0x34/0x70 [<0000000000463ad0>] sysfs_kf_seq_show+0xc8/0x148 [<00000000003e4194>] seq_read+0x204/0x480 [<00000000003b53ea>] __vfs_read+0x32/0x178 [<00000000003b55b2>] vfs_read+0x82/0x138 [<00000000003b5be2>] ksys_read+0x5a/0xb0 [<0000000000b86ba0>] system_call+0xdc/0x2d8 Last Breaking-Event-Address: [<0000000000385b26>] test_pages_in_a_zone+0xde/0x160 Kernel panic - not syncing: Fatal exception: panic_on_oops Fix this by checking whether the pfn to check is within the zone. [mhocko@suse.com: separated this change from http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com] Signed-off-by: Mikhail Zaslonko Signed-off-by: Michal Hocko --- mm/memory_hotplug.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 07872789d778..7711d0e327b6 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1274,6 +1274,9 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn, i++; if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn) continue; + /* Check if we got outside of the zone */ + if (zone && !zone_spans_pfn(zone, pfn + i)) + return 0; page = pfn_to_page(pfn + i); if (zone && page_zone(page) != zone) return 0; -- 2.20.1