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 9D105EB64D7 for ; Wed, 28 Jun 2023 17:11:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231655AbjF1RLW (ORCPT ); Wed, 28 Jun 2023 13:11:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231126AbjF1RLA (ORCPT ); Wed, 28 Jun 2023 13:11:00 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6A4210C for ; Wed, 28 Jun 2023 10:10:57 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-56cf9a86277so360427b3.3 for ; Wed, 28 Jun 2023 10:10:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1687972257; x=1690564257; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=8hBGoSmAipjb7uFaXgommTCgThqhf3N/MwIcztkSaf0=; b=LKSYSGBSIRpYNWo6GB3fAX7Sp7LGTqtVknZjcmaruG6ULOl4SWX3oMH6i1meJ7Jc7h FQ429XW5BEHayOaB/G+854ylw3GR7iowaxfbA1xFNokKPSfZU9qHK8I56VYb3cj8v3Im 45og0RH/taCs9T6G0wgZA+ZvGKFqM1dg8NtbsIkZV4SfXADT8WOBUrRVnR+Zm4s8RAaz L1yZuP/h04SwgiLgw/XhRTH6aFoMtzqLI2jNnU/1vQzPQvGtZzT2jgG0IfoYr8+mTB61 /6ygnTJiq0wZgf6c3XYT7MrTU9iIeg//d3keWlxl8gQY1GX+VQQyb5ID7ENUwO9M5Nw6 BwsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687972257; x=1690564257; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8hBGoSmAipjb7uFaXgommTCgThqhf3N/MwIcztkSaf0=; b=fIg8Yr8XsT+HMxo3BUPBnuiaBWOzsFEDxPKmtL331dhVIuwoCAQjksM7A7mR+mDP+u dCfGiLgwYrzr7M4yfDaR9crwQrEF4AbgVT08Iwe4ULypflWMGxTZe2bhl/0kBGflwHyB vGb8KlRc0NomQDioeB+d6a9KG/YNTEJtN0Ia/nm19KA9fXO6VdtvO2SudsW1oE/oXaap BkMtISCFrzb+ND4oMtNrxTzOxJ+kiGi37TNzwMup7+0paxiL6fxEmgszZW2INQvukXWr J4CAtpmyMpAEKmqO+mnHjhN+PQbJNSUVhIvCpIssmfyCHaFMZcQqR3yPvezywtKueVml NNUw== X-Gm-Message-State: AC+VfDytCVhq+tGYYfrK0KFzsSWbJCoahJ8BYbxiffLj/wQP+QJPFNut cRGayzt7a2IejxstjziGLAdy+dy5looUF685xQ== X-Google-Smtp-Source: ACHHUZ537w0kvhE6ZiJ53ujP+GdQhdrmWEWLOQ3XFca0OfxDBa47iNnq2FuExHLMS2z28CiKkkkGNs1j3Za/uWd1MQ== X-Received: from yuxiao.svl.corp.google.com ([2620:15c:2a3:200:ee8e:ae51:26:66dc]) (user=yuxiaozhang job=sendgmr) by 2002:a81:ae07:0:b0:570:200:18e1 with SMTP id m7-20020a81ae07000000b00570020018e1mr14077449ywh.3.1687972257123; Wed, 28 Jun 2023 10:10:57 -0700 (PDT) Date: Wed, 28 Jun 2023 10:10:55 -0700 In-Reply-To: <2023062832-barrier-strenuous-9499@gregkh> Mime-Version: 1.0 References: <2023062832-barrier-strenuous-9499@gregkh> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230628171055.1312737-1-yuxiaozhang@google.com> Subject: Re: Re: [PATCH] pstore: ramoops: support pmsg size larger than kmalloc limitation From: Yuxiao Zhang To: Greg KH Cc: Kees Cook , Tony Luck , "'Guilherme G . Piccoli'" , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, wak@google.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks for reviewing the patch. On 28 Jun 2023 07:30:16 +0200, Greg KH wrote: >What is that max size? The max size is arch dependent, it should be 2^(PAGE_SIZE+MAX_ORDER). In our environment it is 4M. >what in-kernel user is hitting this in the pstore implementation? We are trying to use pmsg to hold a core dump file, so we have pmsg-size=32M and thus hit this issue. Other than us, here is one I found that trying to save dmesg beyond kmalloc limitaton: https://lore.kernel.org/lkml/b2d66d9f-15a6-415c-2485-44649027a1d5@igalia.com/T/ Thanks, -Yuxiao Zhang