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=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 E4E8FC3A59E for ; Sat, 17 Aug 2019 03:57:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A9ED32173B for ; Sat, 17 Aug 2019 03:57:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="PLgTwvnO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9ED32173B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 456126B0007; Fri, 16 Aug 2019 23:57:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 405E56B000A; Fri, 16 Aug 2019 23:57:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 31C276B000C; Fri, 16 Aug 2019 23:57:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id 113306B0007 for ; Fri, 16 Aug 2019 23:57:58 -0400 (EDT) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 9AF511E06F for ; Sat, 17 Aug 2019 03:57:57 +0000 (UTC) X-FDA: 75830561394.19.tramp25_2832c76ddb72d X-HE-Tag: tramp25_2832c76ddb72d X-Filterd-Recvd-Size: 4605 Received: from mail-ot1-f66.google.com (mail-ot1-f66.google.com [209.85.210.66]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Sat, 17 Aug 2019 03:57:56 +0000 (UTC) Received: by mail-ot1-f66.google.com with SMTP id c34so11436349otb.7 for ; Fri, 16 Aug 2019 20:57:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5JkAhLV4VoRnu2crZGL/J2yHThD4/hsSp7D/mpQ+b1s=; b=PLgTwvnO1F/glwSZqKSngpyzUq0vFd7nv9qzk0tkt39wZ4ihb11tnzHU/LqfTd0yVJ axw13Ep9GpgY89HHCRMt5qUEKZjV9fpXHekdl9moJRSsSmy+onoBfwnsmjsxfxgdFpuF UY5cJrgDOiWiNiT1c8BfhSIr6K4z3xB0kAEVeYHl0c6rrXqpT4vxHNa+wRXkaONde3aK cq2b6g1enF0XB8LwfJxyibCWbp16a+UJXk+Gury67BoYPTB3sy04w+RGXID/OjvfkmYd JEcGSzTjVP1+Q5GvY+6ZYPwGiUpU8/wluREQDwHDBdiY/jgkdG85+6s3b2IvImiQK0uj u4Uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5JkAhLV4VoRnu2crZGL/J2yHThD4/hsSp7D/mpQ+b1s=; b=rdODLwj11+OFIQb8k/tgOHDQr6jKamnMBXaSfaDpHyT0ravSxE3me4eOcm8yJ1BW89 Y8ie8vDW/Mf9f8scqrpRvM6sjRXLvRqZzq9giN9cJpVxbkje4cqTGrd6W4eWfaIlN2Iw n4ECv9ckqDG1jnJH09fJbrWpGSWZEUtgXEdVS9uqvEmRgodkxtZXOsLQkB4XpUqrISzH lvjpqDiop7p0J3EjzoegNkSSWwg6UxbrVO2BAIuoRakHOIB3bgiW9CQNucf//0IM9Ss3 EFBFh7FYaG6fxUw7sXdD1hu+xCnqdhW9hKcJ7yIgxLLuhwrDooaDXP8wnNYlcVxDh8/5 +6Ng== X-Gm-Message-State: APjAAAUOavD7vMUZQpDdjOVgPwjHEd9/q8Fg5RUDH14yjg+zHqGzHdmw +aRCU5VanIcyRSp7V4DnYyTMtEl7vejQhzRj+h2dBw== X-Google-Smtp-Source: APXvYqz/7KefU1PepmrlXbJuNHdv1LcskjRo2dk3pgYqgdNtUmZnRstkYW16mDX9ocpLJMiCLBg7bb1GGPv5FPxEOVQ= X-Received: by 2002:a05:6830:1e05:: with SMTP id s5mr9263489otr.247.1566014275232; Fri, 16 Aug 2019 20:57:55 -0700 (PDT) MIME-Version: 1.0 References: <1565991345.8572.28.camel@lca.pw> <0FB85A78-C2EE-4135-9E0F-D5623CE6EA47@lca.pw> In-Reply-To: <0FB85A78-C2EE-4135-9E0F-D5623CE6EA47@lca.pw> From: Dan Williams Date: Fri, 16 Aug 2019 20:57:40 -0700 Message-ID: Subject: Re: devm_memremap_pages() triggers a kasan_add_zero_shadow() warning To: Qian Cai Cc: Linux MM , linux-nvdimm , Linux Kernel Mailing List , Andrey Ryabinin , kasan-dev@googlegroups.com Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Aug 16, 2019 at 8:34 PM Qian Cai wrote: > > > > > On Aug 16, 2019, at 5:48 PM, Dan Williams wrote: > > > > On Fri, Aug 16, 2019 at 2:36 PM Qian Cai wrote: > >> > >> Every so often recently, booting Intel CPU server on linux-next triggers this > >> warning. Trying to figure out if the commit 7cc7867fb061 > >> ("mm/devm_memremap_pages: enable sub-section remap") is the culprit here. > >> > >> # ./scripts/faddr2line vmlinux devm_memremap_pages+0x894/0xc70 > >> devm_memremap_pages+0x894/0xc70: > >> devm_memremap_pages at mm/memremap.c:307 > > > > Previously the forced section alignment in devm_memremap_pages() would > > cause the implementation to never violate the KASAN_SHADOW_SCALE_SIZE > > (12K on x86) constraint. > > > > Can you provide a dump of /proc/iomem? I'm curious what resource is > > triggering such a small alignment granularity. > > This is with memmap=4G!4G , > > # cat /proc/iomem [..] > 100000000-155dfffff : Persistent Memory (legacy) > 100000000-155dfffff : namespace0.0 > 155e00000-15982bfff : System RAM > 155e00000-156a00fa0 : Kernel code > 156a00fa1-15765d67f : Kernel data > 157837000-1597fffff : Kernel bss > 15982c000-1ffffffff : Persistent Memory (legacy) > 200000000-87fffffff : System RAM Ok, looks like 4G is bad choice to land the pmem emulation on this system because it collides with where the kernel is deployed and gets broken into tiny pieces that violate kasan's. This is a known problem with memmap=. You need to pick an memory range that does not collide with anything else. See: https://nvdimm.wiki.kernel.org/how_to_choose_the_correct_memmap_kernel_parameter_for_pmem_on_your_system ...for more info.