Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753275AbeAJLQn (ORCPT + 1 other); Wed, 10 Jan 2018 06:16:43 -0500 Received: from mga06.intel.com ([134.134.136.31]:9210 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751694AbeAJLQl (ORCPT ); Wed, 10 Jan 2018 06:16:41 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,339,1511856000"; d="scan'208";a="8977143" Date: Wed, 10 Jan 2018 14:16:04 +0300 From: "Kirill A. Shutemov" To: Dave Young Cc: "Kirill A. Shutemov" , Baoquan He , Ingo Molnar , Mike Galbraith , Andrew Morton , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Andy Lutomirski , Borislav Petkov , Cyrill Gorcunov , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , linux-mm@kvack.org, Vivek Goyal , kexec@lists.infradead.org Subject: Re: [PATCH 4.14 023/159] mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y Message-ID: <20180110111603.56disgew7ipusgjy@black.fi.intel.com> References: <20171222084625.007160464@linuxfoundation.org> <1515302062.6507.18.camel@gmx.de> <20180108160444.2ol4fvgqbxnjmlpg@gmail.com> <20180108174653.7muglyihpngxp5tl@black.fi.intel.com> <20180109001303.dy73bpixsaegn4ol@node.shutemov.name> <20180109010927.GA2082@dhcp-128-65.nay.redhat.com> <20180109054131.GB1935@localhost.localdomain> <20180109072440.GA6521@dhcp-128-65.nay.redhat.com> <20180109090552.45ddfk2y25lf4uyn@node.shutemov.name> <20180110030804.GB1744@dhcp-128-110.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180110030804.GB1744@dhcp-128-110.nay.redhat.com> User-Agent: NeoMutt/20170714-126-deb55f (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Wed, Jan 10, 2018 at 03:08:04AM +0000, Dave Young wrote: > On Tue, Jan 09, 2018 at 12:05:52PM +0300, Kirill A. Shutemov wrote: > > On Tue, Jan 09, 2018 at 03:24:40PM +0800, Dave Young wrote: > > > On 01/09/18 at 01:41pm, Baoquan He wrote: > > > > On 01/09/18 at 09:09am, Dave Young wrote: > > > > > > > > > As for the macro name, VMCOREINFO_SYMBOL_ARRAY sounds better. > > > > Yep, that's better. > > > > > > I still think using vmcoreinfo_append_str is better. Unless we replace > > > > all array variables with the newly added macro. > > > > > > > > vmcoreinfo_append_str("SYMBOL(mem_section)=%lx\n", > > > > (unsigned long)mem_section); > > > > > > I have no strong opinion, either change all array uses or just introduce > > > the macro and start to use it from now on if we have similar array > > > symbols. > > > > Do you need some action on my side or will you folks take care about this? > > I think Baoquan was suggesting to update all array users in current > code, if you can check every VMCOREINFO_SYMBOL and update all the arrays > he will be happy. But if can not do it easily I'm fine with a > VMCOREINFO_SYMBOL_ARRAY changes only now, we kdump people can do it > later as well. It seems it's the only array we have there. swapper_pg_dir is a potential candidate, but it's 'unsigned long' on arm. Below it patch with corrected macro name. Please, consider applying. >From 70f3a84b97f2de98d1364f7b10b7a42a1d8e9968 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Tue, 9 Jan 2018 02:55:47 +0300 Subject: [PATCH] kdump: Write a correct address of mem_section into vmcoreinfo Depending on configuration mem_section can now be an array or a pointer to an array allocated dynamically. In most cases, we can continue to refer to it as 'mem_section' regardless of what it is. But there's one exception: '&mem_section' means "address of the array" if mem_section is an array, but if mem_section is a pointer, it would mean "address of the pointer". We've stepped onto this in kdump code. VMCOREINFO_SYMBOL(mem_section) writes down address of pointer into vmcoreinfo, not array as we wanted. Let's introduce VMCOREINFO_SYMBOL_ARRAY() that would handle the situation correctly for both cases. Signed-off-by: Kirill A. Shutemov Fixes: 83e3c48729d9 ("mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y") --- include/linux/crash_core.h | 2 ++ kernel/crash_core.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index 06097ef30449..b511f6d24b42 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -42,6 +42,8 @@ phys_addr_t paddr_vmcoreinfo_note(void); vmcoreinfo_append_str("PAGESIZE=%ld\n", value) #define VMCOREINFO_SYMBOL(name) \ vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name) +#define VMCOREINFO_SYMBOL_ARRAY(name) \ + vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)name) #define VMCOREINFO_SIZE(name) \ vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \ (unsigned long)sizeof(name)) diff --git a/kernel/crash_core.c b/kernel/crash_core.c index b3663896278e..4f63597c824d 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -410,7 +410,7 @@ static int __init crash_save_vmcoreinfo_init(void) VMCOREINFO_SYMBOL(contig_page_data); #endif #ifdef CONFIG_SPARSEMEM - VMCOREINFO_SYMBOL(mem_section); + VMCOREINFO_SYMBOL_ARRAY(mem_section); VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); VMCOREINFO_STRUCT_SIZE(mem_section); VMCOREINFO_OFFSET(mem_section, section_mem_map); -- Kirill A. Shutemov