Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752811Ab0DIDMV (ORCPT ); Thu, 8 Apr 2010 23:12:21 -0400 Received: from claw.goop.org ([74.207.240.146]:37471 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752055Ab0DIDMU (ORCPT ); Thu, 8 Apr 2010 23:12:20 -0400 Message-ID: <4BBE9B12.1070209@goop.org> Date: Thu, 08 Apr 2010 20:12:18 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc12 Lightning/1.0b2pre Thunderbird/3.0.4 MIME-Version: 1.0 To: Liang Li CC: linux-kernel@vger.kernel.org, wangchen@cn.fujitsu.com, mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, yinghai@kernel.org, akpm@linux-foundation.org, jeremy.fitzhardinge@citrix.com, konrad.wilk@oracle.com Subject: Re: [PATCH v3] x86: let 'reservetop' functioning right References: <1270773835-2689-1-git-send-email-liang.li@windriver.com> In-Reply-To: <1270773835-2689-1-git-send-email-liang.li@windriver.com> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4027 Lines: 109 On 04/08/2010 05:43 PM, Liang Li wrote: > When specify 'reservetop=0xbadc0de' kernel parameter, the kernel will > stop booting due to a early_ioremap bug that relate to commit 8827247ff. > > The root cause of boot failure problem is the value of 'slot_virt[i]' > was initialized in setup_arch->early_ioremap_init. But later in > setup_arch, the function 'parse_early_param' will modify 'FIXADDR_TOP' > when 'reservetop=0xbadc0de' being specified. > > The simplest fix might be use __fix_to_virt(idx0) to get updated value > of 'FIXADDR_TOP' in '__early_ioremap' instead of reference old value > from slot_virt[slot] directly. > While I guess this patch works OK, I have to say that I'm worried by the need for it at all; it seems to be papering over a more serious problem. reserve_top_address() is supposed to be called very early, before anything has used or referenced FIXADDR_TOP. If we're seeing problems with FIXADDR_TOP changing after it has been used, then it means that reserve_top_address() is being called too late. Fixing that would be the real fix. J > Changelog since v0: > > -v1: When reservetop being handled then FIXADDR_TOP get adjusted, Hence > check prev_map then re-initialize slot_virt and PMD based on new > FIXADDR_TOP. > > -v2: place fixup_early_ioremap hence call early_ioremap_init in > reserve_top_address to re-initialize slot_virt and corresponding PMD > when parse_reservetop > > -v3: move fixup_early_ioremap out of reserve_top_address to make sure > other clients of reserve_top_address like xen/lguest won't broken > > Signed-off-by: Liang Li > Cc: Wang Chen > Cc: Ingo Molnar > Cc: Thomas Gleixner > Cc: "H. Peter Anvin" > Cc: Yinghai Lu > Cc: Andrew Morton > Acked-by: Jeremy Fitzhardinge > Tested-by: Konrad Rzeszutek Wilk > --- > arch/x86/include/asm/io.h | 1 + > arch/x86/mm/ioremap.c | 15 +++++++++++++++ > arch/x86/mm/pgtable_32.c | 1 + > 3 files changed, 17 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h > index a1dcfa3..30a3e97 100644 > --- a/arch/x86/include/asm/io.h > +++ b/arch/x86/include/asm/io.h > @@ -347,6 +347,7 @@ extern void __iomem *early_ioremap(resource_size_t phys_addr, > extern void __iomem *early_memremap(resource_size_t phys_addr, > unsigned long size); > extern void early_iounmap(void __iomem *addr, unsigned long size); > +extern void fixup_early_ioremap(void); > > #define IO_SPACE_LIMIT 0xffff > > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c > index 5eb1ba7..e4ab706 100644 > --- a/arch/x86/mm/ioremap.c > +++ b/arch/x86/mm/ioremap.c > @@ -448,6 +448,21 @@ static inline void __init early_clear_fixmap(enum fixed_addresses idx) > static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata; > static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata; > > +void __init fixup_early_ioremap(void) > +{ > + int i; > + for (i = 0; i < FIX_BTMAPS_SLOTS; i++) { > + if (prev_map[i]) > + break; > + } > + > + if (i < FIX_BTMAPS_SLOTS) > + BUG_ON(1); > + > + early_ioremap_init(); > + return; > +} > + > static int __init check_early_ioremap_leak(void) > { > int count = 0; > diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c > index 1a8faf0..26eadaa 100644 > --- a/arch/x86/mm/pgtable_32.c > +++ b/arch/x86/mm/pgtable_32.c > @@ -128,6 +128,7 @@ static int __init parse_reservetop(char *arg) > > address = memparse(arg, &arg); > reserve_top_address(address); > + fixup_early_ioremap(); > return 0; > } > early_param("reservetop", parse_reservetop); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/