Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751828Ab0DHCUe (ORCPT ); Wed, 7 Apr 2010 22:20:34 -0400 Received: from mail.windriver.com ([147.11.1.11]:57538 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750878Ab0DHCUb (ORCPT ); Wed, 7 Apr 2010 22:20:31 -0400 Date: Thu, 8 Apr 2010 10:18:07 +0800 From: Liang Li To: Yinghai Cc: akpm@linux-foundation.org, hpa@zytor.com, mingo@elte.hu, tglx@linutronix.de, wangchen@cn.fujitsu.com, "linux-kernel@vger.kernel.org" Subject: Re: + x86-fix-handling-of-the-reservetop-boot-option.patch added to -mm tree Message-ID: <20100408021807.GA26543@localhost> Reply-To: Liang Li References: <201004072200.o37M0d19009878@imap1.linux-foundation.org> <4BBD1AA3.4000204@oracle.com> <20100408010558.GA4053@localhost> <4BBD2DD4.1060101@oracle.com> <20100408015353.GB4053@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100408015353.GB4053@localhost> User-Agent: Mutt/1.5.20 (2009-08-17) X-OriginalArrivalTime: 08 Apr 2010 02:19:26.0726 (UTC) FILETIME=[E974D260:01CAD6C1] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6219 Lines: 151 On Thu, Apr 08, 2010 at 09:53:53AM +0800, Liang Li wrote: > On Wed, Apr 07, 2010 at 06:13:56PM -0700, Yinghai wrote: > > On 04/07/2010 06:05 PM, Liang Li wrote: > > > On Wed, Apr 07, 2010 at 04:52:03PM -0700, Yinghai wrote: > > >> On 04/07/2010 03:00 PM, akpm@linux-foundation.org wrote: > > >>> The patch titled > > >>> x86: fix handling of the 'reservetop' boot option > > >>> has been added to the -mm tree. Its filename is > > >>> x86-fix-handling-of-the-reservetop-boot-option.patch > > >>> > > >>> Before you just go and hit "reply", please: > > >>> a) Consider who else should be cc'ed > > >>> b) Prefer to cc a suitable mailing list as well > > >>> c) Ideally: find the original patch on the mailing list and do a > > >>> reply-to-all to that, adding suitable additional cc's > > >>> > > >>> *** Remember to use Documentation/SubmitChecklist when testing your code *** > > >>> > > >>> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find > > >>> out what to do about this > > >>> > > >>> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ > > >>> > > >>> ------------------------------------------------------ > > >>> Subject: x86: fix handling of the 'reservetop' boot option > > >>> From: Liang Li > > >>> > > >>> When specifying the 'reservetop=0xbadc0de' kernel parameter, the kernel > > >>> will stop booting due to a early_ioremap bug that relate to commit > > >>> 8827247ff ("x86: don't define __this_fixmap_does_not_exist()"). > > >>> > > >>> 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. > > >>> > > >>> Signed-off-by: Liang Li > > >>> Cc: Wang Chen > > >>> Cc: Ingo Molnar > > >>> Cc: Thomas Gleixner > > >>> Cc: "H. Peter Anvin" > > >>> Cc: Yinghai Lu > > >>> Signed-off-by: Andrew Morton > > >>> --- > > >>> > > >>> arch/x86/mm/ioremap.c | 4 ++-- > > >>> 1 file changed, 2 insertions(+), 2 deletions(-) > > >>> > > >>> diff -puN arch/x86/mm/ioremap.c~x86-fix-handling-of-the-reservetop-boot-option arch/x86/mm/ioremap.c > > >>> --- a/arch/x86/mm/ioremap.c~x86-fix-handling-of-the-reservetop-boot-option > > >>> +++ a/arch/x86/mm/ioremap.c > > >>> @@ -537,9 +537,9 @@ __early_ioremap(resource_size_t phys_add > > >>> --nrpages; > > >>> } > > >>> if (early_ioremap_debug) > > >>> - printk(KERN_CONT "%08lx + %08lx\n", offset, slot_virt[slot]); > > >>> + printk(KERN_CONT "%08lx + %08lx\n", offset, __fix_to_virt(idx0)); > > >>> > > >>> - prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]); > > >>> + prev_map[slot] = (void __iomem *)(offset + __fix_to_virt(idx0)); > > >>> return prev_map[slot]; > > >>> } > > >>> > > >>> _ > > >> > > >> not that simple. but it looks like correct direction. > > >> > > >> please consider: > > >> when early_parsing reserve_top, double check if there is left over in prev_map[], and > > >> reinitialize slot_virt[] and clear old PMD and setup new PMD if needed. > > > > > > Hi Yinghai, > > > > > > Thanks for your reply, its better to have eyes on then being ignored. :) > > > > > > Your suggestions were considered before the patch to public, let me try > > > to explain: > > > > > > #1 check/adjust prev_map[]? > > > In my tests, seems early_ioremap is untouched between early_ioremap_init > > > and parse_early_param so I did not check prev_map. Even its get touched, > > > I think we could do nothing to this mapping, since prev_map[i] just > > > record virt addr for clients of early_ioremap. We can check and adjust > > > prev_map but clients of early_ioremap won't realize the fact so nothing > > > being fixed or broken. > > > > efi related code need them > > > > dmi > > > > you need to add bug_on if there is still have left over, and need the caller to re map it again later. > > > > > > > > #2 reinitialize slot_virt and update PMD > > > I actually tried this approach, call early_ioremap_init again after > > > parse_early_param will do that work, it also works but I am not sure > > > that is the better solution or too heavy for solve the problem? So I > > > tend to say 'simplest' solution in git commit log. > > > > how about PMD? you don't need set PMD again. > > > > YH > > Hi Yinghai, > > Does this similar modification like this is more preferred? > > 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 ea82ef0..fe06296 100644 > --- a/arch/x86/mm/ioremap.c > +++ b/arch/x86/mm/ioremap.c > @@ -448,6 +448,23 @@ 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) > + WARN_ON(1); Should be: if (i < FIX_BTMAPS_SLOTS) WARN_ON(1); -- 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/