Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757606AbZF3BmB (ORCPT ); Mon, 29 Jun 2009 21:42:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751727AbZF3Bly (ORCPT ); Mon, 29 Jun 2009 21:41:54 -0400 Received: from hera.kernel.org ([140.211.167.34]:39152 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751486AbZF3Blx (ORCPT ); Mon, 29 Jun 2009 21:41:53 -0400 Message-ID: <4A496D4B.3040608@kernel.org> Date: Mon, 29 Jun 2009 18:41:31 -0700 From: Yinghai Lu User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Linus Torvalds , Mikael Pettersson CC: "H. Peter Anvin" , Ingo Molnar , Matthew Wilcox , Grant Grundler , Linux Kernel Mailing List , linux-pci@vger.kernel.org Subject: Re: [BUG 2.6.31-rc1] HIGHMEM64G causes hang in PCI init on 32-bit x86 References: <200906261559.n5QFxJH8027336@pilspetsen.it.uu.se> <19013.29264.623540.275538@pilspetsen.it.uu.se> <4A45A5C1.5080701@zytor.com> <19013.59956.144640.331854@pilspetsen.it.uu.se> <20090629022911.GC20297@lackof.org> <4A484A8A.9020704@zytor.com> <19016.41349.636663.515540@pilspetsen.it.uu.se> <20090629112155.GJ5480@parisc-linux.org> <19016.44061.600652.676183@pilspetsen.it.uu.se> <4A490804.3040609@zytor.com> <4A494478.7020304@kernel.org> <4A494E3C.70304@kernel.org> <4A495C0D.2020807@zytor.com> <4A4966EF.6010809@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3454 Lines: 112 Linus Torvalds wrote: > > On Mon, 29 Jun 2009, Yinghai Lu wrote: >> + end = round_up(start, ram_alignment(start)) - 1; >> + if (start > (resource_size_t)end) >> continue; >> - reserve_region_with_split(&iomem_resource, start, >> - end - 1, "RAM buffer"); >> + reserve_region_with_split(&iomem_resource, (resource_size_t)start, >> + (resource_size_t)end, "RAM buffer"); > > Hmm. You shouldn't need the casts with reserve_region_with_split(), and > they just make things uglier. > > Also, I wonder if we should do something like this instead > > #define MAX_RESOURCE_SIZE ((resource_size_t)-1) > > ... > end = round_up(start, ram_alignment(start)) - 1; > if (end > MAX_RESOURCE_SIZE) > end = MAX_RESOURCE_SIZE; > if (start > end) > continue; > > Because otherwise we'll just be ignoring resources that cross the resource > size boundary, which sounds wrong. > > We _could_ have a RAM resource that crosses the 4GB boundary, after all. > > Yeah, it doesn't happen much in practice, because usually the 3G-4G range > is left for PCI mappings etc, so we might never hit this in practice, but > still, this sounds like a more correct thing to do. > > It also avoids the cast. We simply cap the end to the max that > 'resource_size_t' can hold. Mikael, please try this on your system, and send out /proc/iomem Thanks Yinghai [PATCH] x86: add boundary check for 32bit res before expand e820 resource to alignment fix hang with HIGHMEM_64G and 32bit resource. according to hpa and Linus, use (resource_size_t)-1 to fend off big ranges. Signed-off-by: Yinghai Lu --- arch/x86/kernel/e820.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) Index: linux-2.6/arch/x86/kernel/e820.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/e820.c +++ linux-2.6/arch/x86/kernel/e820.c @@ -1367,9 +1367,9 @@ void __init e820_reserve_resources(void) } /* How much should we pad RAM ending depending on where it is? */ -static unsigned long ram_alignment(resource_size_t pos) +static u64 ram_alignment(u64 pos) { - unsigned long mb = pos >> 20; + u64 mb = pos >> 20; /* To 64kB in the first megabyte */ if (!mb) @@ -1383,6 +1383,8 @@ static unsigned long ram_alignment(resou return 32*1024*1024; } +#define MAX_RESOURCE_SIZE ((resource_size_t)-1) + void __init e820_reserve_resources_late(void) { int i; @@ -1400,17 +1402,19 @@ void __init e820_reserve_resources_late( * avoid stolen RAM: */ for (i = 0; i < e820.nr_map; i++) { - struct e820entry *entry = &e820_saved.map[i]; - resource_size_t start, end; + struct e820entry *entry = &e820.map[i]; + u64 start, end; if (entry->type != E820_RAM) continue; start = entry->addr + entry->size; - end = round_up(start, ram_alignment(start)); - if (start == end) + end = round_up(start, ram_alignment(start)) - 1; + if (end > MAX_RESOURCE_SIZE) + end = MAX_RESOURCE_SIZE; + if (start > end) continue; - reserve_region_with_split(&iomem_resource, start, - end - 1, "RAM buffer"); + reserve_region_with_split(&iomem_resource, start, end, + "RAM buffer"); } } -- 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/