From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 30ACE6B0047 for ; Fri, 5 Mar 2010 18:58:47 -0500 (EST) Date: Sat, 6 Mar 2010 00:58:12 +0100 From: Johannes Weiner Subject: Re: mmotm boot panic bootmem-avoid-dma32-zone-by-default.patch Message-ID: <20100305235812.GA15249@cmpxchg.org> References: <49b004811003041321g2567bac8yb73235be32a27e7c@mail.gmail.com> <20100305032106.GA12065@cmpxchg.org> <49b004811003042117n720f356h7e10997a1a783475@mail.gmail.com> <4B915074.4020704@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B915074.4020704@kernel.org> Sender: owner-linux-mm@kvack.org To: Yinghai Lu Cc: Greg Thelen , Andrew Morton , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" List-ID: Hello Yinghai, On Fri, Mar 05, 2010 at 10:41:56AM -0800, Yinghai Lu wrote: > On 03/04/2010 09:17 PM, Greg Thelen wrote: > > On Thu, Mar 4, 2010 at 7:21 PM, Johannes Weiner wrote: > >> On Thu, Mar 04, 2010 at 01:21:41PM -0800, Greg Thelen wrote: > >>> On several systems I am seeing a boot panic if I use mmotm > >>> (stamp-2010-03-02-18-38). If I remove > >>> bootmem-avoid-dma32-zone-by-default.patch then no panic is seen. I > >>> find that: > >>> * 2.6.33 boots fine. > >>> * 2.6.33 + mmotm w/o bootmem-avoid-dma32-zone-by-default.patch: boots fine. > >>> * 2.6.33 + mmotm (including > >>> bootmem-avoid-dma32-zone-by-default.patch): panics. > ... > > > > Note: mmotm has been recently updated to stamp-2010-03-04-18-05. I > > re-tested with 'make defconfig' to confirm the panic with this later > > mmotm. > > please check > > [PATCH] early_res: double check with updated goal in alloc_memory_core_early > > Johannes Weiner pointed out that new early_res replacement for alloc_bootmem_node > change the behavoir about goal. > original bootmem one will try go further regardless of goal. > > and it will break his patch about default goal from MAX_DMA to MAX_DMA32... > also broke uncommon machines with <=16M of memory. > (really? our x86 kernel still can run on 16M system?) > > so try again with update goal. Thanks for the patch, it seems to be correct. However, I have a more generic question about it, regarding the future of the early_res allocator. Did you plan on keeping the bootmem API for longer? Because my impression was, emulating it is a temporary measure until all users are gone and bootmem can be finally dropped. But then this would require some sort of handling of 'user does not need DMA[32] memory, so avoid it' and 'user can only use DMA[32] memory' in the early_res allocator as well. I ask this specifically because you move this fix into the bootmem compatibility code while there is not yet a way to tell early_res the same thing, so switching a user that _needs_ to specify this requirement from bootmem to early_res is not yet possible, is it? > Reported-by: Greg Thelen > Signed-off-by: Yinghai Lu > > --- > mm/bootmem.c | 28 +++++++++++++++++++++++++--- > 1 file changed, 25 insertions(+), 3 deletions(-) > > Index: linux-2.6/mm/bootmem.c > =================================================================== > --- linux-2.6.orig/mm/bootmem.c > +++ linux-2.6/mm/bootmem.c > @@ -170,6 +170,28 @@ void __init free_bootmem_late(unsigned l > } > > #ifdef CONFIG_NO_BOOTMEM > +static void * __init ___alloc_memory_core_early(pg_data_t *pgdat, u64 size, > + u64 align, u64 goal, u64 limit) > +{ > + void *ptr; > + unsigned long end_pfn; > + > + ptr = __alloc_memory_core_early(pgdat->node_id, size, align, > + goal, limit); > + if (ptr) > + return ptr; > + > + /* check goal according */ > + end_pfn = pgdat->node_start_pfn + pgdat->node_spanned_pages; > + if ((end_pfn << PAGE_SHIFT) < (goal + size)) { > + goal = pgdat->node_start_pfn << PAGE_SHIFT; > + ptr = __alloc_memory_core_early(pgdat->node_id, size, align, > + goal, limit); > + } > + > + return ptr; I think it would make sense to move the parameter check before doing the allocation. Then you save the second call. And a second nitpick: naming the inner function __foo and the outer one ___foo seems confusing to me. Could you maybe rename the wrapper? bootmem_compat_alloc_early() or something like that? Thanks, Hannes -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org