From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 08AF56B0078 for ; Fri, 5 Mar 2010 20:51:56 -0500 (EST) Message-ID: <4B91B4EF.5090502@kernel.org> Date: Fri, 05 Mar 2010 17:50:39 -0800 From: Yinghai Lu MIME-Version: 1.0 Subject: Re: mmotm boot panic bootmem-avoid-dma32-zone-by-default.patch References: <49b004811003041321g2567bac8yb73235be32a27e7c@mail.gmail.com> <20100305032106.GA12065@cmpxchg.org> <49b004811003042117n720f356h7e10997a1a783475@mail.gmail.com> <4B915074.4020704@kernel.org> <20100305235812.GA15249@cmpxchg.org> In-Reply-To: <20100305235812.GA15249@cmpxchg.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Johannes Weiner Cc: Greg Thelen , Andrew Morton , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" List-ID: On 03/05/2010 03:58 PM, Johannes Weiner wrote: > 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. that depends on every arch maintainer. user can compare them on x86 to check if... next step will be make fw_mem_map to generiaized and combine them with lmb. > > 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? just let caller set the goal. > >> 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. I am trying to avoid the second call. please check another patch about "introduce bootmem_default_goal : don't punish 64bit system without 4g ram" > > 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? ok. Thanks Yinghai -- 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