From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by kanga.kvack.org (Postfix) with ESMTP id 245978E0038 for ; Tue, 8 Jan 2019 04:01:53 -0500 (EST) Received: by mail-qt1-f197.google.com with SMTP id d35so2822282qtd.20 for ; Tue, 08 Jan 2019 01:01:53 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id p184si1188085qkc.42.2019.01.08.01.01.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 08 Jan 2019 01:01:52 -0800 (PST) Date: Tue, 8 Jan 2019 17:01:38 +0800 From: Baoquan He Subject: Re: [PATCHv5] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr Message-ID: <20190108090138.GB18718@MiWiFi-R3L-srv> References: <1546848299-23628-1-git-send-email-kernelfans@gmail.com> <20190108080538.GB4396@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190108080538.GB4396@rapoport-lnx> Sender: owner-linux-mm@kvack.org List-ID: To: Mike Rapoport Cc: Pingfan Liu , linux-mm@kvack.org, kexec@lists.infradead.org, Tang Chen , "Rafael J. Wysocki" , Len Brown , Andrew Morton , Mike Rapoport , Michal Hocko , Jonathan Corbet , Yaowei Bai , Pavel Tatashin , Nicholas Piggin , Naoya Horiguchi , Daniel Vacek , Mathieu Malaterre , Stefan Agner , Dave Young , yinghai@kernel.org, vgoyal@redhat.com, linux-kernel@vger.kernel.org Hi Mike, On 01/08/19 at 10:05am, Mike Rapoport wrote: > I'm not thrilled by duplicating this code (yet again). > I liked the v3 of this patch [1] more, assuming we allow bottom-up mode to > allocate [0, kernel_start) unconditionally. > I'd just replace you first patch in v3 [2] with something like: In initmem_init(), we will restore the top-down allocation style anyway. While reserve_crashkernel() is called after initmem_init(), it's not appropriate to adjust memblock_find_in_range_node(), and we really want to find region bottom up for crashkernel reservation, no matter where kernel is loaded, better call __memblock_find_range_bottom_up(). Create a wrapper to do the necessary handling, then call __memblock_find_range_bottom_up() directly, looks better. Thanks Baoquan > > diff --git a/mm/memblock.c b/mm/memblock.c > index 7df468c..d1b30b9 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -274,24 +274,14 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size, > * try bottom-up allocation only when bottom-up mode > * is set and @end is above the kernel image. > */ > - if (memblock_bottom_up() && end > kernel_end) { > - phys_addr_t bottom_up_start; > - > - /* make sure we will allocate above the kernel */ > - bottom_up_start = max(start, kernel_end); > - > + if (memblock_bottom_up()) { > /* ok, try bottom-up allocation first */ > - ret = __memblock_find_range_bottom_up(bottom_up_start, end, > + ret = __memblock_find_range_bottom_up(start, end, > size, align, nid, flags); > if (ret) > return ret; > > /* > - * we always limit bottom-up allocation above the kernel, > - * but top-down allocation doesn't have the limit, so > - * retrying top-down allocation may succeed when bottom-up > - * allocation failed. > - * > * bottom-up allocation is expected to be fail very rarely, > * so we use WARN_ONCE() here to see the stack trace if > * fail happens. > > [1] https://lore.kernel.org/lkml/1545966002-3075-3-git-send-email-kernelfans@gmail.com/ > [2] https://lore.kernel.org/lkml/1545966002-3075-2-git-send-email-kernelfans@gmail.com/ > > > + > > + return ret; > > +} > > + > > /** > > * __memblock_find_range_top_down - find free area utility, in top-down > > * @start: start of candidate range > > -- > > 2.7.4 > > > > -- > Sincerely yours, > Mike. >