From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 188ED6B0038 for ; Tue, 3 Oct 2017 08:28:26 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id q203so5473104wmb.0 for ; Tue, 03 Oct 2017 05:28:26 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id p3si5695154wrc.519.2017.10.03.05.28.24 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 03 Oct 2017 05:28:24 -0700 (PDT) Date: Tue, 3 Oct 2017 14:28:23 +0200 From: Michal Hocko Subject: Re: [PATCH v9 02/12] sparc64/mm: setting fields in deferred pages Message-ID: <20171003122823.mdzkhxs4xza7sb2w@dhcp22.suse.cz> References: <20170920201714.19817-1-pasha.tatashin@oracle.com> <20170920201714.19817-3-pasha.tatashin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170920201714.19817-3-pasha.tatashin@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Pavel Tatashin Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, kasan-dev@googlegroups.com, borntraeger@de.ibm.com, heiko.carstens@de.ibm.com, davem@davemloft.net, willy@infradead.org, ard.biesheuvel@linaro.org, mark.rutland@arm.com, will.deacon@arm.com, catalin.marinas@arm.com, sam@ravnborg.org, mgorman@techsingularity.net, steven.sistare@oracle.com, daniel.m.jordan@oracle.com, bob.picco@oracle.com On Wed 20-09-17 16:17:04, Pavel Tatashin wrote: > Without deferred struct page feature (CONFIG_DEFERRED_STRUCT_PAGE_INIT), > flags and other fields in "struct page"es are never changed prior to first > initializing struct pages by going through __init_single_page(). > > With deferred struct page feature enabled there is a case where we set some > fields prior to initializing: > > mem_init() { > register_page_bootmem_info(); > free_all_bootmem(); > ... > } > > When register_page_bootmem_info() is called only non-deferred struct pages > are initialized. But, this function goes through some reserved pages which > might be part of the deferred, and thus are not yet initialized. > > mem_init > register_page_bootmem_info > register_page_bootmem_info_node > get_page_bootmem > .. setting fields here .. > such as: page->freelist = (void *)type; > > free_all_bootmem() > free_low_memory_core_early() > for_each_reserved_mem_region() > reserve_bootmem_region() > init_reserved_page() <- Only if this is deferred reserved page > __init_single_pfn() > __init_single_page() > memset(0) <-- Loose the set fields here > > We end-up with similar issue as in the previous patch, where currently we > do not observe problem as memory is zeroed. But, if flag asserts are > changed we can start hitting issues. > > Also, because in this patch series we will stop zeroing struct page memory > during allocation, we must make sure that struct pages are properly > initialized prior to using them. > > The deferred-reserved pages are initialized in free_all_bootmem(). > Therefore, the fix is to switch the above calls. > > Signed-off-by: Pavel Tatashin > Reviewed-by: Steven Sistare > Reviewed-by: Daniel Jordan > Reviewed-by: Bob Picco > Acked-by: David S. Miller As you separated x86 and sparc patches doing essentially the same I assume David is going to take this patch? Acked-by: Michal Hocko > --- > arch/sparc/mm/init_64.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c > index 6034569e2c0d..310c6754bcaa 100644 > --- a/arch/sparc/mm/init_64.c > +++ b/arch/sparc/mm/init_64.c > @@ -2548,9 +2548,15 @@ void __init mem_init(void) > { > high_memory = __va(last_valid_pfn << PAGE_SHIFT); > > - register_page_bootmem_info(); > free_all_bootmem(); > > + /* Must be done after boot memory is put on freelist, because here we > + * might set fields in deferred struct pages that have not yet been > + * initialized, and free_all_bootmem() initializes all the reserved > + * deferred pages for us. > + */ > + register_page_bootmem_info(); > + > /* > * Set up the zero page, mark it reserved, so that page count > * is not manipulated when freeing the page from user ptes. > -- > 2.14.1 -- Michal Hocko SUSE Labs -- 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