From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752008AbdH3BJb (ORCPT ); Tue, 29 Aug 2017 21:09:31 -0400 Received: from shards.monkeyblade.net ([184.105.139.130]:43064 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751794AbdH3BJ3 (ORCPT ); Tue, 29 Aug 2017 21:09:29 -0400 Date: Tue, 29 Aug 2017 18:09:28 -0700 (PDT) Message-Id: <20170829.180928.896986367806428362.davem@davemloft.net> To: pasha.tatashin@oracle.com 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, willy@infradead.org, mhocko@kernel.org, ard.biesheuvel@linaro.org, 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 Subject: Re: [PATCH v7 02/11] sparc64/mm: setting fields in deferred pages From: David Miller In-Reply-To: <1503972142-289376-3-git-send-email-pasha.tatashin@oracle.com> References: <1503972142-289376-1-git-send-email-pasha.tatashin@oracle.com> <1503972142-289376-3-git-send-email-pasha.tatashin@oracle.com> X-Mailer: Mew version 6.7 on Emacs 25.2 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Tue, 29 Aug 2017 18:09:29 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Tatashin Date: Mon, 28 Aug 2017 22:02:13 -0400 > 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