From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f198.google.com (mail-io0-f198.google.com [209.85.223.198]) by kanga.kvack.org (Postfix) with ESMTP id B2D9D6B060A for ; Thu, 3 Aug 2017 17:25:01 -0400 (EDT) Received: by mail-io0-f198.google.com with SMTP id z196so23843058ioe.3 for ; Thu, 03 Aug 2017 14:25:01 -0700 (PDT) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id u21si8822190ite.182.2017.08.03.14.24.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 Aug 2017 14:25:00 -0700 (PDT) From: Pavel Tatashin Subject: [v5 02/15] x86/mm: setting fields in deferred pages Date: Thu, 3 Aug 2017 17:23:40 -0400 Message-Id: <1501795433-982645-3-git-send-email-pasha.tatashin@oracle.com> In-Reply-To: <1501795433-982645-1-git-send-email-pasha.tatashin@oracle.com> References: <1501795433-982645-1-git-send-email-pasha.tatashin@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: 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, mhocko@kernel.org 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; 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 --- arch/x86/mm/init_64.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 136422d7d539..1e863baec847 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1165,12 +1165,17 @@ void __init mem_init(void) /* clear_bss() already clear the empty_zero_page */ - register_page_bootmem_info(); - /* this will put all memory onto the freelists */ free_all_bootmem(); after_bootmem = 1; + /* 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(); + /* Register memory areas for /proc/kcore */ kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE, KCORE_OTHER); -- 2.13.4 -- 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