From patchwork Tue Feb 11 00:15:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11374321 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 22A5B139A for ; Tue, 11 Feb 2020 00:16:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 036FB20838 for ; Tue, 11 Feb 2020 00:16:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="b15JXq87" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727821AbgBKAQK (ORCPT ); Mon, 10 Feb 2020 19:16:10 -0500 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:4287 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727683AbgBKAPm (ORCPT ); Mon, 10 Feb 2020 19:15:42 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 10 Feb 2020 16:14:36 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 10 Feb 2020 16:15:39 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 10 Feb 2020 16:15:39 -0800 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 11 Feb 2020 00:15:38 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 11 Feb 2020 00:15:38 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Mon, 10 Feb 2020 16:15:38 -0800 From: John Hubbard To: Andrew Morton CC: Al Viro , Christoph Hellwig , Dan Williams , Dave Chinner , Ira Weiny , Jan Kara , Jason Gunthorpe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , "Kirill A . Shutemov" , Michal Hocko , Mike Kravetz , Shuah Khan , Vlastimil Babka , Matthew Wilcox , , , , , , LKML , John Hubbard , "Kirill A . Shutemov" Subject: [PATCH v6 11/12] mm: Improve dump_page() for compound pages Date: Mon, 10 Feb 2020 16:15:35 -0800 Message-ID: <20200211001536.1027652-12-jhubbard@nvidia.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200211001536.1027652-1-jhubbard@nvidia.com> References: <20200211001536.1027652-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1581380076; bh=OEd2wPZ0nio0/lMg6Wc3iY7JuP/KkGjSqYpxktig1Bk=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=b15JXq87UAwu5VDwVtaVlAZHpsbrY71cOtbd87znRSNsi+QhDasuq+HujoeSnOHil sSJtrrq5xr1FhdJtwuTQBJkyOew05X2gqH8Q4FinkFhlZLS+j7Re2uBprDM6UTFy9C UuKvN2twgVHCBUXeaEDMg5kKmnj7tm6zznf5uTMTir7KdJf1ynO4MozSrzYrDDvoGn qxpyFpXsIINwbk4VYAhIuMRpAx27V8jZkC/114TCHUZo/SJVzsU2bMMW9uwxUs9Afy ihfXORlYfsw9/mPfhSM9oBxpxvEXlawNsmlqi6J7gTxIUe/JZWI4U7+nT7q7y38awr nxBU8rmxhMKqg== Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org From: "Matthew Wilcox (Oracle)" There was no protection against a corrupted struct page having an implausible compound_head(). Sanity check that a compound page has a head within reach of the maximum allocatable page (this will need to be adjusted if one of the plans to allocate 1GB pages comes to fruition). In addition, - Print the mapping pointer using %p insted of %px. The actual value of the pointer can be read out of the raw page dump and using %p gives a chance to correlate it with an earlier printk of the mapping pointer - Print the mapping pointer from the head page, not the tail page (the tail ->mapping pointer may be in use for other purposes, eg part of a list_head) - Print the order of the page for compound pages - Dump the raw head page as well as the raw page - Print the refcount from the head page, not the tail page Suggested-by: Kirill A. Shutemov Co-developed-by: John Hubbard Signed-off-by: John Hubbard Signed-off-by: Matthew Wilcox (Oracle) --- mm/debug.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/mm/debug.c b/mm/debug.c index ecccd9f17801..f5ffb0784559 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -44,8 +44,10 @@ const struct trace_print_flags vmaflag_names[] = { void __dump_page(struct page *page, const char *reason) { + struct page *head = compound_head(page); struct address_space *mapping; bool page_poisoned = PagePoisoned(page); + bool compound = PageCompound(page); /* * Accessing the pageblock without the zone lock. It could change to * "isolate" again in the meantime, but since we are just dumping the @@ -66,25 +68,32 @@ void __dump_page(struct page *page, const char *reason) goto hex_only; } - mapping = page_mapping(page); + if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) { + /* Corrupt page, cannot call page_mapping */ + mapping = page->mapping; + head = page; + compound = false; + } else { + mapping = page_mapping(page); + } /* * Avoid VM_BUG_ON() in page_mapcount(). * page->_mapcount space in struct page is used by sl[aou]b pages to * encode own info. */ - mapcount = PageSlab(page) ? 0 : page_mapcount(page); + mapcount = PageSlab(head) ? 0 : page_mapcount(page); - if (PageCompound(page)) - pr_warn("page:%px refcount:%d mapcount:%d mapping:%px " - "index:%#lx compound_mapcount: %d\n", - page, page_ref_count(page), mapcount, - page->mapping, page_to_pgoff(page), - compound_mapcount(page)); + if (compound) + pr_warn("page:%px refcount:%d mapcount:%d mapping:%p " + "index:%#lx head:%px order:%u compound_mapcount:%d\n", + page, page_ref_count(head), mapcount, + mapping, page_to_pgoff(page), head, + compound_order(head), compound_mapcount(page)); else - pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n", + pr_warn("page:%px refcount:%d mapcount:%d mapping:%p index:%#lx\n", page, page_ref_count(page), mapcount, - page->mapping, page_to_pgoff(page)); + mapping, page_to_pgoff(page)); if (PageKsm(page)) type = "ksm "; else if (PageAnon(page)) @@ -106,6 +115,10 @@ void __dump_page(struct page *page, const char *reason) print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, sizeof(unsigned long), page, sizeof(struct page), false); + if (head != page) + print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32, + sizeof(unsigned long), head, + sizeof(struct page), false); if (reason) pr_warn("page dumped because: %s\n", reason);