From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2878775-1520035985-2-10706085317276082782 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no ("Email failed DMARC policy for domain") X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.249, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='com', MailFrom='org' X-Spam-charsets: X-IgnoreVacation: yes ("Email failed DMARC policy for domain") X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1520035984; b=Lt+qEj/YQDuYORrNz+sLdiDPAbrqyIoA7LpZEwVElBy/vGE YWKgx2C/IfOD9shl5oHH1mmFWi3mSNgyY2octINusRDyO1DOcCsILzp6oE7E1iSm rkKIBskl1FE1DjwjAN+SbKvto0lhWKULJ3G2l+ucAwWM8q5RkSZuYA7FbLx90H5W f/NNJPd1mn3Ca/phDx/a45D5YMHkJErkIt5+ppJHFLPfxBjG0tVnuVPqz8YCVrLu ejnPlCUVXuhoK4VKs8hn9URG4xGtzdrnfu6oLrGe9oKnisVu8pX0ouil5NGiniwv e5WxZwBEUsn/fQoMHhzHcaNmXZQAOP+a1I5JfIQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:in-reply-to:references:sender:list-id; s=arctest; t=1520035984; bh=xB6pRsgRc49+EjPMij0auvk8rq69Pbju5U5 h5a8R76k=; b=QpIRzz6EHrjLwc0OD6HRaCMVlwSHSkcjr7t0uH042C6WHa49R7P 3Z2a5XjcH2a3YdmEltrJqbMnLR1TVng3cYOOWEb06sKirDRS/2dMsvEBDjQ379cY L2Zc2N1fv8jvdcWHeNUCeiipVycP1VdCP1/aw0Vb8sqWjpOJ5wp+IDXxuLW/TLZI +s7lNspebKa/7siuJyhrCNiH0pQqlRpTYMIEzmnzGALU5ULEXZdUxcceS2K/lRni 7glzfQBSrLDFl0WA9iMQ4ThRMZchqCLWZiGD9rHFA5BOA1Ycqc48VIt/RGDogQag s7yMR8znIyoxrvUtAUgxsyA30pXwBs8TWYg== ARC-Authentication-Results: i=1; mx4.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Authentication-Results: mx4.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=fail (p=none,has-list-id=yes,d=none) header.from=redhat.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=redhat.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935272AbeCCAMv (ORCPT ); Fri, 2 Mar 2018 19:12:51 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:60916 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S935239AbeCCAMt (ORCPT ); Fri, 2 Mar 2018 19:12:49 -0500 From: Daniel Vacek To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Mel Gorman , Pavel Tatashin , Paul Burton , Daniel Vacek , stable@vger.kernel.org Subject: [PATCH v3 2/2] mm/page_alloc: fix memmap_init_zone pageblock alignment Date: Sat, 3 Mar 2018 01:12:26 +0100 Message-Id: <0485727b2e82da7efbce5f6ba42524b429d0391a.1520011945.git.neelx@redhat.com> In-Reply-To: References: <1519908465-12328-1-git-send-email-neelx@redhat.com> In-Reply-To: References: Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible") introduced a bug where move_freepages() triggers a VM_BUG_ON() on uninitialized page structure due to pageblock alignment. To fix this, simply align the skipped pfns in memmap_init_zone() the same way as in move_freepages_block(). >>From one of the RHEL reports: crash> log | grep -e BUG -e RIP -e Call.Trace -e move_freepages_block -e rmqueue -e freelist -A1 kernel BUG at mm/page_alloc.c:1389! invalid opcode: 0000 [#1] SMP -- RIP: 0010:[] [] move_freepages+0x15e/0x160 RSP: 0018:ffff88054d727688 EFLAGS: 00010087 -- Call Trace: [] move_freepages_block+0x73/0x80 [] __rmqueue+0x263/0x460 [] get_page_from_freelist+0x7e1/0x9e0 [] __alloc_pages_nodemask+0x176/0x420 -- RIP [] move_freepages+0x15e/0x160 RSP crash> page_init_bug -v | grep RAM 1000 - 9bfff System RAM (620.00 KiB) 100000 - 430bffff System RAM ( 1.05 GiB = 1071.75 MiB = 1097472.00 KiB) 4b0c8000 - 4bf9cfff System RAM ( 14.83 MiB = 15188.00 KiB) 4bfac000 - 646b1fff System RAM (391.02 MiB = 400408.00 KiB) 7b788000 - 7b7fffff System RAM (480.00 KiB) 100000000 - 67fffffff System RAM ( 22.00 GiB) crash> page_init_bug | head -6 7b788000 - 7b7fffff System RAM (480.00 KiB) 1fffff00000000 0 1 DMA32 4096 1048575 505736 505344 505855 0 0 0 DMA 1 4095 1fffff00000400 0 1 DMA32 4096 1048575 BUG, zones differ! Note that this range follows two not populated sections 68000000-77ffffff in this zone. 7b788000-7b7fffff is the first one after a gap. This makes memmap_init_zone() skip all the pfns up to the beginning of this range. But this range is not pageblock (2M) aligned. In fact no range has to be. crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b787000 7b788000 PAGE PHYSICAL MAPPING INDEX CNT FLAGS ffffea0001e00000 78000000 0 0 0 0 ffffea0001ed7fc0 7b5ff000 0 0 0 0 ffffea0001ed8000 7b600000 0 0 0 0 <<<< ffffea0001ede1c0 7b787000 0 0 0 0 ffffea0001ede200 7b788000 0 0 1 1fffff00000000 Top part of page flags should contain nodeid and zonenr, which is not the case for page ffffea0001ed8000 here (<<<<). crash> log | grep -o fffea0001ed[^\ ]* | sort -u fffea0001ed8000 fffea0001eded20 fffea0001edffc0 crash> bt -r | grep -o fffea0001ed[^\ ]* | sort -u fffea0001ed8000 fffea0001eded00 fffea0001eded20 fffea0001edffc0 Initialization of the whole beginning of the section is skipped up to the start of the range due to the commit b92df1de5d28. Now any code calling move_freepages_block() (like reusing the page from a freelist as in this example) with a page from the beginning of the range will get the page rounded down to start_page ffffea0001ed8000 and passed to move_freepages() which crashes on assertion getting wrong zonenr. > VM_BUG_ON(page_zone(start_page) != page_zone(end_page)); Note, page_zone() derives the zone from page flags here. >>From similar machine before commit b92df1de5d28: crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b7fe000 7b7ff000 PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffff73941e00000 78000000 0 0 1 1fffff00000000 fffff73941ed7fc0 7b5ff000 0 0 1 1fffff00000000 fffff73941ed8000 7b600000 0 0 1 1fffff00000000 fffff73941edff80 7b7fe000 0 0 1 1fffff00000000 fffff73941edffc0 7b7ff000 ffff8e67e04d3ae0 ad84 1 1fffff00020068 uptodate,lru,active,mappedtodisk All the pages since the beginning of the section are initialized. move_freepages()' not gonna blow up. The same machine with this fix applied: crash> kmem -p 77fff000 78000000 7b5ff000 7b600000 7b7fe000 7b7ff000 PAGE PHYSICAL MAPPING INDEX CNT FLAGS ffffea0001e00000 78000000 0 0 0 0 ffffea0001e00000 7b5ff000 0 0 0 0 ffffea0001ed8000 7b600000 0 0 1 1fffff00000000 ffffea0001edff80 7b7fe000 0 0 1 1fffff00000000 ffffea0001edffc0 7b7ff000 ffff88017fb13720 8 2 1fffff00020068 uptodate,lru,active,mappedtodisk At least the bare minimum of pages is initialized preventing the crash as well. Fixes: b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns where possible") Signed-off-by: Daniel Vacek Cc: stable@vger.kernel.org --- mm/page_alloc.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f2c57da5bbe5..eb27ccb50928 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5359,9 +5359,14 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, /* * Skip to the pfn preceding the next valid one (or * end_pfn), such that we hit a valid pfn (or end_pfn) - * on our next iteration of the loop. + * on our next iteration of the loop. Note that it needs + * to be pageblock aligned even when the region itself + * is not. move_freepages_block() can shift ahead of + * the valid region but still depends on correct page + * metadata. */ - pfn = memblock_next_valid_pfn(pfn) - 1; + pfn = (memblock_next_valid_pfn(pfn) & + ~(pageblock_nr_pages-1)) - 1; #endif continue; } -- 2.16.2