From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + =?US-ASCII?Q?mm-memmap=5Finit-iterate-over-memblock-regions-rather-tha?= =?US-ASCII?Q?t-check-each-pfn-fix-2.patch?= added to -mm tree Date: Wed, 20 May 2020 19:39:48 -0700 Message-ID: <20200521023948.850WHlJkJ%akpm@linux-foundation.org> References: <20200513175005.1f4839360c18c0238df292d1@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Return-path: Received: from mail.kernel.org ([198.145.29.99]:54676 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727873AbgEUCju (ORCPT ); Wed, 20 May 2020 22:39:50 -0400 In-Reply-To: <20200513175005.1f4839360c18c0238df292d1@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: bhe@redhat.com, cai@lca.pw, hoan@os.amperecomputing.com, mm-commits@vger.kernel.org, rppt@linux.ibm.com, sfr@canb.auug.org.au The patch titled Subject: mm/compaction: fix the incorrect hole in fast_isolate_freepages() has been added to the -mm tree. Its filename is mm-memmap_init-iterate-over-memblock-regions-rather-that-check-each-pfn-fix-2.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-memmap_init-iterate-over-memblock-regions-rather-that-check-each-pfn-fix-2.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-memmap_init-iterate-over-memblock-regions-rather-that-check-each-pfn-fix-2.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Baoquan He Subject: mm/compaction: fix the incorrect hole in fast_isolate_freepages() Qian reported that a crash happened in compaction. http://lkml.kernel.org/r/8C537EB7-85EE-4DCF-943E-3CC0ED0DF56D@lca.pw LTP: starting swapping01 (swapping01 -i 5) page:ffffea0000aa0000 refcount:1 mapcount:0 mapping:000000002243743b index:0x0 flags: 0x1fffe000001000(reserved) raw: 001fffe000001000 ffffea0000aa0008 ffffea0000aa0008 0000000000000000 raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 page dumped because: VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn)) page_owner info is not present (never set?) ------------[ cut here ]------------ kernel BUG at mm/page_alloc.c:533! ... CPU: 17 PID: 218 Comm: kcompactd0 Not tainted 5.7.0-rc2-next-20200423+ #7 ... RIP: 0010:set_pfnblock_flags_mask+0x150/0x210 ... RSP: 0018:ffffc900042ff858 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff9a002382 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8884535b8e6c RBP: ffffc900042ff8b8 R08: ffffed108a6b8459 R09: ffffed108a6b8459 R10: ffff8884535c22c7 R11: ffffed108a6b8458 R12: 000000000002a800 R13: ffffea0000aa0000 R14: ffff88847fff3000 R15: ffff88847fff3040 FS: 0000000000000000(0000) GS:ffff888453580000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd1eb4a1000 CR3: 000000083154c000 CR4: 00000000003406e0 Call Trace: isolate_freepages+0xb20/0x1140 ? isolate_freepages_block+0x730/0x730 ? mark_held_locks+0x34/0xb0 ? free_unref_page+0x7d/0x90 ? free_unref_page+0x7d/0x90 ? check_flags.part.28+0x86/0x220 compaction_alloc+0xdd/0x100 migrate_pages+0x304/0x17e0 ? __ClearPageMovable+0x100/0x100 ? isolate_freepages+0x1140/0x1140 compact_zone+0x1249/0x1e90 ? compaction_suitable+0x260/0x260 kcompactd_do_work+0x231/0x650 ? sysfs_compact_node+0x80/0x80 ? finish_wait+0xe6/0x110 kcompactd+0x162/0x490 ? kcompactd_do_work+0x650/0x650 ? finish_wait+0x110/0x110 ? __kasan_check_read+0x11/0x20 ? __kthread_parkme+0xd4/0xf0 ? kcompactd_do_work+0x650/0x650 kthread+0x1f7/0x220 ? kthread_create_worker_on_cpu+0xc0/0xc0 ret_from_fork+0x27/0x50 After investigation, it turns out that this is introduced by commit of linux-next: commit f6edbdb71877 ("mm: memmap_init: iterate over memblock regions rather that check each PFN"). After investigation, it turns out that this is introduced by commit of linux-next, the patch subject is: "mm: memmap_init: iterate over memblock regions rather that check each PFN". Qian added debugging code. The debugging log shows that the fault page is 0x2a800000. From the system e820 map which is pasted at bottom, the page is in e820 reserved range: BIOS-e820: [mem 0x0000000029ffe000-0x000000002a80afff] reserved And it's in section [0x28000000, 0x2fffffff]. In that secion, there are several usable ranges and some e820 reserved ranges. For this kind of e820 reserved range, it won't be added to memblock allocator. However, init_unavailable_mem() will initialize to add them into node 0, zone 0. Before that commit, later, memmap_init() will add e820 reserved ranges into the zone where they are contained, because it can pass the checking of early_pfn_valid() and early_pfn_in_nid(). In this case, the e820 reserved range where fault page 0x2a800000 is located is added into DMA32 zone. After that commit, the e820 reserved rgions are kept in node 0, zone 0, since we iterate over memblock regions to iniatialize in memmap_init() instead, their node and zone won't be changed. Now, fast_isolate_freepages() will use min mark directly as the migration target if no page is found from buddy. However, the min mark is not checked carefully, it could be in e820 reserved range, and trigger the VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn)) when try to mark it as skip. Here, let's call pageblock_pfn_to_page() to get page of min_pfn, since it will do careful checks and return NULL if the pfn is not qualified. [ 0.000000] BIOS-provided physical RAM map: [ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000008bfff] usable [ 0.000000] BIOS-e820: [mem 0x000000000008c000-0x000000000009ffff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x0000000028328fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000028329000-0x0000000028568fff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000028569000-0x0000000028d85fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000028d86000-0x0000000028ee5fff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000028ee6000-0x0000000029a04fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000029a05000-0x0000000029a08fff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000029a09000-0x0000000029ee4fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000029ee5000-0x0000000029ef2fff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000029ef3000-0x0000000029f22fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000029f23000-0x0000000029f23fff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000029f24000-0x0000000029f24fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000029f25000-0x0000000029f28fff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000029f29000-0x0000000029f29fff] ACPI NVS [ 0.000000] BIOS-e820: [mem 0x0000000029f2a000-0x0000000029f2bfff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000029f2c000-0x0000000029f2cfff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000029f2d000-0x0000000029f2ffff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000029f30000-0x0000000029ffdfff] usable [ 0.000000] BIOS-e820: [mem 0x0000000029ffe000-0x000000002a80afff] reserved [ 0.000000] BIOS-e820: [mem 0x000000002a80b000-0x000000002a80efff] ACPI NVS [ 0.000000] BIOS-e820: [mem 0x000000002a80f000-0x000000002a81ffff] reserved [ 0.000000] BIOS-e820: [mem 0x000000002a820000-0x000000002a822fff] ACPI NVS [ 0.000000] BIOS-e820: [mem 0x000000002a823000-0x0000000033a22fff] usable [ 0.000000] BIOS-e820: [mem 0x0000000033a23000-0x0000000033a32fff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000033a33000-0x0000000033a42fff] ACPI NVS [ 0.000000] BIOS-e820: [mem 0x0000000033a43000-0x0000000033a52fff] ACPI data [ 0.000000] BIOS-e820: [mem 0x0000000033a53000-0x0000000077ffffff] usable [ 0.000000] BIOS-e820: [mem 0x0000000078000000-0x000000008fffffff] reserved [ 0.000000] BIOS-e820: [mem 0x00000000fed80000-0x00000000fed80fff] reserved [ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000087effffff] usable [ 0.000000] BIOS-e820: [mem 0x000000087f000000-0x000000087fffffff] reserved Link: http://lkml.kernel.org/r/20200521014407.29690-1-bhe@redhat.com Signed-off-by: Baoquan He Reported-by: Qian Cai Cc: Stephen Rothwell Cc: Mike Rapoport Cc: Hoan Tran Signed-off-by: Andrew Morton --- mm/compaction.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/compaction.c~mm-memmap_init-iterate-over-memblock-regions-rather-that-check-each-pfn-fix-2 +++ a/mm/compaction.c @@ -1418,7 +1418,9 @@ fast_isolate_freepages(struct compact_co cc->free_pfn = highest; } else { if (cc->direct_compaction && pfn_valid(min_pfn)) { - page = pfn_to_page(min_pfn); + page = pageblock_pfn_to_page(min_pfn, + pageblock_end_pfn(min_pfn), + cc->zone); cc->free_pfn = min_pfn; } } _ Patches currently in -mm which might be from bhe@redhat.com are maintainers-add-files-related-to-kdump.patch mm-memmap_init-iterate-over-memblock-regions-rather-that-check-each-pfn.patch mm-memmap_init-iterate-over-memblock-regions-rather-that-check-each-pfn-fix-2.patch mm-remove-unused-free_bootmem_with_active_regions.patch mm-page_allocc-only-tune-sysctl_lowmem_reserve_ratio-value-once-when-changing-it.patch mm-page_allocc-clear-out-zone-lowmem_reserve-if-the-zone-is-empty.patch mm-vmstatc-do-not-show-lowmem-reserve-protection-information-of-empty-zone.patch