a74bb0eeab
commit ddbc84f3f595cf1fc8234a191193b5d20ad43938 upstream. ZONE_MOVABLE uses the remaining memory in each node. Its starting pfn is also aligned to MAX_ORDER_NR_PAGES. It is possible for the remaining memory in a node to be less than MAX_ORDER_NR_PAGES, meaning there is not enough room for ZONE_MOVABLE on that node. Unfortunately this condition is not checked for. This leads to zone_movable_pfn[] getting set to a pfn greater than the last pfn in a node. calculate_node_totalpages() then sets zone->present_pages to be greater than zone->spanned_pages which is invalid, as spanned_pages represents the maximum number of pages in a zone assuming no holes. Subsequently it is possible free_area_init_core() will observe a zone of size zero with present pages. In this case it will skip setting up the zone, including the initialisation of free_lists[]. However populated_zone() checks zone->present_pages to see if a zone has memory available. This is used by iterators such as walk_zones_in_node(). pagetypeinfo_showfree() uses this to walk the free_list of each zone in each node, which are assumed to be initialised due to the zone not being empty. As free_area_init_core() never initialised the free_lists[] this results in the following kernel crash when trying to read /proc/pagetypeinfo: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI CPU: 0 PID: 456 Comm: cat Not tainted 5.16.0 #461 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:pagetypeinfo_show+0x163/0x460 Code: 9e 82 e8 80 57 0e 00 49 8b 06 b9 01 00 00 00 4c 39 f0 75 16 e9 65 02 00 00 48 83 c1 01 48 81 f9 a0 86 01 00 0f 84 48 02 00 00 <48> 8b 00 4c 39 f0 75 e7 48 c7 c2 80 a2 e2 82 48 c7 c6 79 ef e3 82 RSP: 0018:ffffc90001c4bd10 EFLAGS: 00010003 RAX: 0000000000000000 RBX: ffff88801105f638 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 000000000000068b RDI: ffff8880163dc68b RBP: ffffc90001c4bd90 R08: 0000000000000001 R09: ffff8880163dc67e R10: 656c6261766f6d6e R11: 6c6261766f6d6e55 R12: ffff88807ffb4a00 R13: ffff88807ffb49f8 R14: ffff88807ffb4580 R15: ffff88807ffb3000 FS: 00007f9c83eff5c0(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000013c8e000 CR4: 0000000000350ef0 Call Trace: seq_read_iter+0x128/0x460 proc_reg_read_iter+0x51/0x80 new_sync_read+0x113/0x1a0 vfs_read+0x136/0x1d0 ksys_read+0x70/0xf0 __x64_sys_read+0x1a/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fix this by checking that the aligned zone_movable_pfn[] does not exceed the end of the node, and if it does skip creating a movable zone on this node. Link: https://lkml.kernel.org/r/20220215025831.2113067-1-apopple@nvidia.com Fixes: 2a1e274acf0b ("Create the ZONE_MOVABLE zone") Signed-off-by: Alistair Popple <apopple@nvidia.com> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.