From: Wei Yang richardw.yang@linux.intel.com
commit 18e19f195cd888f65643a77a0c6aee8f5be6439a upstream.
When we use SPARSEMEM instead of SPARSEMEM_VMEMMAP, pfn_to_page() doesn't work before sparse_init_one_section() is called.
This leads to a crash when hotplug memory:
BUG: unable to handle page fault for address: 0000000006400000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP PTI CPU: 3 PID: 221 Comm: kworker/u16:1 Tainted: G W 5.5.0-next-20200205+ #343 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 Workqueue: kacpi_hotplug acpi_hotplug_work_fn RIP: 0010:__memset+0x24/0x30 Code: cc cc cc cc cc cc 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3 RSP: 0018:ffffb43ac0373c80 EFLAGS: 00010a87 RAX: ffffffffffffffff RBX: ffff8a1518800000 RCX: 0000000000050000 RDX: 0000000000000000 RSI: 00000000000000ff RDI: 0000000006400000 RBP: 0000000000140000 R08: 0000000000100000 R09: 0000000006400000 R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000 R13: 0000000000000028 R14: 0000000000000000 R15: ffff8a153ffd9280 FS: 0000000000000000(0000) GS:ffff8a153ab00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000006400000 CR3: 0000000136fca000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: sparse_add_section+0x1c9/0x26a __add_pages+0xbf/0x150 add_pages+0x12/0x60 add_memory_resource+0xc8/0x210 __add_memory+0x62/0xb0 acpi_memory_device_add+0x13f/0x300 acpi_bus_attach+0xf6/0x200 acpi_bus_scan+0x43/0x90 acpi_device_hotplug+0x275/0x3d0 acpi_hotplug_work_fn+0x1a/0x30 process_one_work+0x1a7/0x370 worker_thread+0x30/0x380 kthread+0x112/0x130 ret_from_fork+0x35/0x40
We should use memmap as it did.
On x86 the impact is limited to x86_32 builds, or x86_64 configurations that override the default setting for SPARSEMEM_VMEMMAP.
Other memory hotplug archs (arm64, ia64, and ppc) also default to SPARSEMEM_VMEMMAP=y.
[dan.j.williams@intel.com: changelog update] {rppt@linux.ibm.com: changelog update] Link: http://lkml.kernel.org/r/20200219030454.4844-1-bhe@redhat.com Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") Signed-off-by: Wei Yang richardw.yang@linux.intel.com Signed-off-by: Baoquan He bhe@redhat.com Acked-by: David Hildenbrand david@redhat.com Reviewed-by: Baoquan He bhe@redhat.com Reviewed-by: Dan Williams dan.j.williams@intel.com Acked-by: Michal Hocko mhocko@suse.com Cc: Mike Rapoport rppt@linux.ibm.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
--- mm/sparse.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/sparse.c +++ b/mm/sparse.c @@ -884,7 +884,7 @@ int __meminit sparse_add_section(int nid * Poison uninitialized struct pages in order to catch invalid flags * combinations. */ - page_init_poison(pfn_to_page(start_pfn), sizeof(struct page) * nr_pages); + page_init_poison(memmap, sizeof(struct page) * nr_pages);
ms = __nr_to_section(section_nr); set_section_nid(section_nr, nid);