https://github.com/torvalds/linux
Revision 3366cdb6d350d95466ee430ac50f3c8415ca8f46 authored by Olaf Hering on 07 September 2018, 14:31:35 UTC, committed by Boris Ostrovsky on 14 September 2018, 12:51:10 UTC
The command 'xl vcpu-set 0 0', issued in dom0, will crash dom0: BUG: unable to handle kernel NULL pointer dereference at 00000000000002d8 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 65 Comm: xenwatch Not tainted 4.19.0-rc2-1.ga9462db-default #1 openSUSE Tumbleweed (unreleased) Hardware name: Intel Corporation S5520UR/S5520UR, BIOS S5500.86B.01.00.0050.050620101605 05/06/2010 RIP: e030:device_offline+0x9/0xb0 Code: 77 24 00 e9 ce fe ff ff 48 8b 13 e9 68 ff ff ff 48 8b 13 e9 29 ff ff ff 48 8b 13 e9 ea fe ff ff 90 66 66 66 66 90 41 54 55 53 <f6> 87 d8 02 00 00 01 0f 85 88 00 00 00 48 c7 c2 20 09 60 81 31 f6 RSP: e02b:ffffc90040f27e80 EFLAGS: 00010203 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff8801f3800000 RSI: ffffc90040f27e70 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffffff820e47b3 R09: 0000000000000000 R10: 0000000000007ff0 R11: 0000000000000000 R12: ffffffff822e6d30 R13: dead000000000200 R14: dead000000000100 R15: ffffffff8158b4e0 FS: 00007ffa595158c0(0000) GS:ffff8801f39c0000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000002d8 CR3: 00000001d9602000 CR4: 0000000000002660 Call Trace: handle_vcpu_hotplug_event+0xb5/0xc0 xenwatch_thread+0x80/0x140 ? wait_woken+0x80/0x80 kthread+0x112/0x130 ? kthread_create_worker_on_cpu+0x40/0x40 ret_from_fork+0x3a/0x50 This happens because handle_vcpu_hotplug_event is called twice. In the first iteration cpu_present is still true, in the second iteration cpu_present is false which causes get_cpu_device to return NULL. In case of cpu#0, cpu_online is apparently always true. Fix this crash by checking if the cpu can be hotplugged, which is false for a cpu that was just removed. Also check if the cpu was actually offlined by device_remove, otherwise leave the cpu_present state as it is. Rearrange to code to do all work with device_hotplug_lock held. Signed-off-by: Olaf Hering <olaf@aepfle.de> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
1 parent 197ecb3
Tip revision: 3366cdb6d350d95466ee430ac50f3c8415ca8f46 authored by Olaf Hering on 07 September 2018, 14:31:35 UTC
xen: avoid crash in disable_hotplug_cpu
xen: avoid crash in disable_hotplug_cpu
Tip revision: 3366cdb
| File | Mode | Size |
|---|---|---|
| kasan | ||
| Kconfig | -rw-r--r-- | 24.7 KB |
| Kconfig.debug | -rw-r--r-- | 3.8 KB |
| Makefile | -rw-r--r-- | 3.6 KB |
| backing-dev.c | -rw-r--r-- | 26.9 KB |
| balloon_compaction.c | -rw-r--r-- | 5.5 KB |
| bootmem.c | -rw-r--r-- | 19.8 KB |
| cleancache.c | -rw-r--r-- | 9.9 KB |
| cma.c | -rw-r--r-- | 13.9 KB |
| cma.h | -rw-r--r-- | 573 bytes |
| cma_debug.c | -rw-r--r-- | 4.5 KB |
| compaction.c | -rw-r--r-- | 58.7 KB |
| debug.c | -rw-r--r-- | 4.5 KB |
| debug_page_ref.c | -rw-r--r-- | 1.4 KB |
| dmapool.c | -rw-r--r-- | 13.7 KB |
| early_ioremap.c | -rw-r--r-- | 6.8 KB |
| fadvise.c | -rw-r--r-- | 5.0 KB |
| failslab.c | -rw-r--r-- | 1.4 KB |
| filemap.c | -rw-r--r-- | 89.3 KB |
| frame_vector.c | -rw-r--r-- | 6.4 KB |
| frontswap.c | -rw-r--r-- | 14.2 KB |
| gup.c | -rw-r--r-- | 50.6 KB |
| gup_benchmark.c | -rw-r--r-- | 2.1 KB |
| highmem.c | -rw-r--r-- | 11.7 KB |
| hmm.c | -rw-r--r-- | 37.9 KB |
| huge_memory.c | -rw-r--r-- | 81.0 KB |
| hugetlb.c | -rw-r--r-- | 130.1 KB |
| hugetlb_cgroup.c | -rw-r--r-- | 10.9 KB |
| hwpoison-inject.c | -rw-r--r-- | 3.2 KB |
| init-mm.c | -rw-r--r-- | 1.2 KB |
| internal.h | -rw-r--r-- | 16.4 KB |
| interval_tree.c | -rw-r--r-- | 3.1 KB |
| khugepaged.c | -rw-r--r-- | 48.9 KB |
| kmemleak-test.c | -rw-r--r-- | 3.2 KB |
| kmemleak.c | -rw-r--r-- | 59.0 KB |
| ksm.c | -rw-r--r-- | 88.2 KB |
| list_lru.c | -rw-r--r-- | 14.6 KB |
| maccess.c | -rw-r--r-- | 3.1 KB |
| madvise.c | -rw-r--r-- | 22.8 KB |
| memblock.c | -rw-r--r-- | 54.5 KB |
| memcontrol.c | -rw-r--r-- | 170.2 KB |
| memfd.c | -rw-r--r-- | 8.4 KB |
| memory-failure.c | -rw-r--r-- | 52.1 KB |
| memory.c | -rw-r--r-- | 128.0 KB |
| memory_hotplug.c | -rw-r--r-- | 49.1 KB |
| mempolicy.c | -rw-r--r-- | 71.4 KB |
| mempool.c | -rw-r--r-- | 15.5 KB |
| memtest.c | -rw-r--r-- | 2.8 KB |
| migrate.c | -rw-r--r-- | 77.8 KB |
| mincore.c | -rw-r--r-- | 6.7 KB |
| mlock.c | -rw-r--r-- | 22.6 KB |
| mm_init.c | -rw-r--r-- | 4.8 KB |
| mmap.c | -rw-r--r-- | 98.9 KB |
| mmu_context.c | -rw-r--r-- | 1.3 KB |
| mmu_notifier.c | -rw-r--r-- | 12.4 KB |
| mmzone.c | -rw-r--r-- | 2.4 KB |
| mprotect.c | -rw-r--r-- | 15.6 KB |
| mremap.c | -rw-r--r-- | 17.0 KB |
| msync.c | -rw-r--r-- | 2.6 KB |
| nobootmem.c | -rw-r--r-- | 10.9 KB |
| nommu.c | -rw-r--r-- | 47.6 KB |
| oom_kill.c | -rw-r--r-- | 30.6 KB |
| page-writeback.c | -rw-r--r-- | 84.3 KB |
| page_alloc.c | -rw-r--r-- | 222.3 KB |
| page_counter.c | -rw-r--r-- | 6.6 KB |
| page_ext.c | -rw-r--r-- | 11.1 KB |
| page_idle.c | -rw-r--r-- | 5.5 KB |
| page_io.c | -rw-r--r-- | 10.5 KB |
| page_isolation.c | -rw-r--r-- | 8.7 KB |
| page_owner.c | -rw-r--r-- | 15.1 KB |
| page_poison.c | -rw-r--r-- | 2.7 KB |
| page_vma_mapped.c | -rw-r--r-- | 6.9 KB |
| pagewalk.c | -rw-r--r-- | 8.7 KB |
| percpu-internal.h | -rw-r--r-- | 5.9 KB |
| percpu-km.c | -rw-r--r-- | 2.9 KB |
| percpu-stats.c | -rw-r--r-- | 5.7 KB |
| percpu-vm.c | -rw-r--r-- | 10.3 KB |
| percpu.c | -rw-r--r-- | 84.5 KB |
| pgtable-generic.c | -rw-r--r-- | 5.3 KB |
| process_vm_access.c | -rw-r--r-- | 10.0 KB |
| quicklist.c | -rw-r--r-- | 2.4 KB |
| readahead.c | -rw-r--r-- | 16.8 KB |
| rmap.c | -rw-r--r-- | 53.1 KB |
| rodata_test.c | -rw-r--r-- | 1.4 KB |
| shmem.c | -rw-r--r-- | 104.4 KB |
| slab.c | -rw-r--r-- | 110.8 KB |
| slab.h | -rw-r--r-- | 14.6 KB |
| slab_common.c | -rw-r--r-- | 37.5 KB |
| slob.c | -rw-r--r-- | 16.2 KB |
| slub.c | -rw-r--r-- | 141.3 KB |
| sparse-vmemmap.c | -rw-r--r-- | 6.6 KB |
| sparse.c | -rw-r--r-- | 20.5 KB |
| swap.c | -rw-r--r-- | 28.7 KB |
| swap_cgroup.c | -rw-r--r-- | 5.2 KB |
| swap_slots.c | -rw-r--r-- | 9.4 KB |
| swap_state.c | -rw-r--r-- | 22.4 KB |
| swapfile.c | -rw-r--r-- | 95.7 KB |
| truncate.c | -rw-r--r-- | 26.4 KB |
| usercopy.c | -rw-r--r-- | 9.4 KB |
| userfaultfd.c | -rw-r--r-- | 15.0 KB |
| util.c | -rw-r--r-- | 19.7 KB |
| vmacache.c | -rw-r--r-- | 3.7 KB |
| vmalloc.c | -rw-r--r-- | 69.6 KB |
| vmpressure.c | -rw-r--r-- | 13.9 KB |
| vmscan.c | -rw-r--r-- | 119.9 KB |
| vmstat.c | -rw-r--r-- | 51.6 KB |
| workingset.c | -rw-r--r-- | 18.0 KB |
| z3fold.c | -rw-r--r-- | 30.0 KB |
| zbud.c | -rw-r--r-- | 18.2 KB |
| zpool.c | -rw-r--r-- | 10.7 KB |
| zsmalloc.c | -rw-r--r-- | 60.4 KB |
| zswap.c | -rw-r--r-- | 34.7 KB |
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