CVE-2021-47090

In the Linux kernel, the following vulnerability has been resolved:
mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page() Hulk
Robot reported a panic in put_page_testzero() when testing madvise() with
MADV_SOFT_OFFLINE. The BUG() is triggered when retrying get_any_page().
This is because we keep MF_COUNT_INCREASED flag in second try but the
refcnt is not increased. page dumped because:
VM_BUG_ON_PAGE(page_ref_count(page) == 0) ------------[ cut here
]------------ kernel BUG at include/linux/mm.h:737! invalid opcode: 0000
[#1] PREEMPT SMP CPU: 5 PID: 2135 Comm: sshd Tainted: G B 5.16.0-rc6-dirty
#373 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014 RIP: release_pages+0x53f/0x840 Call Trace:
free_pages_and_swap_cache+0x64/0x80 tlb_flush_mmu+0x6f/0x220
unmap_page_range+0xe6c/0x12c0 unmap_single_vma+0x90/0x170
unmap_vmas+0xc4/0x180 exit_mmap+0xde/0x3a0 mmput+0xa3/0x250
do_exit+0x564/0x1470 do_group_exit+0x3b/0x100 __do_sys_exit_group+0x13/0x20
__x64_sys_exit_group+0x16/0x20 do_syscall_64+0x34/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae Modules linked in: —[ end trace
e99579b570fe0649 ]— RIP: 0010:release_pages+0x53f/0x840