mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page()

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