On Tue, Feb 07, 2023 at 08:21:51AM +0000, Aaron Thompson wrote:
> This reverts commit 115d9d77bb0f9152c60b6e8646369fa7f6167593.
>
> The pages being freed by memblock_free_late() have already been
> initialized, but if they are in the deferred init range,
> __free_one_page() might access nearby uninitialized pages when trying to
> coalesce buddies. This can, for example, trigger this BUG:
>
> BUG: unable to handle page fault for address: ffffe964c02580c8
> RIP: 0010:__list_del_entry_valid+0x3f/0x70
> <TASK>
> __free_one_page+0x139/0x410
> __free_pages_ok+0x21d/0x450
> memblock_free_late+0x8c/0xb9
> efi_free_boot_services+0x16b/0x25c
> efi_enter_virtual_mode+0x403/0x446
> start_kernel+0x678/0x714
> secondary_startup_64_no_verify+0xd2/0xdb
> </TASK>
>
> A proper fix will be more involved so revert this change for the time
> being.
>
> Fixes: 115d9d77bb0f ("mm: Always release pages to the buddy allocator in memblock_free_late().")
> Signed-off-by: Aaron Thompson <dev@xxxxxxxxxx>
> ---
> mm/memblock.c | 8 +-------
> tools/testing/memblock/internal.h | 4 ----
> 2 files changed, 1 insertion(+), 11 deletions(-)
Applied, thanks!
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 685e30e6d27c..d036c7861310 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1640,13 +1640,7 @@ void __init memblock_free_late(phys_addr_t base, phys_addr_t size)
> end = PFN_DOWN(base + size);
>
> for (; cursor < end; cursor++) {
> - /*
> - * Reserved pages are always initialized by the end of
> - * memblock_free_all() (by memmap_init() and, if deferred
> - * initialization is enabled, memmap_init_reserved_pages()), so
> - * these pages can be released directly to the buddy allocator.
> - */
> - __free_pages_core(pfn_to_page(cursor), 0);
> + memblock_free_pages(pfn_to_page(cursor), cursor, 0);
> totalram_pages_inc();
> }
> }
> diff --git a/tools/testing/memblock/internal.h b/tools/testing/memblock/internal.h
> index 85973e55489e..fdb7f5db7308 100644
> --- a/tools/testing/memblock/internal.h
> +++ b/tools/testing/memblock/internal.h
> @@ -15,10 +15,6 @@ bool mirrored_kernelcore = false;
>
> struct page {};
>
> -void __free_pages_core(struct page *page, unsigned int order)
> -{
> -}
> -
> void memblock_free_pages(struct page *page, unsigned long pfn,
> unsigned int order)
> {
> --
> 2.30.2
>
>
--
Sincerely yours,
Mike.
