This is a note to let you know that I've just added the patch titled Revert "mm: Always release pages to the buddy allocator in memblock_free_late()." to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: revert-mm-always-release-pages-to-the-buddy-allocator-in-memblock_free_late.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 647037adcad00f2bab8828d3d41cd0553d41f3bd Mon Sep 17 00:00:00 2001 From: Aaron Thompson <dev@xxxxxxxxxx> Date: Tue, 7 Feb 2023 08:21:51 +0000 Subject: Revert "mm: Always release pages to the buddy allocator in memblock_free_late()." From: Aaron Thompson <dev@xxxxxxxxxx> commit 647037adcad00f2bab8828d3d41cd0553d41f3bd upstream. 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> Link: https://lore.kernel.org/r/20230207082151.1303-1-dev@xxxxxxxxxx Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/memblock.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1615,13 +1615,7 @@ void __init __memblock_free_late(phys_ad 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(); } } Patches currently in stable-queue which might be from dev@xxxxxxxxxx are queue-5.15/revert-mm-always-release-pages-to-the-buddy-allocator-in-memblock_free_late.patch