Commit 631ca890 authored by Philip Redkin's avatar Philip Redkin Committed by Ingo Molnar
Browse files

x86/mm: Check return value from memblock_phys_alloc_range() 



At least with CONFIG_PHYSICAL_START=0x100000, if there is < 4 MiB of
contiguous free memory available at this point, the kernel will crash
and burn because memblock_phys_alloc_range() returns 0 on failure,
which leads memblock_phys_free() to throw the first 4 MiB of physical
memory to the wolves.

At a minimum it should fail gracefully with a meaningful diagnostic,
but in fact everything seems to work fine without the weird reserve
allocation.

Signed-off-by: default avatarPhilip Redkin <me@rarity.fan>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/94b3e98f-96a7-3560-1f76-349eb95ccf7f@rarity.fan
parent 89771319

arch/x86/mm/init.c

+7 −2
Original line number Diff line number Diff line
@@ -645,8 +645,13 @@ static void __init memory_map_top_down(unsigned long map_start, 
	 */

	addr = memblock_phys_alloc_range(PMD_SIZE, PMD_SIZE, map_start,

					 map_end);

	if (!addr) {

		pr_warn("Failed to release memory for alloc_low_pages()");

		real_end = max(map_start, ALIGN_DOWN(map_end, PMD_SIZE));

	} else {

		memblock_phys_free(addr, PMD_SIZE);

		real_end = addr + PMD_SIZE;

	}



	/* step_size need to be small so pgt_buf from BRK could cover it */

	step_size = PMD_SIZE;