Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit bfb9956a authored by Michael Ellerman's avatar Michael Ellerman
Browse files

powerpc/mm: Fix crash in page table dump with huge pages 



The page table dump code doesn't know about huge pages, so currently
it crashes (or walks random memory, usually leading to a crash), if it
finds a huge page. On Book3S we only see huge pages in the Linux page
tables when we're using the P9 Radix MMU.

Teaching the code to properly handle huge pages is a bit more involved,
so for now just prevent the crash.

Cc: stable@vger.kernel.org # v4.10+
Fixes: 8eb07b18 ("powerpc/mm: Dump linux pagetables")
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent d04c02f8

arch/powerpc/mm/dump_linuxpagetables.c

+4 −3
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
 */

#include <linux/debugfs.h>

#include <linux/fs.h>

#include <linux/hugetlb.h>

#include <linux/io.h>

#include <linux/mm.h>

#include <linux/sched.h>
@@ -391,7 +392,7 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) 


	for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {

		addr = start + i * PMD_SIZE;

		if (!pmd_none(*pmd))

		if (!pmd_none(*pmd) && !pmd_huge(*pmd))

			/* pmd exists */

			walk_pte(st, pmd, addr);

		else
@@ -407,7 +408,7 @@ static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start) 


	for (i = 0; i < PTRS_PER_PUD; i++, pud++) {

		addr = start + i * PUD_SIZE;

		if (!pud_none(*pud))

		if (!pud_none(*pud) && !pud_huge(*pud))

			/* pud exists */

			walk_pmd(st, pud, addr);

		else
@@ -427,7 +428,7 @@ static void walk_pagetables(struct pg_state *st) 
	 */

	for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {

		addr = KERN_VIRT_START + i * PGDIR_SIZE;

		if (!pgd_none(*pgd))

		if (!pgd_none(*pgd) && !pgd_huge(*pgd))

			/* pgd exists */

			walk_pud(st, pgd, addr);

		else