s390/mm,ptdump: hold cpa mutex while walking for kernel page table dump (da1694ad) · Commits · 戴 / test

This is currently only preventing that outdated information is provided to user space. A concurrent split of huge/large pages does modify the kernel page tables, however either the huge/large mapping is reported or the split area is being walked. This "fixes" also only a potential future bug, since split pages could also be merged again if page permissions are the same for larger memory areas. Reviewed-by:

Vasily Gorbik <gor@linux.ibm.com> Signed-off-by:

Heiko Carstens <hca@linux.ibm.com> Signed-off-by:

Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/set_memory.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -2,6 +2,10 @@
		#ifndef _ASMS390_SET_MEMORY_H
		#define _ASMS390_SET_MEMORY_H

		#include <linux/mutex.h>

		extern struct mutex cpa_mutex;

		#define SET_MEMORY_RO 1UL
		#define SET_MEMORY_RW 2UL
		#define SET_MEMORY_NX 4UL

arch/s390/mm/dump_pagetables.c

+3 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		#include <linux/set_memory.h>
		#include <linux/ptdump.h>
		#include <linux/seq_file.h>
		#include <linux/debugfs.h>
		@@ -130,7 +131,9 @@ static int ptdump_show(struct seq_file m, void v)
		};

		get_online_mems();
		mutex_lock(&cpa_mutex);
		ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
		mutex_unlock(&cpa_mutex);
		put_online_mems();
		return 0;
		}

arch/s390/mm/pageattr.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -278,7 +278,7 @@ static int walk_p4d_level(pgd_t *pgd, unsigned long addr, unsigned long end,
		return rc;
		}

		static DEFINE_MUTEX(cpa_mutex);
		DEFINE_MUTEX(cpa_mutex);

		static int change_page_attr(unsigned long addr, unsigned long end,
		unsigned long flags)

Admin message