From da1694ad9e8d13484c8b4ecaabde0bd7b958442a Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 7 Sep 2020 17:20:05 +0200 Subject: s390/mm,ptdump: hold cpa mutex while walking for kernel page table dump This is currently only preventing that outdated information is provided to user space.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 Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/mm/dump_pagetables.c | 3 +++ arch/s390/mm/pageattr.c | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-) (limited to 'arch/s390/mm') diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c index 3c5e4055a3d2..09c7179cb17d 100644 --- a/arch/s390/mm/dump_pagetables.c +++ b/arch/s390/mm/dump_pagetables.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include @@ -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; } diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index c5c52ec2b46f..ed8e5b3575d5 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -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) -- cgit v1.2.3