On 02. 12. 21, 10:59, Jiri Slaby wrote:
On 01. 12. 21, 14:55, Pasha Tatashin wrote:
On Wed, Dec 1, 2021 at 3:44 AM Jiri Slaby <jirislaby@xxxxxxxxxx> wrote:
On 01. 12. 21, 9:00, Jiri Slaby wrote:
On 23. 11. 21, 22:48, Pasha Tatashin wrote:
Add page table check hooks into routines that modify user page tables.
Hi,
I bisected to this as this causes crashes during modules load:
And it's not enough to unset CONFIG_PAGE_TABLE_CHECK_ENFORCED. I had to
unset CONFIG_PAGE_TABLE_CHECK completely to get rid of this.
Hi,
Thanks for reporting this. Seems like module load for some reasons
does not like the static branches. However, I was not able to repro
this. Could you please share your config and the module that you were
loading?
It's the openSUSE's -next config:
https://raw.githubusercontent.com/openSUSE/kernel-source/linux-next/config/x86_64/vanilla
But with CONFIG_IWLMEI=n (as that fails to link).
One has to load i915, other modules (71 on my system) are apparently fine.
i915 tries to patch your `page_table_check_disabled' which is defined as
`DEFINE_STATIC_KEY_TRUE_RO':
> jump_label_add_module: key=__tracepoint_mmap_lock_released
(ffffffff93f36d88) mod=0000000000000000
> jump_label_add_module: key=hugetlb_free_vmemmap_enabled_key
(ffffffff94873560) mod=0000000000000000
> jump_label_add_module: key=devmap_managed_key (ffffffff94902700)
mod=0000000000000000
> jump_label_add_module: key=page_table_check_disabled
(ffffffff939da760) mod=0000000000000000
> BUG: unable to handle page fault for address: ffffffff939da768
Provided you EXPORT page_table_check_disabled and it can be used from
modules, it can be barely marked as RO. So the below indeed fixes the
problem for me:
--- a/mm/page_table_check.c
+++ b/mm/page_table_check.c
@@ -18,7 +18,7 @@ struct page_table_check {
static bool __page_table_check_enabled __initdata =
IS_ENABLED(CONFIG_PAGE_TABLE_CHECK_ENFORCED);
-DEFINE_STATIC_KEY_TRUE_RO(page_table_check_disabled);
+DEFINE_STATIC_KEY_TRUE(page_table_check_disabled);
EXPORT_SYMBOL(page_table_check_disabled);
static int __init early_page_table_check_param(char *buf)
regards,
--
js
suse labs
