On Thu, Dec 2, 2021 at 6:06 PM Jiri Slaby <jirislaby@xxxxxxxxxx> wrote: > > 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: Agree. I had encountered a similar problem some months ago. In one word, DEFINE_STATIC_KEY_TRUE_RO() and EXPORT_SYMBOL() are mutually exclusive. Thanks. > > --- 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
