From: Jiri Slaby <jirislaby@kernel.org>
To: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Paul Turner <pjt@google.com>,
weixugc@google.com, Greg Thelen <gthelen@google.com>,
Ingo Molnar <mingo@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
Will Deacon <will@kernel.org>, Mike Rapoport <rppt@kernel.org>,
Kees Cook <keescook@chromium.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
masahiroy@kernel.org, Sami Tolvanen <samitolvanen@google.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>,
frederic@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: Re: [PATCH 3/3] x86: mm: add x86_64 support for page table check
Date: Thu, 2 Dec 2021 11:05:47 +0100 [thread overview]
Message-ID: <172f894c-01ab-cd9f-3292-1ba811f7222a@kernel.org> (raw)
In-Reply-To: <a0968570-a25a-a7e3-3ee5-b7275286c9d1@kernel.org>
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@kernel.org> 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
next prev parent reply other threads:[~2021-12-02 10:06 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 21:48 [PATCH 0/3] page table check Pasha Tatashin
2021-11-23 21:48 ` [PATCH 1/3] mm: ptep_clear() page table helper Pasha Tatashin
2021-11-23 21:48 ` [PATCH 2/3] mm: page table check Pasha Tatashin
2021-11-27 8:10 ` Fusion Future
2021-11-27 8:14 ` Fushan Wen
2021-11-27 8:41 ` Fusion Future
2021-11-27 19:48 ` Pasha Tatashin
2021-11-28 8:13 ` Fusion Future
2021-11-28 9:37 ` Fusion
2021-11-28 16:54 ` Fusion Future
2021-11-28 16:57 ` Pasha Tatashin
2021-11-29 2:55 ` Fusion Future
2021-11-30 19:25 ` Pasha Tatashin
2021-12-01 8:38 ` Jiri Slaby
2021-11-23 21:48 ` [PATCH 3/3] x86: mm: add x86_64 support for " Pasha Tatashin
2021-12-01 8:00 ` Jiri Slaby
2021-12-01 8:44 ` Jiri Slaby
2021-12-01 13:55 ` Pasha Tatashin
2021-12-02 9:59 ` Jiri Slaby
2021-12-02 10:05 ` Jiri Slaby [this message]
2021-12-02 10:30 ` Muchun Song
2021-12-02 15:01 ` Pasha Tatashin
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