Re: [mm] c4344e8035: WARNING: CPU: 0 PID: 101 at mm/memory.c:303 __tlb_remove_page_size+0x25/0x99

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 10/12, Aneesh Kumar K.V wrote:
>kernel test robot <xiaolong.ye@intel.com> writes:
>
>> FYI, we noticed the following commit:
>>
>> https://github.com/0day-ci/linux Aneesh-Kumar-K-V/mm-Use-the-correct-page-size-when-removing-the-page/20161012-013446
>> commit c4344e80359420d7574b3b90fddf53311f1d24e6 ("mm: Remove the page size change check in tlb_remove_page")
>>
>> in testcase: boot
>>
>> on test machine: qemu-system-i386 -enable-kvm -cpu Haswell,+smep,+smap -m 360M
>>
>> caused below changes:
>>
>>
>> +------------------------------------------------+------------+------------+
>> |                                                | eff764128d | c4344e8035 |
>> +------------------------------------------------+------------+------------+
>> | boot_successes                                 | 59         | 0          |
>> | boot_failures                                  | 0          | 43         |
>> | WARNING:at_mm/memory.c:#__tlb_remove_page_size | 0          | 43         |
>> | calltrace:SyS_execve                           | 0          | 43         |
>> | calltrace:run_init_process                     | 0          | 21         |
>> +------------------------------------------------+------------+------------+
>>
>>
>>
>> [    4.096204] Write protecting the kernel text: 3148k
>> [    4.096911] Write protecting the kernel read-only data: 1444k
>> [    4.120357] ------------[ cut here ]------------
>> [    4.121078] WARNING: CPU: 0 PID: 101 at mm/memory.c:303 __tlb_remove_page_size+0x25/0x99
>> [    4.122380] Modules linked in:
>> [    4.122788] CPU: 0 PID: 101 Comm: run-parts Not tainted 4.8.0-mm1-00315-gc4344e8 #5
>> [    4.123956]  bd145dc4 b111e5e6 bd145de0 b10320dc 0000012f b10974d1 bd145e70 c4954170
>> [    4.125277]  c4954170 bd145df4 b103215f 00000009 00000000 00000000 bd145e04 b10974d1
>> [    4.126424]  c4954170 bd145e70 bd145e14 b10263ca bd145e70 bd47bafc bd145e40 b109767a
>> [    4.127622] Call Trace:
>
>Thanks for the report. The below change should fix this.
>
>commit 18c929e7cf672da617dc218c6265366bf78b1644
>Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>Date:   Wed Oct 12 08:40:41 2016 +0530
>
>    update mmu gather page size before flushing page table cache
>
>diff --git a/mm/memory.c b/mm/memory.c
>index 26d1ba8c87e6..7e7eccb82a2b 100644
>--- a/mm/memory.c
>+++ b/mm/memory.c
>@@ -526,7 +526,11 @@ void free_pgd_range(struct mmu_gather *tlb,
> 		end -= PMD_SIZE;
> 	if (addr > end - 1)
> 		return;
>-
>+	/*
>+	 * We add page table cache pages with PAGE_SIZE,
>+	 * (see pte_free_tlb()), flush the tlb if we need
>+	 */
>+	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
> 	pgd = pgd_offset(tlb->mm, addr);
> 	do {
> 		next = pgd_addr_end(addr, end);
>

Just applied this fix on top of commit c4344e8035 and confirmed that
reportedwarning is gone with this fix.

Tested-by: Xiaolong Ye <xiaolong.ye@intel.com>

=========================================================================================
compiler/kconfig/rootfs/sleep/tbox_group/testcase:
  gcc-6/i386-randconfig-s1-201641/quantal-core-i386.cgz/1/vm-vp-quantal-i386/boot

commit:
  c4344e80359420d7574b3b90fddf53311f1d24e6
  384db818365c90b91d8bad80be188765e801cf58 ("update mmu gather page size before flushing page table cache")

c4344e80359420d7 384db818365c90b91d8bad80be
---------------- --------------------------
       fail:runs  %reproduction    fail:runs
           |             |             |
         24:24        -100%            :5     dmesg.WARNING:at_mm/memory.c:#__tlb_remove_page_size

Thanks,
Xiaolong