Re: [PATCH v9 02/10] mm: Non-pmd-mappable, large folios for folio_add_new_anon_rmap()

Ryan Roberts
2024-01-24T12:02:59Z

On 24/01/2024 11:19, Jiri Olsa wrote:
> On Wed, Jan 24, 2024 at 12:15:52PM +0100, Sven Schnelle wrote:
>> Ryan Roberts <ryan.roberts@arm.com> writes:
>>
>>> On 14/01/2024 20:55, Jiri Olsa wrote:
>>>> On Sun, Jan 14, 2024 at 06:33:56PM +0100, David Hildenbrand wrote:
>>>>> On 13.01.24 23:42, Jiri Olsa wrote:
>>>>>> On Thu, Dec 07, 2023 at 04:12:03PM +0000, Ryan Roberts wrote:
>>>>>>> In preparation for supporting anonymous multi-size THP, improve
>>>>>>> folio_add_new_anon_rmap() to allow a non-pmd-mappable, large folio to be
>>>>>>> passed to it. In this case, all contained pages are accounted using the
>>>>>>> order-0 folio (or base page) scheme.
>>>>>>>
>>>>>>> Reviewed-by: Yu Zhao <yuzhao@google.com>
>>>>>>> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
>>>>>>> Reviewed-by: David Hildenbrand <david@redhat.com>
>>>>>>> Reviewed-by: Barry Song <v-songbaohua@oppo.com>
>>>>>>> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>>>>>>> Tested-by: John Hubbard <jhubbard@nvidia.com>
>>>>>>> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
>>>>>>> ---
>>>>>>> mm/rmap.c | 28 ++++++++++++++++++++--------
>>>>>>> 1 file changed, 20 insertions(+), 8 deletions(-)
>>>>>>>
>>>>>>> diff --git a/mm/rmap.c b/mm/rmap.c
>>>>>>> index 2a1e45e6419f..846fc79f3ca9 100644
>>>>>>> --- a/mm/rmap.c
>>>>>>> +++ b/mm/rmap.c
>>>>>>> @@ -1335,32 +1335,44 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
>>>>>>> * This means the inc-and-test can be bypassed.
>>>>>>> * The folio does not have to be locked.
>>>>>>> *
>>>>>>> - * If the folio is large, it is accounted as a THP. As the folio
>>>>>>> + * If the folio is pmd-mappable, it is accounted as a THP. As the folio
>>>>>>> * is new, it's assumed to be mapped exclusively by a single process.
>>>>>>> */
>>>>>>> void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
>>>>>>> unsigned long address)
>>>>>>> {
>>>>>>> - int nr;
>>>>>>> + int nr = folio_nr_pages(folio);
>>>>>>> - VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
>>>>>>> + VM_BUG_ON_VMA(address < vma->vm_start ||
>>>>>>> + address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
>>>>>>
>>>>>> hi,
>>>>>> I'm hitting this bug (console output below) with adding uprobe
>>>>>> on simple program like:
>>>>>>
>>>>>> $ cat up.c
>>>>>> int main(void)
>>>>>> {
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> # bpftrace -e 'uprobe:/home/jolsa/up:_start {}'
>>>>>>
>>>>>> $ ./up
>>>>>>
>>>>>> it's on top of current linus tree master:
>>>>>> 052d534373b7 Merge tag 'exfat-for-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat
>>>>>>
>>>>>> before this patch it seems to work, I can send my .config if needed
>>>
>>> Thanks for the bug report!
>>
>> I just hit the same bug in our CI, but can't find the fix in -next. Is
>> this in the queue somewhere?
>
> we hit it as well, but I can see the fix in linux-next/master
>
> 4c137bc28064 uprobes: use pagesize-aligned virtual address when replacing pages

Yes that's the one. Just to confirm: you are still hitting the VM_BUG_ON despite
having this change in your kernel? Could you please send over the full bug log?

>
> jirka