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

Sven Schnelle
2024-01-24T11:16:41Z

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?

Thanks
Sven