On 5/17/21 9:03 PM, Anshuman Khandual wrote:
>
>
> On 5/14/21 2:57 AM, Matthew Wilcox wrote:
>> On Thu, May 13, 2021 at 10:29:49AM -0700, Randy Dunlap wrote:
>>> On 5/12/21 10:44 PM, Stephen Rothwell wrote:
>>>> Hi all,
>>>>
>>>> Changes since 20210512:
>>>>
>>>
>>> on x86_64:
>>>
>>> In function ‘__mm_zero_struct_page.isra.75’,
>>> inlined from ‘__init_single_page.isra.76’ at ../mm/page_alloc.c:1494:2:
>>> ./../include/linux/compiler_types.h:328:38: error: call to ‘__compiletime_assert_162’ declared with attribute error: BUILD_BUG_ON failed: sizeof(struct page) > 80
>>
>> Hmm.
>>
>> struct {
>> long unsigned int _pt_pad_1; /* 8 8 */
>> pgtable_t pmd_huge_pte; /* 16 8 */
>> long unsigned int _pt_pad_2; /* 24 8 */
>> union {
>> struct mm_struct * pt_mm; /* 32 8 */
>> atomic_t pt_frag_refcount; /* 32 4 */
>> }; /* 32 8 */
>> spinlock_t ptl; /* 40 72 */
>> }; /* 8 104 */
>>
>> #if ALLOC_SPLIT_PTLOCKS
>> spinlock_t *ptl;
>> #else
>> spinlock_t ptl;
>> #endif
>>
>> something has disabled ALLOC_SPLIT_PTLOCKS when it ought to be enabled.
>>
>> #if USE_SPLIT_PTE_PTLOCKS
>> #define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8)
>> #else
>> #define ALLOC_SPLIT_PTLOCKS 0
>> #endif
>>
>> Oh. This is Anshuman's fault.
>>
>> commit 9b8a39056e2472592a5e5897987387f43038b8ba
>> Author: Anshuman Khandual <anshuman.khandual@xxxxxxx>
>> Date: Tue May 11 15:06:01 2021 +1000
>>
>> mm/thp: make ALLOC_SPLIT_PTLOCKS dependent on USE_SPLIT_PTE_PTLOCKS
>>
>>
>
> Previously ALLOC_SPLIT_PTLOCKS was evaluated and the spin lock element
> in struct page was getting created independent of whether split pte
> locks are being used or not. AFAICS without USE_SPLIT_PTE_PTLOCKS, it
> does not really matter whether struct page has spinlock_t *ptl or ptl
> element because that is not going to be used. Should the BUILD_BUG_ON()
> evaluation be changed when USE_SPLIT_PTE_PTLOCKS is not enabled or we
> could something like this which drops the ptl element in such cases ?
>
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -152,11 +152,13 @@ struct page {
> struct mm_struct *pt_mm; /* x86 pgds only */
> atomic_t pt_frag_refcount; /* powerpc */
> };
> +#if USE_SPLIT_PTE_PTLOCKS
> #if ALLOC_SPLIT_PTLOCKS
> spinlock_t *ptl;
> #else
> spinlock_t ptl;
> #endif
> +#endif
> };
> struct { /* ZONE_DEVICE pages */
> /** @pgmap: Points to the hosting device page map. */
>
OK, that works. Thanks.
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> # build-tested
I guess you should send a proper patch to Andrew. The code above
is whitespace-damaged (cut'n'paste).
--
~Randy
