Nathan Chancellor <nat...@kernel.org> writes:
> Hi Aneesh,
>
> On Thu, Apr 22, 2021 at 11:13:17AM +0530, Aneesh Kumar K.V wrote:
>> pmd/pud_populate is the right interface to be used to set the respective
>> page table entries. Some architectures like ppc64 do assume that
>> set_pmd/pud_at
>> can only be used to set a hugepage PTE. Since we are not setting up a
>> hugepage
>> PTE here, use the pmd/pud_populate interface.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
>> ---
>> mm/mremap.c | 7 +++----
>> 1 file changed, 3 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/mremap.c b/mm/mremap.c
>> index ec8f840399ed..574287f9bb39 100644
>> --- a/mm/mremap.c
>> +++ b/mm/mremap.c
>> @@ -26,6 +26,7 @@
>>
>> #include <asm/cacheflush.h>
>> #include <asm/tlbflush.h>
>> +#include <asm/pgalloc.h>
>>
>> #include "internal.h"
>>
>> @@ -257,9 +258,8 @@ static bool move_normal_pmd(struct vm_area_struct *vma,
>> unsigned long old_addr,
>> pmd_clear(old_pmd);
>>
>> VM_BUG_ON(!pmd_none(*new_pmd));
>> + pmd_populate(mm, new_pmd, (pgtable_t)pmd_page_vaddr(pmd));
>>
>> - /* Set the new pmd */
>> - set_pmd_at(mm, new_addr, new_pmd, pmd);
>> flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
>> if (new_ptl != old_ptl)
>> spin_unlock(new_ptl);
>> @@ -306,8 +306,7 @@ static bool move_normal_pud(struct vm_area_struct *vma,
>> unsigned long old_addr,
>>
>> VM_BUG_ON(!pud_none(*new_pud));
>>
>> - /* Set the new pud */
>> - set_pud_at(mm, new_addr, new_pud, pud);
>> + pud_populate(mm, new_pud, (pmd_t *)pud_page_vaddr(pud));
>> flush_tlb_range(vma, old_addr, old_addr + PUD_SIZE);
>> if (new_ptl != old_ptl)
>> spin_unlock(new_ptl);
>> --
>> 2.30.2
>>
>>
>
> This commit causes my WSL2 VM to close when compiling something memory
> intensive, such as an x86_64_defconfig + CONFIG_LTO_CLANG_FULL=y kernel
> or LLVM/Clang. Unfortunately, I do not have much further information to
> provide since I do not see any sort of splat in dmesg right before it
> closes and I have found zero information about getting the previous
> kernel message in WSL2 (custom init so no systemd or anything).
>
> The config file is the stock one from Microsoft:
>
> https://github.com/microsoft/WSL2-Linux-Kernel/blob/a571dc8cedc8e0e56487c0dc93243e0b5db8960a/Microsoft/config-wsl
>
> I have attached my .config anyways, which includes CONFIG_DEBUG_VM,
> which does not appear to show anything out of the ordinary. I have also
> attached a dmesg just in case anything sticks out. I am happy to provide
> any additional information or perform additional debugging steps as
> needed.
>
Can you try this change?
modified mm/mremap.c
@@ -279,7 +279,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma,
unsigned long old_addr,
pmd_clear(old_pmd);
VM_BUG_ON(!pmd_none(*new_pmd));
- pmd_populate(mm, new_pmd, (pgtable_t)pmd_page_vaddr(pmd));
+ pmd_populate(mm, new_pmd, pmd_pgtable(pmd));
if (new_ptl != old_ptl)
spin_unlock(new_ptl);
