Konstantin Khlebnikov wrote:
> Naoya Horiguchi wrote:
>> On Thu, Mar 28, 2013 at 09:03:16PM +0400, Konstantin Khlebnikov wrote:
>>> Naoya Horiguchi wrote:
>>>> Currently we fail to include any data on hugepages into coredump,
>>>> because VM_DONTDUMP is set on hugetlbfs's vma. This behavior was recently
>>>> introduced by commit 314e51b98 "mm: kill vma flag VM_RESERVED and
>>>> mm->reserved_vm counter". This looks to me a serious regression,
>>>> so let's fix it.
>>>
>>> That was introduced in my patch? Really?
>>> Here was VM_RESERVED and it had the same effect as VM_DONTDUMP. At least I
>>> thought so.
>>
>> vma_dump_size() does like this (the diff is the one in 314e51b98):
>>
>> static unsigned long vma_dump_size(struct vm_area_struct *vma,
>> unsigned long mm_flags)
>> {
>> #define FILTER(type) (mm_flags& (1UL<< MMF_DUMP_##type))
>>
>> /* always dump the vdso and vsyscall sections */
>> if (always_dump_vma(vma))
>> goto whole;
>>
>> if (vma->vm_flags& VM_DONTDUMP)
>> return 0;
>>
>> /* Hugetlb memory check */
>> if (vma->vm_flags& VM_HUGETLB) {
>> if ((vma->vm_flags& VM_SHARED)&&
>> FILTER(HUGETLB_SHARED))
>> goto whole;
>> if (!(vma->vm_flags& VM_SHARED)&&
>> FILTER(HUGETLB_PRIVATE))
>> goto whole;
>> }
>>
>> /* Do not dump I/O mapped devices or special mappings */
>> - if (vma->vm_flags& (VM_IO | VM_RESERVED))
>> + if (vma->vm_flags& VM_IO)
>> return 0;
>>
>> We have hugetlb memory check after VM_DONTDUMP check, so the following
>> changed the behavior.
>
> Ok, I missed this in my patch.
>
>>
>> --- a/fs/hugetlbfs/inode.c
>> +++ b/fs/hugetlbfs/inode.c
>> @@ -110,7 +110,7 @@ static int hugetlbfs_file_mmap(struct file *file,
>> struct vm_area_struct *vma)
>> * way when do_mmap_pgoff unwinds (may be important on powerpc
>> * and ia64).
>> */
>> - vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
>> + vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND | VM_DONTDUMP;
>> vma->vm_ops =&hugetlb_vm_ops;
>>
>> if (vma->vm_pgoff& (~huge_page_mask(h)>> PAGE_SHIFT))
>>
>> I think we don't have to set VM_DONTDUMP on hugetlbfs's vma.
>
> Acked-by: Konstantin Khlebnikov<khlebni...@openvz.org>
hugetlb coredump filter also should be fixed in this way:
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1154,6 +1154,7 @@ static unsigned long vma_dump_size(struct vm_area_struct
*vma,
goto whole;
if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE))
goto whole;
+ return 0;
}
/* Do not dump I/O mapped devices or special mappings */
>
>>
>> Thanks,
>> Naoya
>
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