Re: [PATCH v3 1/3] hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)
On Fri, Apr 05, 2013 at 02:32:08PM -0400, KOSAKI Motohiro wrote:
> (4/3/13 2:35 PM), 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.
>
> I don't think this is enough explanations. Let's explain the code meaning
> time to time order.
>
> First, we had no madvice(DONTDUMP) nor coredump_filter(HUGETLB). then hugetlb
> pages were never dumped.
>
> Second, I added coredump_filter(HUGETLB). and then vm_dump_size became..
>
> vm_dump_size()
> {
> /* Hugetlb memory check */
> if (vma->vm_flags & VM_HUGETLB) {
> ..
> goto whole;
> }
> if (vma->vm_flags & VM_RESERVED)
> return 0;
>
> The point is, hugetlb was checked before VM_RESERVED. i.e. hugetlb core dump
> ignored
> VM_RESERVED. At this time, "if (vma->vm_flags & VM_HUGETLB)" statement don't
> need
> return 0 because VM_RESERVED prevented to go into the subsequent flag checks.
>
> Third, Jason added madvise(DONTDUMP). then vm_dump_size became...
>
> vm_dump_size()
> {
>if (vma->vm_flags & VM_NODUMP)
>return 0;
>
> /* Hugetlb memory check */
> if (vma->vm_flags & VM_HUGETLB) {
> ..
> goto whole;
> }
> if (vma->vm_flags & VM_RESERVED)
> return 0;
>
> Look, VM_NODUMP and VM_RESERVED had similar and different meanings at this
> time.
>
> Finally, Konstantin removed VM_RESERVED and hugetlb coredump behavior
> has been changed.
Things were/are quite complicated, and this is a wonderful step-by-step
explanation.
Thank you very much.
Naoya
> Thus, patch [1/3] and [2/3] should be marked [stable for v3.6 or later].
>
> Anyway, this patch is correct. Thank you!
>
> Acked-by: KOSAKI Motohiro
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Re: [PATCH v3 1/3] hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)
(4/3/13 2:35 PM), 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.
I don't think this is enough explanations. Let's explain the code meaning
time to time order.
First, we had no madvice(DONTDUMP) nor coredump_filter(HUGETLB). then hugetlb
pages were never dumped.
Second, I added coredump_filter(HUGETLB). and then vm_dump_size became..
vm_dump_size()
{
/* Hugetlb memory check */
if (vma->vm_flags & VM_HUGETLB) {
..
goto whole;
}
if (vma->vm_flags & VM_RESERVED)
return 0;
The point is, hugetlb was checked before VM_RESERVED. i.e. hugetlb core dump
ignored
VM_RESERVED. At this time, "if (vma->vm_flags & VM_HUGETLB)" statement don't
need
return 0 because VM_RESERVED prevented to go into the subsequent flag checks.
Third, Jason added madvise(DONTDUMP). then vm_dump_size became...
vm_dump_size()
{
if (vma->vm_flags & VM_NODUMP)
return 0;
/* Hugetlb memory check */
if (vma->vm_flags & VM_HUGETLB) {
..
goto whole;
}
if (vma->vm_flags & VM_RESERVED)
return 0;
Look, VM_NODUMP and VM_RESERVED had similar and different meanings at this time.
Finally, Konstantin removed VM_RESERVED and hugetlb coredump behavior
has been changed.
Thus, patch [1/3] and [2/3] should be marked [stable for v3.6 or later].
Anyway, this patch is correct. Thank you!
Acked-by: KOSAKI Motohiro
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v3 1/3] hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)
On 04/03/2013 02:35 PM, 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. ChangeLog v3: - move 'return 0' into a separate patch ChangeLog v2: - add 'return 0' in hugepage memory check Signed-off-by: Naoya Horiguchi Acked-by: Konstantin Khlebnikov Acked-by: Michal Hocko Cc: sta...@vger.kernel.org Reviewed-by: Rik van Riel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v3 1/3] hugetlbfs: stop setting VM_DONTDUMP in initializing vma(VM_HUGETLB)
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. ChangeLog v3: - move 'return 0' into a separate patch ChangeLog v2: - add 'return 0' in hugepage memory check Signed-off-by: Naoya Horiguchi Acked-by: Konstantin Khlebnikov Acked-by: Michal Hocko Cc: sta...@vger.kernel.org --- fs/hugetlbfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git v3.9-rc3.orig/fs/hugetlbfs/inode.c v3.9-rc3/fs/hugetlbfs/inode.c index 84e3d85..523464e 100644 --- v3.9-rc3.orig/fs/hugetlbfs/inode.c +++ v3.9-rc3/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_DONTEXPAND | VM_DONTDUMP; + vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND; vma->vm_ops = &hugetlb_vm_ops; if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT)) -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
