Re: linux-next: build failure after merge of the maple tree

[Liam Howlett <liam.howlett@oracle.com>]

* Will Deacon <will@kernel.org> [220217 14:24]:
> On Thu, Feb 17, 2022 at 07:18:57PM +1100, Stephen Rothwell wrote:
> > Hi all,
> > 
> > After merging the maple tree, today's linux-next build (arm64 defconfig)
> > failed like this:
> > 
> > arch/arm64/kernel/elfcore.c: In function 'elf_core_extra_phdrs':
> > arch/arm64/kernel/elfcore.c:13:35: error: 'struct mm_struct' has no member named 'mmap'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                   ^~
> > arch/arm64/kernel/elfcore.c:69:9: note: in expansion of macro 'for_each_mte_vma'
> >    69 |         for_each_mte_vma(current, vma)
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c:13:57: error: 'struct vm_area_struct' has no member named 'vm_next'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                                         ^~
> > arch/arm64/kernel/elfcore.c:69:9: note: in expansion of macro 'for_each_mte_vma'
> >    69 |         for_each_mte_vma(current, vma)
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c: In function 'elf_core_write_extra_phdrs':
> > arch/arm64/kernel/elfcore.c:13:35: error: 'struct mm_struct' has no member named 'mmap'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                   ^~
> > arch/arm64/kernel/elfcore.c:79:9: note: in expansion of macro 'for_each_mte_vma'
> >    79 |         for_each_mte_vma(current, vma) {
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c:13:57: error: 'struct vm_area_struct' has no member named 'vm_next'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                                         ^~
> > arch/arm64/kernel/elfcore.c:79:9: note: in expansion of macro 'for_each_mte_vma'
> >    79 |         for_each_mte_vma(current, vma) {
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c: In function 'elf_core_extra_data_size':
> > arch/arm64/kernel/elfcore.c:13:35: error: 'struct mm_struct' has no member named 'mmap'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                   ^~
> > arch/arm64/kernel/elfcore.c:104:9: note: in expansion of macro 'for_each_mte_vma'
> >   104 |         for_each_mte_vma(current, vma)
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c:13:57: error: 'struct vm_area_struct' has no member named 'vm_next'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                                         ^~
> > arch/arm64/kernel/elfcore.c:104:9: note: in expansion of macro 'for_each_mte_vma'
> >   104 |         for_each_mte_vma(current, vma)
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c: In function 'elf_core_write_extra_data':
> > arch/arm64/kernel/elfcore.c:13:35: error: 'struct mm_struct' has no member named 'mmap'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                   ^~
> > arch/arm64/kernel/elfcore.c:114:9: note: in expansion of macro 'for_each_mte_vma'
> >   114 |         for_each_mte_vma(current, vma) {
> >       |         ^~~~~~~~~~~~~~~~
> > arch/arm64/kernel/elfcore.c:13:57: error: 'struct vm_area_struct' has no member named 'vm_next'
> >    13 |                 for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)      \
> >       |                                                         ^~
> > arch/arm64/kernel/elfcore.c:114:9: note: in expansion of macro 'for_each_mte_vma'
> >   114 |         for_each_mte_vma(current, vma) {
> >       |         ^~~~~~~~~~~~~~~~
> > 
> > Caused by commit
> > 
> >   b09e8361a4c3 ("mm: Remove the vma linked list")
> > 
> > interacting with commit
> > 
> >   6dd8b1a0b6cb ("arm64: mte: Dump the MTE tags in the core file")
> > 
> > from the arm64 tree.
> 
> Yikes, this is quite a mess. Liam -- how would you like to resolve this?

The removal of the vma linked list means tsk->mm->mmap and vma->vm_next
are no longer usable.  for_each_mte_vma() could be altered to take a vma
iterator:

#define for_each_mte_vma(vmi, vma)					\
	if (system_supports_mte())					\
		for_each_vma(vmi, vma)					\
			if (vma->vm_flags & VM_MTE)


Then used as such:
 VMA_ITERATOR(vmi, tsk->mm, 0);
...

for_each_mte_vma(vmi, vma) {
...
}

Where might I find a branch containing this patch?  Is it a stand alone
or part of a larger series?

Liam