On Tue, Feb 22, 2022 at 06:54:38PM +0000, Liam Howlett wrote: > * Catalin Marinas <catalin.marinas@xxxxxxx> [220222 12:26]: > > On Tue, Feb 22, 2022 at 04:20:16PM +0000, Will Deacon wrote: > > > On Tue, Feb 22, 2022 at 02:26:03PM +0000, Liam Howlett wrote: > > > > The vma iterator uses the maple tree, so this patch would resolve the > > > > conflict but both branches are needed. > > > > > > I'm not really sure what to do here, then. I think the conflict is nasty > > > enough that we should resolve it before the trees reach Linus, but there > > > doesn't seem to be a way forward other than one of us merging the other > > > branch. I'd like to avoid having MTE coredump support depend on the maple > > > tree work. > > > > > > Is there some way you could provide a branch which implements > > > for_each_vma() using the old vma list, and then the maple tree series > > > could switch that over to the maple tree without breaking things? > > > > Without a branch, we could apply something like below on top of Liam's > > patch and revert it once the maple tree is upstream: > > > > diff --git a/arch/arm64/kernel/elfcore.c b/arch/arm64/kernel/elfcore.c > > index 930a0bc4cac4..400ec7a902df 100644 > > --- a/arch/arm64/kernel/elfcore.c > > +++ b/arch/arm64/kernel/elfcore.c > > @@ -8,6 +8,13 @@ > > #include <asm/cpufeature.h> > > #include <asm/mte.h> > > > > +#ifndef VMA_ITERATOR > > +#define VMA_ITERATOR(name, mm, addr) \ > > + struct mm_struct *name = mm > > +#define for_each_vma(vmi, vma) \ > > + for (vma = vmi->mmap; vma; vma = vma->vm_next) > > +#endif > > + > > #define for_each_mte_vma(vmi, vma) \ > > if (system_supports_mte()) \ > > for_each_vma(vmi, vma) \ > > Note that the current VMA_ITERATOR takes a new type and not the mm. Well, in you proposed fix, it does take current->mm. > Since I am removing the linked list (mm->mmap and vma->vm_next), then > the build will fail if this patch and the maple tree branch exist > together. The iterator may also not start at the start of the list (but > usually does) and may not run through the entire list; see > vma_for_each_range() in the patch set. My hack above is only temporary to allow building the arm64 tree on its own (no maple tree branch) and with your patch on top. In -next, when merged with the maple tree branch, the VMA_ITERATOR macro is already defined and the above hack skipped. We'll revert this hack around -rc1. Note that the hack above is only in the arm64 elfcore.c, not a generic API solution. -- Catalin
