Messages in this thread | | | Date | Thu, 20 Jan 2022 15:54:14 +0000 | From | Matthew Wilcox <> | Subject | Re: [PATCH v4 64/66] nommu: Remove uses of VMA linked list |
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On Thu, Jan 20, 2022 at 04:06:21PM +0100, Vlastimil Babka wrote: > On 12/1/21 15:30, Liam Howlett wrote: > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > > > Use the maple tree or VMA iterator instead. This is faster and will > > allow us to shrink the VMA. > > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > > Acked-by: Vlastimil Babka <vbabka@suse.cz> > > But I think some fixup needed: > > > @@ -1456,12 +1458,14 @@ void exit_mmap(struct mm_struct *mm) > > > > mm->total_vm = 0; > > > > - while ((vma = mm->mmap)) { > > - mm->mmap = vma->vm_next; > > + mmap_write_lock(mm); > > If locking was missing, should have been added sooner than now?
I don't think so? This is the exit_mmap() path, so we know nobody has access to the mm. We didn't need to hold the lock at this point before, but now for_each_vma() will check we're holding the mmap_lock.
> > + for_each_vma(vmi, vma) { > > delete_vma_from_mm(vma); > > delete_vma(mm, vma); > > cond_resched(); > > } > > + __mt_destroy(&mm->mm_mt); > > And this at the point mm_mt was added?
You mean we should have been calling __mt_destroy() earlier in the patch series? Umm ... I'll defer to Liam on that one.
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